*> \brief \b DBBCSD
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DBBCSD + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dbbcsd.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dbbcsd.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dbbcsd.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DBBCSD( JOBU1, JOBU2, JOBV1T, JOBV2T, TRANS, M, P, Q,
*                          THETA, PHI, U1, LDU1, U2, LDU2, V1T, LDV1T,
*                          V2T, LDV2T, B11D, B11E, B12D, B12E, B21D, B21E,
*                          B22D, B22E, WORK, LWORK, INFO )
*
*       .. Scalar Arguments ..
*       CHARACTER          JOBU1, JOBU2, JOBV1T, JOBV2T, TRANS
*       INTEGER            INFO, LDU1, LDU2, LDV1T, LDV2T, LWORK, M, P, Q
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   B11D( * ), B11E( * ), B12D( * ), B12E( * ),
*      $                   B21D( * ), B21E( * ), B22D( * ), B22E( * ),
*      $                   PHI( * ), THETA( * ), WORK( * )
*       DOUBLE PRECISION   U1( LDU1, * ), U2( LDU2, * ), V1T( LDV1T, * ),
*      $                   V2T( LDV2T, * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DBBCSD computes the CS decomposition of an orthogonal matrix in
*> bidiagonal-block form,
*>
*>
*>     [ B11 | B12 0  0 ]
*>     [  0  |  0 -I  0 ]
*> X = [----------------]
*>     [ B21 | B22 0  0 ]
*>     [  0  |  0  0  I ]
*>
*>                               [  C | -S  0  0 ]
*>                   [ U1 |    ] [  0 |  0 -I  0 ] [ V1 |    ]**T
*>                 = [---------] [---------------] [---------]   .
*>                   [    | U2 ] [  S |  C  0  0 ] [    | V2 ]
*>                               [  0 |  0  0  I ]
*>
*> X is M-by-M, its top-left block is P-by-Q, and Q must be no larger
*> than P, M-P, or M-Q. (If Q is not the smallest index, then X must be
*> transposed and/or permuted. This can be done in constant time using
*> the TRANS and SIGNS options. See DORCSD for details.)
*>
*> The bidiagonal matrices B11, B12, B21, and B22 are represented
*> implicitly by angles THETA(1:Q) and PHI(1:Q-1).
*>
*> The orthogonal matrices U1, U2, V1T, and V2T are input/output.
*> The input matrices are pre- or post-multiplied by the appropriate
*> singular vector matrices.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] JOBU1
*> \verbatim
*>          JOBU1 is CHARACTER
*>          = 'Y':      U1 is updated;
*>          otherwise:  U1 is not updated.
*> \endverbatim
*>
*> \param[in] JOBU2
*> \verbatim
*>          JOBU2 is CHARACTER
*>          = 'Y':      U2 is updated;
*>          otherwise:  U2 is not updated.
*> \endverbatim
*>
*> \param[in] JOBV1T
*> \verbatim
*>          JOBV1T is CHARACTER
*>          = 'Y':      V1T is updated;
*>          otherwise:  V1T is not updated.
*> \endverbatim
*>
*> \param[in] JOBV2T
*> \verbatim
*>          JOBV2T is CHARACTER
*>          = 'Y':      V2T is updated;
*>          otherwise:  V2T is not updated.
*> \endverbatim
*>
*> \param[in] TRANS
*> \verbatim
*>          TRANS is CHARACTER
*>          = 'T':      X, U1, U2, V1T, and V2T are stored in row-major
*>                      order;
*>          otherwise:  X, U1, U2, V1T, and V2T are stored in column-
*>                      major order.
*> \endverbatim
*>
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows and columns in X, the orthogonal matrix in
*>          bidiagonal-block form.
*> \endverbatim
*>
*> \param[in] P
*> \verbatim
*>          P is INTEGER
*>          The number of rows in the top-left block of X. 0 <= P <= M.
*> \endverbatim
*>
*> \param[in] Q
*> \verbatim
*>          Q is INTEGER
*>          The number of columns in the top-left block of X.
*>          0 <= Q <= MIN(P,M-P,M-Q).
*> \endverbatim
*>
*> \param[in,out] THETA
*> \verbatim
*>          THETA is DOUBLE PRECISION array, dimension (Q)
*>          On entry, the angles THETA(1),...,THETA(Q) that, along with
*>          PHI(1), ...,PHI(Q-1), define the matrix in bidiagonal-block
*>          form. On exit, the angles whose cosines and sines define the
*>          diagonal blocks in the CS decomposition.
*> \endverbatim
*>
*> \param[in,out] PHI
*> \verbatim
*>          PHI is DOUBLE PRECISION array, dimension (Q-1)
*>          The angles PHI(1),...,PHI(Q-1) that, along with THETA(1),...,
*>          THETA(Q), define the matrix in bidiagonal-block form.
*> \endverbatim
*>
*> \param[in,out] U1
*> \verbatim
*>          U1 is DOUBLE PRECISION array, dimension (LDU1,P)
*>          On entry, a P-by-P matrix. On exit, U1 is postmultiplied
*>          by the left singular vector matrix common to [ B11 ; 0 ] and
*>          [ B12 0 0 ; 0 -I 0 0 ].
*> \endverbatim
*>
*> \param[in] LDU1
*> \verbatim
*>          LDU1 is INTEGER
*>          The leading dimension of the array U1, LDU1 >= MAX(1,P).
*> \endverbatim
*>
*> \param[in,out] U2
*> \verbatim
*>          U2 is DOUBLE PRECISION array, dimension (LDU2,M-P)
*>          On entry, an (M-P)-by-(M-P) matrix. On exit, U2 is
*>          postmultiplied by the left singular vector matrix common to
*>          [ B21 ; 0 ] and [ B22 0 0 ; 0 0 I ].
*> \endverbatim
*>
*> \param[in] LDU2
*> \verbatim
*>          LDU2 is INTEGER
*>          The leading dimension of the array U2, LDU2 >= MAX(1,M-P).
*> \endverbatim
*>
*> \param[in,out] V1T
*> \verbatim
*>          V1T is DOUBLE PRECISION array, dimension (LDV1T,Q)
*>          On entry, a Q-by-Q matrix. On exit, V1T is premultiplied
*>          by the transpose of the right singular vector
*>          matrix common to [ B11 ; 0 ] and [ B21 ; 0 ].
*> \endverbatim
*>
*> \param[in] LDV1T
*> \verbatim
*>          LDV1T is INTEGER
*>          The leading dimension of the array V1T, LDV1T >= MAX(1,Q).
*> \endverbatim
*>
*> \param[in,out] V2T
*> \verbatim
*>          V2T is DOUBLE PRECISION array, dimension (LDV2T,M-Q)
*>          On entry, an (M-Q)-by-(M-Q) matrix. On exit, V2T is
*>          premultiplied by the transpose of the right
*>          singular vector matrix common to [ B12 0 0 ; 0 -I 0 ] and
*>          [ B22 0 0 ; 0 0 I ].
*> \endverbatim
*>
*> \param[in] LDV2T
*> \verbatim
*>          LDV2T is INTEGER
*>          The leading dimension of the array V2T, LDV2T >= MAX(1,M-Q).
*> \endverbatim
*>
*> \param[out] B11D
*> \verbatim
*>          B11D is DOUBLE PRECISION array, dimension (Q)
*>          When DBBCSD converges, B11D contains the cosines of THETA(1),
*>          ..., THETA(Q). If DBBCSD fails to converge, then B11D
*>          contains the diagonal of the partially reduced top-left
*>          block.
*> \endverbatim
*>
*> \param[out] B11E
*> \verbatim
*>          B11E is DOUBLE PRECISION array, dimension (Q-1)
*>          When DBBCSD converges, B11E contains zeros. If DBBCSD fails
*>          to converge, then B11E contains the superdiagonal of the
*>          partially reduced top-left block.
*> \endverbatim
*>
*> \param[out] B12D
*> \verbatim
*>          B12D is DOUBLE PRECISION array, dimension (Q)
*>          When DBBCSD converges, B12D contains the negative sines of
*>          THETA(1), ..., THETA(Q). If DBBCSD fails to converge, then
*>          B12D contains the diagonal of the partially reduced top-right
*>          block.
*> \endverbatim
*>
*> \param[out] B12E
*> \verbatim
*>          B12E is DOUBLE PRECISION array, dimension (Q-1)
*>          When DBBCSD converges, B12E contains zeros. If DBBCSD fails
*>          to converge, then B12E contains the subdiagonal of the
*>          partially reduced top-right block.
*> \endverbatim
*>
*> \param[out] B21D
*> \verbatim
*>          B21D is DOUBLE PRECISION  array, dimension (Q)
*>          When DBBCSD converges, B21D contains the negative sines of
*>          THETA(1), ..., THETA(Q). If DBBCSD fails to converge, then
*>          B21D contains the diagonal of the partially reduced bottom-left
*>          block.
*> \endverbatim
*>
*> \param[out] B21E
*> \verbatim
*>          B21E is DOUBLE PRECISION  array, dimension (Q-1)
*>          When DBBCSD converges, B21E contains zeros. If DBBCSD fails
*>          to converge, then B21E contains the subdiagonal of the
*>          partially reduced bottom-left block.
*> \endverbatim
*>
*> \param[out] B22D
*> \verbatim
*>          B22D is DOUBLE PRECISION  array, dimension (Q)
*>          When DBBCSD converges, B22D contains the negative sines of
*>          THETA(1), ..., THETA(Q). If DBBCSD fails to converge, then
*>          B22D contains the diagonal of the partially reduced bottom-right
*>          block.
*> \endverbatim
*>
*> \param[out] B22E
*> \verbatim
*>          B22E is DOUBLE PRECISION  array, dimension (Q-1)
*>          When DBBCSD converges, B22E contains zeros. If DBBCSD fails
*>          to converge, then B22E contains the subdiagonal of the
*>          partially reduced bottom-right block.
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK))
*>          On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
*> \endverbatim
*>
*> \param[in] LWORK
*> \verbatim
*>          LWORK is INTEGER
*>          The dimension of the array WORK. LWORK >= MAX(1,8*Q).
*>
*>          If LWORK = -1, then a workspace query is assumed; the
*>          routine only calculates the optimal size of the WORK array,
*>          returns this value as the first entry of the work array, and
*>          no error message related to LWORK is issued by XERBLA.
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit.
*>          < 0:  if INFO = -i, the i-th argument had an illegal value.
*>          > 0:  if DBBCSD did not converge, INFO specifies the number
*>                of nonzero entries in PHI, and B11D, B11E, etc.,
*>                contain the partially reduced matrix.
*> \endverbatim
*
*> \par Internal Parameters:
*  =========================
*>
*> \verbatim
*>  TOLMUL  DOUBLE PRECISION, default = MAX(10,MIN(100,EPS**(-1/8)))
*>          TOLMUL controls the convergence criterion of the QR loop.
*>          Angles THETA(i), PHI(i) are rounded to 0 or PI/2 when they
*>          are within TOLMUL*EPS of either bound.
*> \endverbatim
*
*> \par References:
*  ================
*>
*>  [1] Brian D. Sutton. Computing the complete CS decomposition. Numer.
*>      Algorithms, 50(1):33-65, 2009.
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date June 2016
*
*> \ingroup doubleOTHERcomputational
*
*  =====================================================================
      SUBROUTINE DBBCSD( JOBU1, JOBU2, JOBV1T, JOBV2T, TRANS, M, P, Q,
     $                   THETA, PHI, U1, LDU1, U2, LDU2, V1T, LDV1T,
     $                   V2T, LDV2T, B11D, B11E, B12D, B12E, B21D, B21E,
     $                   B22D, B22E, WORK, LWORK, INFO )
*
*  -- LAPACK computational routine (version 3.7.1) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     June 2016
*
*     .. Scalar Arguments ..
      CHARACTER          JOBU1, JOBU2, JOBV1T, JOBV2T, TRANS
      INTEGER            INFO, LDU1, LDU2, LDV1T, LDV2T, LWORK, M, P, Q
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   B11D( * ), B11E( * ), B12D( * ), B12E( * ),
     $                   B21D( * ), B21E( * ), B22D( * ), B22E( * ),
     $                   PHI( * ), THETA( * ), WORK( * )
      DOUBLE PRECISION   U1( LDU1, * ), U2( LDU2, * ), V1T( LDV1T, * ),
     $                   V2T( LDV2T, * )
*     ..
*
*  ===================================================================
*
*     .. Parameters ..
      INTEGER            MAXITR
      PARAMETER          ( MAXITR = 6 )
      DOUBLE PRECISION   HUNDRED, MEIGHTH, ONE, PIOVER2, TEN, ZERO
      PARAMETER          ( HUNDRED = 100.0D0, MEIGHTH = -0.125D0,
     $                     ONE = 1.0D0, PIOVER2 = 1.57079632679489662D0,
     $                     TEN = 10.0D0, ZERO = 0.0D0 )
      DOUBLE PRECISION   NEGONE
      PARAMETER          ( NEGONE = -1.0D0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            COLMAJOR, LQUERY, RESTART11, RESTART12,
     $                   RESTART21, RESTART22, WANTU1, WANTU2, WANTV1T,
     $                   WANTV2T
      INTEGER            I, IMIN, IMAX, ITER, IU1CS, IU1SN, IU2CS,
     $                   IU2SN, IV1TCS, IV1TSN, IV2TCS, IV2TSN, J,
     $                   LWORKMIN, LWORKOPT, MAXIT, MINI
      DOUBLE PRECISION   B11BULGE, B12BULGE, B21BULGE, B22BULGE, DUMMY,
     $                   EPS, MU, NU, R, SIGMA11, SIGMA21,
     $                   TEMP, THETAMAX, THETAMIN, THRESH, TOL, TOLMUL,
     $                   UNFL, X1, X2, Y1, Y2
*
*     .. External Subroutines ..
      EXTERNAL           DLASR, DSCAL, DSWAP, DLARTGP, DLARTGS, DLAS2,
     $                   XERBLA
*     ..
*     .. External Functions ..
      DOUBLE PRECISION   DLAMCH
      LOGICAL            LSAME
      EXTERNAL           LSAME, DLAMCH
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          ABS, ATAN2, COS, MAX, MIN, SIN, SQRT
*     ..
*     .. Executable Statements ..
*
*     Test input arguments
*
      INFO = 0
      LQUERY = LWORK .EQ. -1
      WANTU1 = LSAME( JOBU1, 'Y' )
      WANTU2 = LSAME( JOBU2, 'Y' )
      WANTV1T = LSAME( JOBV1T, 'Y' )
      WANTV2T = LSAME( JOBV2T, 'Y' )
      COLMAJOR = .NOT. LSAME( TRANS, 'T' )
*
      IF( M .LT. 0 ) THEN
         INFO = -6
      ELSE IF( P .LT. 0 .OR. P .GT. M ) THEN
         INFO = -7
      ELSE IF( Q .LT. 0 .OR. Q .GT. M ) THEN
         INFO = -8
      ELSE IF( Q .GT. P .OR. Q .GT. M-P .OR. Q .GT. M-Q ) THEN
         INFO = -8
      ELSE IF( WANTU1 .AND. LDU1 .LT. P ) THEN
         INFO = -12
      ELSE IF( WANTU2 .AND. LDU2 .LT. M-P ) THEN
         INFO = -14
      ELSE IF( WANTV1T .AND. LDV1T .LT. Q ) THEN
         INFO = -16
      ELSE IF( WANTV2T .AND. LDV2T .LT. M-Q ) THEN
         INFO = -18
      END IF
*
*     Quick return if Q = 0
*
      IF( INFO .EQ. 0 .AND. Q .EQ. 0 ) THEN
         LWORKMIN = 1
         WORK(1) = LWORKMIN
         RETURN
      END IF
*
*     Compute workspace
*
      IF( INFO .EQ. 0 ) THEN
         IU1CS = 1
         IU1SN = IU1CS + Q
         IU2CS = IU1SN + Q
         IU2SN = IU2CS + Q
         IV1TCS = IU2SN + Q
         IV1TSN = IV1TCS + Q
         IV2TCS = IV1TSN + Q
         IV2TSN = IV2TCS + Q
         LWORKOPT = IV2TSN + Q - 1
         LWORKMIN = LWORKOPT
         WORK(1) = LWORKOPT
         IF( LWORK .LT. LWORKMIN .AND. .NOT. LQUERY ) THEN
            INFO = -28
         END IF
      END IF
*
      IF( INFO .NE. 0 ) THEN
         CALL XERBLA( 'DBBCSD', -INFO )
         RETURN
      ELSE IF( LQUERY ) THEN
         RETURN
      END IF
*
*     Get machine constants
*
      EPS = DLAMCH( 'Epsilon' )
      UNFL = DLAMCH( 'Safe minimum' )
      TOLMUL = MAX( TEN, MIN( HUNDRED, EPS**MEIGHTH ) )
      TOL = TOLMUL*EPS
      THRESH = MAX( TOL, MAXITR*Q*Q*UNFL )
*
*     Test for negligible sines or cosines
*
      DO I = 1, Q
         IF( THETA(I) .LT. THRESH ) THEN
            THETA(I) = ZERO
         ELSE IF( THETA(I) .GT. PIOVER2-THRESH ) THEN
            THETA(I) = PIOVER2
         END IF
      END DO
      DO I = 1, Q-1
         IF( PHI(I) .LT. THRESH ) THEN
            PHI(I) = ZERO
         ELSE IF( PHI(I) .GT. PIOVER2-THRESH ) THEN
            PHI(I) = PIOVER2
         END IF
      END DO
*
*     Initial deflation
*
      IMAX = Q
      DO WHILE( IMAX .GT. 1 )
         IF( PHI(IMAX-1) .NE. ZERO ) THEN
            EXIT
         END IF
         IMAX = IMAX - 1
      END DO
      IMIN = IMAX - 1
      IF  ( IMIN .GT. 1 ) THEN
         DO WHILE( PHI(IMIN-1) .NE. ZERO )
            IMIN = IMIN - 1
            IF  ( IMIN .LE. 1 ) EXIT
         END DO
      END IF
*
*     Initialize iteration counter
*
      MAXIT = MAXITR*Q*Q
      ITER = 0
*
*     Begin main iteration loop
*
      DO WHILE( IMAX .GT. 1 )
*
*        Compute the matrix entries
*
         B11D(IMIN) = COS( THETA(IMIN) )
         B21D(IMIN) = -SIN( THETA(IMIN) )
         DO I = IMIN, IMAX - 1
            B11E(I) = -SIN( THETA(I) ) * SIN( PHI(I) )
            B11D(I+1) = COS( THETA(I+1) ) * COS( PHI(I) )
            B12D(I) = SIN( THETA(I) ) * COS( PHI(I) )
            B12E(I) = COS( THETA(I+1) ) * SIN( PHI(I) )
            B21E(I) = -COS( THETA(I) ) * SIN( PHI(I) )
            B21D(I+1) = -SIN( THETA(I+1) ) * COS( PHI(I) )
            B22D(I) = COS( THETA(I) ) * COS( PHI(I) )
            B22E(I) = -SIN( THETA(I+1) ) * SIN( PHI(I) )
         END DO
         B12D(IMAX) = SIN( THETA(IMAX) )
         B22D(IMAX) = COS( THETA(IMAX) )
*
*        Abort if not converging; otherwise, increment ITER
*
         IF( ITER .GT. MAXIT ) THEN
            INFO = 0
            DO I = 1, Q
               IF( PHI(I) .NE. ZERO )
     $            INFO = INFO + 1
            END DO
            RETURN
         END IF
*
         ITER = ITER + IMAX - IMIN
*
*        Compute shifts
*
         THETAMAX = THETA(IMIN)
         THETAMIN = THETA(IMIN)
         DO I = IMIN+1, IMAX
            IF( THETA(I) > THETAMAX )
     $         THETAMAX = THETA(I)
            IF( THETA(I) < THETAMIN )
     $         THETAMIN = THETA(I)
         END DO
*
         IF( THETAMAX .GT. PIOVER2 - THRESH ) THEN
*
*           Zero on diagonals of B11 and B22; induce deflation with a
*           zero shift
*
            MU = ZERO
            NU = ONE
*
         ELSE IF( THETAMIN .LT. THRESH ) THEN
*
*           Zero on diagonals of B12 and B22; induce deflation with a
*           zero shift
*
            MU = ONE
            NU = ZERO
*
         ELSE
*
*           Compute shifts for B11 and B21 and use the lesser
*
            CALL DLAS2( B11D(IMAX-1), B11E(IMAX-1), B11D(IMAX), SIGMA11,
     $                  DUMMY )
            CALL DLAS2( B21D(IMAX-1), B21E(IMAX-1), B21D(IMAX), SIGMA21,
     $                  DUMMY )
*
            IF( SIGMA11 .LE. SIGMA21 ) THEN
               MU = SIGMA11
               NU = SQRT( ONE - MU**2 )
               IF( MU .LT. THRESH ) THEN
                  MU = ZERO
                  NU = ONE
               END IF
            ELSE
               NU = SIGMA21
               MU = SQRT( 1.0 - NU**2 )
               IF( NU .LT. THRESH ) THEN
                  MU = ONE
                  NU = ZERO
               END IF
            END IF
         END IF
*
*        Rotate to produce bulges in B11 and B21
*
         IF( MU .LE. NU ) THEN
            CALL DLARTGS( B11D(IMIN), B11E(IMIN), MU,
     $                    WORK(IV1TCS+IMIN-1), WORK(IV1TSN+IMIN-1) )
         ELSE
            CALL DLARTGS( B21D(IMIN), B21E(IMIN), NU,
     $                    WORK(IV1TCS+IMIN-1), WORK(IV1TSN+IMIN-1) )
         END IF
*
         TEMP = WORK(IV1TCS+IMIN-1)*B11D(IMIN) +
     $          WORK(IV1TSN+IMIN-1)*B11E(IMIN)
         B11E(IMIN) = WORK(IV1TCS+IMIN-1)*B11E(IMIN) -
     $                WORK(IV1TSN+IMIN-1)*B11D(IMIN)
         B11D(IMIN) = TEMP
         B11BULGE = WORK(IV1TSN+IMIN-1)*B11D(IMIN+1)
         B11D(IMIN+1) = WORK(IV1TCS+IMIN-1)*B11D(IMIN+1)
         TEMP = WORK(IV1TCS+IMIN-1)*B21D(IMIN) +
     $          WORK(IV1TSN+IMIN-1)*B21E(IMIN)
         B21E(IMIN) = WORK(IV1TCS+IMIN-1)*B21E(IMIN) -
     $                WORK(IV1TSN+IMIN-1)*B21D(IMIN)
         B21D(IMIN) = TEMP
         B21BULGE = WORK(IV1TSN+IMIN-1)*B21D(IMIN+1)
         B21D(IMIN+1) = WORK(IV1TCS+IMIN-1)*B21D(IMIN+1)
*
*        Compute THETA(IMIN)
*
         THETA( IMIN ) = ATAN2( SQRT( B21D(IMIN)**2+B21BULGE**2 ),
     $                   SQRT( B11D(IMIN)**2+B11BULGE**2 ) )
*
*        Chase the bulges in B11(IMIN+1,IMIN) and B21(IMIN+1,IMIN)
*
         IF( B11D(IMIN)**2+B11BULGE**2 .GT. THRESH**2 ) THEN
            CALL DLARTGP( B11BULGE, B11D(IMIN), WORK(IU1SN+IMIN-1),
     $                    WORK(IU1CS+IMIN-1), R )
         ELSE IF( MU .LE. NU ) THEN
            CALL DLARTGS( B11E( IMIN ), B11D( IMIN + 1 ), MU,
     $                    WORK(IU1CS+IMIN-1), WORK(IU1SN+IMIN-1) )
         ELSE
            CALL DLARTGS( B12D( IMIN ), B12E( IMIN ), NU,
     $                    WORK(IU1CS+IMIN-1), WORK(IU1SN+IMIN-1) )
         END IF
         IF( B21D(IMIN)**2+B21BULGE**2 .GT. THRESH**2 ) THEN
            CALL DLARTGP( B21BULGE, B21D(IMIN), WORK(IU2SN+IMIN-1),
     $                    WORK(IU2CS+IMIN-1), R )
         ELSE IF( NU .LT. MU ) THEN
            CALL DLARTGS( B21E( IMIN ), B21D( IMIN + 1 ), NU,
     $                    WORK(IU2CS+IMIN-1), WORK(IU2SN+IMIN-1) )
         ELSE
            CALL DLARTGS( B22D(IMIN), B22E(IMIN), MU,
     $                    WORK(IU2CS+IMIN-1), WORK(IU2SN+IMIN-1) )
         END IF
         WORK(IU2CS+IMIN-1) = -WORK(IU2CS+IMIN-1)
         WORK(IU2SN+IMIN-1) = -WORK(IU2SN+IMIN-1)
*
         TEMP = WORK(IU1CS+IMIN-1)*B11E(IMIN) +
     $          WORK(IU1SN+IMIN-1)*B11D(IMIN+1)
         B11D(IMIN+1) = WORK(IU1CS+IMIN-1)*B11D(IMIN+1) -
     $                  WORK(IU1SN+IMIN-1)*B11E(IMIN)
         B11E(IMIN) = TEMP
         IF( IMAX .GT. IMIN+1 ) THEN
            B11BULGE = WORK(IU1SN+IMIN-1)*B11E(IMIN+1)
            B11E(IMIN+1) = WORK(IU1CS+IMIN-1)*B11E(IMIN+1)
         END IF
         TEMP = WORK(IU1CS+IMIN-1)*B12D(IMIN) +
     $          WORK(IU1SN+IMIN-1)*B12E(IMIN)
         B12E(IMIN) = WORK(IU1CS+IMIN-1)*B12E(IMIN) -
     $                WORK(IU1SN+IMIN-1)*B12D(IMIN)
         B12D(IMIN) = TEMP
         B12BULGE = WORK(IU1SN+IMIN-1)*B12D(IMIN+1)
         B12D(IMIN+1) = WORK(IU1CS+IMIN-1)*B12D(IMIN+1)
         TEMP = WORK(IU2CS+IMIN-1)*B21E(IMIN) +
     $          WORK(IU2SN+IMIN-1)*B21D(IMIN+1)
         B21D(IMIN+1) = WORK(IU2CS+IMIN-1)*B21D(IMIN+1) -
     $                  WORK(IU2SN+IMIN-1)*B21E(IMIN)
         B21E(IMIN) = TEMP
         IF( IMAX .GT. IMIN+1 ) THEN
            B21BULGE = WORK(IU2SN+IMIN-1)*B21E(IMIN+1)
            B21E(IMIN+1) = WORK(IU2CS+IMIN-1)*B21E(IMIN+1)
         END IF
         TEMP = WORK(IU2CS+IMIN-1)*B22D(IMIN) +
     $          WORK(IU2SN+IMIN-1)*B22E(IMIN)
         B22E(IMIN) = WORK(IU2CS+IMIN-1)*B22E(IMIN) -
     $                WORK(IU2SN+IMIN-1)*B22D(IMIN)
         B22D(IMIN) = TEMP
         B22BULGE = WORK(IU2SN+IMIN-1)*B22D(IMIN+1)
         B22D(IMIN+1) = WORK(IU2CS+IMIN-1)*B22D(IMIN+1)
*
*        Inner loop: chase bulges from B11(IMIN,IMIN+2),
*        B12(IMIN,IMIN+1), B21(IMIN,IMIN+2), and B22(IMIN,IMIN+1) to
*        bottom-right
*
         DO I = IMIN+1, IMAX-1
*
*           Compute PHI(I-1)
*
            X1 = SIN(THETA(I-1))*B11E(I-1) + COS(THETA(I-1))*B21E(I-1)
            X2 = SIN(THETA(I-1))*B11BULGE + COS(THETA(I-1))*B21BULGE
            Y1 = SIN(THETA(I-1))*B12D(I-1) + COS(THETA(I-1))*B22D(I-1)
            Y2 = SIN(THETA(I-1))*B12BULGE + COS(THETA(I-1))*B22BULGE
*
            PHI(I-1) = ATAN2( SQRT(X1**2+X2**2), SQRT(Y1**2+Y2**2) )
*
*           Determine if there are bulges to chase or if a new direct
*           summand has been reached
*
            RESTART11 = B11E(I-1)**2 + B11BULGE**2 .LE. THRESH**2
            RESTART21 = B21E(I-1)**2 + B21BULGE**2 .LE. THRESH**2
            RESTART12 = B12D(I-1)**2 + B12BULGE**2 .LE. THRESH**2
            RESTART22 = B22D(I-1)**2 + B22BULGE**2 .LE. THRESH**2
*
*           If possible, chase bulges from B11(I-1,I+1), B12(I-1,I),
*           B21(I-1,I+1), and B22(I-1,I). If necessary, restart bulge-
*           chasing by applying the original shift again.
*
            IF( .NOT. RESTART11 .AND. .NOT. RESTART21 ) THEN
               CALL DLARTGP( X2, X1, WORK(IV1TSN+I-1), WORK(IV1TCS+I-1),
     $                       R )
            ELSE IF( .NOT. RESTART11 .AND. RESTART21 ) THEN
               CALL DLARTGP( B11BULGE, B11E(I-1), WORK(IV1TSN+I-1),
     $                       WORK(IV1TCS+I-1), R )
            ELSE IF( RESTART11 .AND. .NOT. RESTART21 ) THEN
               CALL DLARTGP( B21BULGE, B21E(I-1), WORK(IV1TSN+I-1),
     $                       WORK(IV1TCS+I-1), R )
            ELSE IF( MU .LE. NU ) THEN
               CALL DLARTGS( B11D(I), B11E(I), MU, WORK(IV1TCS+I-1),
     $                       WORK(IV1TSN+I-1) )
            ELSE
               CALL DLARTGS( B21D(I), B21E(I), NU, WORK(IV1TCS+I-1),
     $                       WORK(IV1TSN+I-1) )
            END IF
            WORK(IV1TCS+I-1) = -WORK(IV1TCS+I-1)
            WORK(IV1TSN+I-1) = -WORK(IV1TSN+I-1)
            IF( .NOT. RESTART12 .AND. .NOT. RESTART22 ) THEN
               CALL DLARTGP( Y2, Y1, WORK(IV2TSN+I-1-1),
     $                       WORK(IV2TCS+I-1-1), R )
            ELSE IF( .NOT. RESTART12 .AND. RESTART22 ) THEN
               CALL DLARTGP( B12BULGE, B12D(I-1), WORK(IV2TSN+I-1-1),
     $                       WORK(IV2TCS+I-1-1), R )
            ELSE IF( RESTART12 .AND. .NOT. RESTART22 ) THEN
               CALL DLARTGP( B22BULGE, B22D(I-1), WORK(IV2TSN+I-1-1),
     $                       WORK(IV2TCS+I-1-1), R )
            ELSE IF( NU .LT. MU ) THEN
               CALL DLARTGS( B12E(I-1), B12D(I), NU, WORK(IV2TCS+I-1-1),
     $                       WORK(IV2TSN+I-1-1) )
            ELSE
               CALL DLARTGS( B22E(I-1), B22D(I), MU, WORK(IV2TCS+I-1-1),
     $                       WORK(IV2TSN+I-1-1) )
            END IF
*
            TEMP = WORK(IV1TCS+I-1)*B11D(I) + WORK(IV1TSN+I-1)*B11E(I)
            B11E(I) = WORK(IV1TCS+I-1)*B11E(I) -
     $                WORK(IV1TSN+I-1)*B11D(I)
            B11D(I) = TEMP
            B11BULGE = WORK(IV1TSN+I-1)*B11D(I+1)
            B11D(I+1) = WORK(IV1TCS+I-1)*B11D(I+1)
            TEMP = WORK(IV1TCS+I-1)*B21D(I) + WORK(IV1TSN+I-1)*B21E(I)
            B21E(I) = WORK(IV1TCS+I-1)*B21E(I) -
     $                WORK(IV1TSN+I-1)*B21D(I)
            B21D(I) = TEMP
            B21BULGE = WORK(IV1TSN+I-1)*B21D(I+1)
            B21D(I+1) = WORK(IV1TCS+I-1)*B21D(I+1)
            TEMP = WORK(IV2TCS+I-1-1)*B12E(I-1) +
     $             WORK(IV2TSN+I-1-1)*B12D(I)
            B12D(I) = WORK(IV2TCS+I-1-1)*B12D(I) -
     $                WORK(IV2TSN+I-1-1)*B12E(I-1)
            B12E(I-1) = TEMP
            B12BULGE = WORK(IV2TSN+I-1-1)*B12E(I)
            B12E(I) = WORK(IV2TCS+I-1-1)*B12E(I)
            TEMP = WORK(IV2TCS+I-1-1)*B22E(I-1) +
     $             WORK(IV2TSN+I-1-1)*B22D(I)
            B22D(I) = WORK(IV2TCS+I-1-1)*B22D(I) -
     $                WORK(IV2TSN+I-1-1)*B22E(I-1)
            B22E(I-1) = TEMP
            B22BULGE = WORK(IV2TSN+I-1-1)*B22E(I)
            B22E(I) = WORK(IV2TCS+I-1-1)*B22E(I)
*
*           Compute THETA(I)
*
            X1 = COS(PHI(I-1))*B11D(I) + SIN(PHI(I-1))*B12E(I-1)
            X2 = COS(PHI(I-1))*B11BULGE + SIN(PHI(I-1))*B12BULGE
            Y1 = COS(PHI(I-1))*B21D(I) + SIN(PHI(I-1))*B22E(I-1)
            Y2 = COS(PHI(I-1))*B21BULGE + SIN(PHI(I-1))*B22BULGE
*
            THETA(I) = ATAN2( SQRT(Y1**2+Y2**2), SQRT(X1**2+X2**2) )
*
*           Determine if there are bulges to chase or if a new direct
*           summand has been reached
*
            RESTART11 =   B11D(I)**2 + B11BULGE**2 .LE. THRESH**2
            RESTART12 = B12E(I-1)**2 + B12BULGE**2 .LE. THRESH**2
            RESTART21 =   B21D(I)**2 + B21BULGE**2 .LE. THRESH**2
            RESTART22 = B22E(I-1)**2 + B22BULGE**2 .LE. THRESH**2
*
*           If possible, chase bulges from B11(I+1,I), B12(I+1,I-1),
*           B21(I+1,I), and B22(I+1,I-1). If necessary, restart bulge-
*           chasing by applying the original shift again.
*
            IF( .NOT. RESTART11 .AND. .NOT. RESTART12 ) THEN
               CALL DLARTGP( X2, X1, WORK(IU1SN+I-1), WORK(IU1CS+I-1),
     $                       R )
            ELSE IF( .NOT. RESTART11 .AND. RESTART12 ) THEN
               CALL DLARTGP( B11BULGE, B11D(I), WORK(IU1SN+I-1),
     $                       WORK(IU1CS+I-1), R )
            ELSE IF( RESTART11 .AND. .NOT. RESTART12 ) THEN
               CALL DLARTGP( B12BULGE, B12E(I-1), WORK(IU1SN+I-1),
     $                       WORK(IU1CS+I-1), R )
            ELSE IF( MU .LE. NU ) THEN
               CALL DLARTGS( B11E(I), B11D(I+1), MU, WORK(IU1CS+I-1),
     $                       WORK(IU1SN+I-1) )
            ELSE
               CALL DLARTGS( B12D(I), B12E(I), NU, WORK(IU1CS+I-1),
     $                       WORK(IU1SN+I-1) )
            END IF
            IF( .NOT. RESTART21 .AND. .NOT. RESTART22 ) THEN
               CALL DLARTGP( Y2, Y1, WORK(IU2SN+I-1), WORK(IU2CS+I-1),
     $                       R )
            ELSE IF( .NOT. RESTART21 .AND. RESTART22 ) THEN
               CALL DLARTGP( B21BULGE, B21D(I), WORK(IU2SN+I-1),
     $                       WORK(IU2CS+I-1), R )
            ELSE IF( RESTART21 .AND. .NOT. RESTART22 ) THEN
               CALL DLARTGP( B22BULGE, B22E(I-1), WORK(IU2SN+I-1),
     $                       WORK(IU2CS+I-1), R )
            ELSE IF( NU .LT. MU ) THEN
               CALL DLARTGS( B21E(I), B21E(I+1), NU, WORK(IU2CS+I-1),
     $                       WORK(IU2SN+I-1) )
            ELSE
               CALL DLARTGS( B22D(I), B22E(I), MU, WORK(IU2CS+I-1),
     $                       WORK(IU2SN+I-1) )
            END IF
            WORK(IU2CS+I-1) = -WORK(IU2CS+I-1)
            WORK(IU2SN+I-1) = -WORK(IU2SN+I-1)
*
            TEMP = WORK(IU1CS+I-1)*B11E(I) + WORK(IU1SN+I-1)*B11D(I+1)
            B11D(I+1) = WORK(IU1CS+I-1)*B11D(I+1) -
     $                  WORK(IU1SN+I-1)*B11E(I)
            B11E(I) = TEMP
            IF( I .LT. IMAX - 1 ) THEN
               B11BULGE = WORK(IU1SN+I-1)*B11E(I+1)
               B11E(I+1) = WORK(IU1CS+I-1)*B11E(I+1)
            END IF
            TEMP = WORK(IU2CS+I-1)*B21E(I) + WORK(IU2SN+I-1)*B21D(I+1)
            B21D(I+1) = WORK(IU2CS+I-1)*B21D(I+1) -
     $                  WORK(IU2SN+I-1)*B21E(I)
            B21E(I) = TEMP
            IF( I .LT. IMAX - 1 ) THEN
               B21BULGE = WORK(IU2SN+I-1)*B21E(I+1)
               B21E(I+1) = WORK(IU2CS+I-1)*B21E(I+1)
            END IF
            TEMP = WORK(IU1CS+I-1)*B12D(I) + WORK(IU1SN+I-1)*B12E(I)
            B12E(I) = WORK(IU1CS+I-1)*B12E(I) - WORK(IU1SN+I-1)*B12D(I)
            B12D(I) = TEMP
            B12BULGE = WORK(IU1SN+I-1)*B12D(I+1)
            B12D(I+1) = WORK(IU1CS+I-1)*B12D(I+1)
            TEMP = WORK(IU2CS+I-1)*B22D(I) + WORK(IU2SN+I-1)*B22E(I)
            B22E(I) = WORK(IU2CS+I-1)*B22E(I) - WORK(IU2SN+I-1)*B22D(I)
            B22D(I) = TEMP
            B22BULGE = WORK(IU2SN+I-1)*B22D(I+1)
            B22D(I+1) = WORK(IU2CS+I-1)*B22D(I+1)
*
         END DO
*
*        Compute PHI(IMAX-1)
*
         X1 = SIN(THETA(IMAX-1))*B11E(IMAX-1) +
     $        COS(THETA(IMAX-1))*B21E(IMAX-1)
         Y1 = SIN(THETA(IMAX-1))*B12D(IMAX-1) +
     $        COS(THETA(IMAX-1))*B22D(IMAX-1)
         Y2 = SIN(THETA(IMAX-1))*B12BULGE + COS(THETA(IMAX-1))*B22BULGE
*
         PHI(IMAX-1) = ATAN2( ABS(X1), SQRT(Y1**2+Y2**2) )
*
*        Chase bulges from B12(IMAX-1,IMAX) and B22(IMAX-1,IMAX)
*
         RESTART12 = B12D(IMAX-1)**2 + B12BULGE**2 .LE. THRESH**2
         RESTART22 = B22D(IMAX-1)**2 + B22BULGE**2 .LE. THRESH**2
*
         IF( .NOT. RESTART12 .AND. .NOT. RESTART22 ) THEN
            CALL DLARTGP( Y2, Y1, WORK(IV2TSN+IMAX-1-1),
     $                    WORK(IV2TCS+IMAX-1-1), R )
         ELSE IF( .NOT. RESTART12 .AND. RESTART22 ) THEN
            CALL DLARTGP( B12BULGE, B12D(IMAX-1), WORK(IV2TSN+IMAX-1-1),
     $                    WORK(IV2TCS+IMAX-1-1), R )
         ELSE IF( RESTART12 .AND. .NOT. RESTART22 ) THEN
            CALL DLARTGP( B22BULGE, B22D(IMAX-1), WORK(IV2TSN+IMAX-1-1),
     $                    WORK(IV2TCS+IMAX-1-1), R )
         ELSE IF( NU .LT. MU ) THEN
            CALL DLARTGS( B12E(IMAX-1), B12D(IMAX), NU,
     $                    WORK(IV2TCS+IMAX-1-1), WORK(IV2TSN+IMAX-1-1) )
         ELSE
            CALL DLARTGS( B22E(IMAX-1), B22D(IMAX), MU,
     $                    WORK(IV2TCS+IMAX-1-1), WORK(IV2TSN+IMAX-1-1) )
         END IF
*
         TEMP = WORK(IV2TCS+IMAX-1-1)*B12E(IMAX-1) +
     $          WORK(IV2TSN+IMAX-1-1)*B12D(IMAX)
         B12D(IMAX) = WORK(IV2TCS+IMAX-1-1)*B12D(IMAX) -
     $                WORK(IV2TSN+IMAX-1-1)*B12E(IMAX-1)
         B12E(IMAX-1) = TEMP
         TEMP = WORK(IV2TCS+IMAX-1-1)*B22E(IMAX-1) +
     $          WORK(IV2TSN+IMAX-1-1)*B22D(IMAX)
         B22D(IMAX) = WORK(IV2TCS+IMAX-1-1)*B22D(IMAX) -
     $                WORK(IV2TSN+IMAX-1-1)*B22E(IMAX-1)
         B22E(IMAX-1) = TEMP
*
*        Update singular vectors
*
         IF( WANTU1 ) THEN
            IF( COLMAJOR ) THEN
               CALL DLASR( 'R', 'V', 'F', P, IMAX-IMIN+1,
     $                     WORK(IU1CS+IMIN-1), WORK(IU1SN+IMIN-1),
     $                     U1(1,IMIN), LDU1 )
            ELSE
               CALL DLASR( 'L', 'V', 'F', IMAX-IMIN+1, P,
     $                     WORK(IU1CS+IMIN-1), WORK(IU1SN+IMIN-1),
     $                     U1(IMIN,1), LDU1 )
            END IF
         END IF
         IF( WANTU2 ) THEN
            IF( COLMAJOR ) THEN
               CALL DLASR( 'R', 'V', 'F', M-P, IMAX-IMIN+1,
     $                     WORK(IU2CS+IMIN-1), WORK(IU2SN+IMIN-1),
     $                     U2(1,IMIN), LDU2 )
            ELSE
               CALL DLASR( 'L', 'V', 'F', IMAX-IMIN+1, M-P,
     $                     WORK(IU2CS+IMIN-1), WORK(IU2SN+IMIN-1),
     $                     U2(IMIN,1), LDU2 )
            END IF
         END IF
         IF( WANTV1T ) THEN
            IF( COLMAJOR ) THEN
               CALL DLASR( 'L', 'V', 'F', IMAX-IMIN+1, Q,
     $                     WORK(IV1TCS+IMIN-1), WORK(IV1TSN+IMIN-1),
     $                     V1T(IMIN,1), LDV1T )
            ELSE
               CALL DLASR( 'R', 'V', 'F', Q, IMAX-IMIN+1,
     $                     WORK(IV1TCS+IMIN-1), WORK(IV1TSN+IMIN-1),
     $                     V1T(1,IMIN), LDV1T )
            END IF
         END IF
         IF( WANTV2T ) THEN
            IF( COLMAJOR ) THEN
               CALL DLASR( 'L', 'V', 'F', IMAX-IMIN+1, M-Q,
     $                     WORK(IV2TCS+IMIN-1), WORK(IV2TSN+IMIN-1),
     $                     V2T(IMIN,1), LDV2T )
            ELSE
               CALL DLASR( 'R', 'V', 'F', M-Q, IMAX-IMIN+1,
     $                     WORK(IV2TCS+IMIN-1), WORK(IV2TSN+IMIN-1),
     $                     V2T(1,IMIN), LDV2T )
            END IF
         END IF
*
*        Fix signs on B11(IMAX-1,IMAX) and B21(IMAX-1,IMAX)
*
         IF( B11E(IMAX-1)+B21E(IMAX-1) .GT. 0 ) THEN
            B11D(IMAX) = -B11D(IMAX)
            B21D(IMAX) = -B21D(IMAX)
            IF( WANTV1T ) THEN
               IF( COLMAJOR ) THEN
                  CALL DSCAL( Q, NEGONE, V1T(IMAX,1), LDV1T )
               ELSE
                  CALL DSCAL( Q, NEGONE, V1T(1,IMAX), 1 )
               END IF
            END IF
         END IF
*
*        Compute THETA(IMAX)
*
         X1 = COS(PHI(IMAX-1))*B11D(IMAX) +
     $        SIN(PHI(IMAX-1))*B12E(IMAX-1)
         Y1 = COS(PHI(IMAX-1))*B21D(IMAX) +
     $        SIN(PHI(IMAX-1))*B22E(IMAX-1)
*
         THETA(IMAX) = ATAN2( ABS(Y1), ABS(X1) )
*
*        Fix signs on B11(IMAX,IMAX), B12(IMAX,IMAX-1), B21(IMAX,IMAX),
*        and B22(IMAX,IMAX-1)
*
         IF( B11D(IMAX)+B12E(IMAX-1) .LT. 0 ) THEN
            B12D(IMAX) = -B12D(IMAX)
            IF( WANTU1 ) THEN
               IF( COLMAJOR ) THEN
                  CALL DSCAL( P, NEGONE, U1(1,IMAX), 1 )
               ELSE
                  CALL DSCAL( P, NEGONE, U1(IMAX,1), LDU1 )
               END IF
            END IF
         END IF
         IF( B21D(IMAX)+B22E(IMAX-1) .GT. 0 ) THEN
            B22D(IMAX) = -B22D(IMAX)
            IF( WANTU2 ) THEN
               IF( COLMAJOR ) THEN
                  CALL DSCAL( M-P, NEGONE, U2(1,IMAX), 1 )
               ELSE
                  CALL DSCAL( M-P, NEGONE, U2(IMAX,1), LDU2 )
               END IF
            END IF
         END IF
*
*        Fix signs on B12(IMAX,IMAX) and B22(IMAX,IMAX)
*
         IF( B12D(IMAX)+B22D(IMAX) .LT. 0 ) THEN
            IF( WANTV2T ) THEN
               IF( COLMAJOR ) THEN
                  CALL DSCAL( M-Q, NEGONE, V2T(IMAX,1), LDV2T )
               ELSE
                  CALL DSCAL( M-Q, NEGONE, V2T(1,IMAX), 1 )
               END IF
            END IF
         END IF
*
*        Test for negligible sines or cosines
*
         DO I = IMIN, IMAX
            IF( THETA(I) .LT. THRESH ) THEN
               THETA(I) = ZERO
            ELSE IF( THETA(I) .GT. PIOVER2-THRESH ) THEN
               THETA(I) = PIOVER2
            END IF
         END DO
         DO I = IMIN, IMAX-1
            IF( PHI(I) .LT. THRESH ) THEN
               PHI(I) = ZERO
            ELSE IF( PHI(I) .GT. PIOVER2-THRESH ) THEN
               PHI(I) = PIOVER2
            END IF
         END DO
*
*        Deflate
*
         IF (IMAX .GT. 1) THEN
            DO WHILE( PHI(IMAX-1) .EQ. ZERO )
               IMAX = IMAX - 1
               IF (IMAX .LE. 1) EXIT
            END DO
         END IF
         IF( IMIN .GT. IMAX - 1 )
     $      IMIN = IMAX - 1
         IF (IMIN .GT. 1) THEN
            DO WHILE (PHI(IMIN-1) .NE. ZERO)
                IMIN = IMIN - 1
                IF (IMIN .LE. 1) EXIT
            END DO
         END IF
*
*        Repeat main iteration loop
*
      END DO
*
*     Postprocessing: order THETA from least to greatest
*
      DO I = 1, Q
*
         MINI = I
         THETAMIN = THETA(I)
         DO J = I+1, Q
            IF( THETA(J) .LT. THETAMIN ) THEN
               MINI = J
               THETAMIN = THETA(J)
            END IF
         END DO
*
         IF( MINI .NE. I ) THEN
            THETA(MINI) = THETA(I)
            THETA(I) = THETAMIN
            IF( COLMAJOR ) THEN
               IF( WANTU1 )
     $            CALL DSWAP( P, U1(1,I), 1, U1(1,MINI), 1 )
               IF( WANTU2 )
     $            CALL DSWAP( M-P, U2(1,I), 1, U2(1,MINI), 1 )
               IF( WANTV1T )
     $            CALL DSWAP( Q, V1T(I,1), LDV1T, V1T(MINI,1), LDV1T )
               IF( WANTV2T )
     $            CALL DSWAP( M-Q, V2T(I,1), LDV2T, V2T(MINI,1),
     $               LDV2T )
            ELSE
               IF( WANTU1 )
     $            CALL DSWAP( P, U1(I,1), LDU1, U1(MINI,1), LDU1 )
               IF( WANTU2 )
     $            CALL DSWAP( M-P, U2(I,1), LDU2, U2(MINI,1), LDU2 )
               IF( WANTV1T )
     $            CALL DSWAP( Q, V1T(1,I), 1, V1T(1,MINI), 1 )
               IF( WANTV2T )
     $            CALL DSWAP( M-Q, V2T(1,I), 1, V2T(1,MINI), 1 )
            END IF
         END IF
*
      END DO
*
      RETURN
*
*     End of DBBCSD
*
      END

*> \brief \b DBDSDC
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DBDSDC + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dbdsdc.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dbdsdc.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dbdsdc.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DBDSDC( UPLO, COMPQ, N, D, E, U, LDU, VT, LDVT, Q, IQ,
*                          WORK, IWORK, INFO )
*
*       .. Scalar Arguments ..
*       CHARACTER          COMPQ, UPLO
*       INTEGER            INFO, LDU, LDVT, N
*       ..
*       .. Array Arguments ..
*       INTEGER            IQ( * ), IWORK( * )
*       DOUBLE PRECISION   D( * ), E( * ), Q( * ), U( LDU, * ),
*      $                   VT( LDVT, * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DBDSDC computes the singular value decomposition (SVD) of a real
*> N-by-N (upper or lower) bidiagonal matrix B:  B = U * S * VT,
*> using a divide and conquer method, where S is a diagonal matrix
*> with non-negative diagonal elements (the singular values of B), and
*> U and VT are orthogonal matrices of left and right singular vectors,
*> respectively. DBDSDC can be used to compute all singular values,
*> and optionally, singular vectors or singular vectors in compact form.
*>
*> This code makes very mild assumptions about floating point
*> arithmetic. It will work on machines with a guard digit in
*> add/subtract, or on those binary machines without guard digits
*> which subtract like the Cray X-MP, Cray Y-MP, Cray C-90, or Cray-2.
*> It could conceivably fail on hexadecimal or decimal machines
*> without guard digits, but we know of none.  See DLASD3 for details.
*>
*> The code currently calls DLASDQ if singular values only are desired.
*> However, it can be slightly modified to compute singular values
*> using the divide and conquer method.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] UPLO
*> \verbatim
*>          UPLO is CHARACTER*1
*>          = 'U':  B is upper bidiagonal.
*>          = 'L':  B is lower bidiagonal.
*> \endverbatim
*>
*> \param[in] COMPQ
*> \verbatim
*>          COMPQ is CHARACTER*1
*>          Specifies whether singular vectors are to be computed
*>          as follows:
*>          = 'N':  Compute singular values only;
*>          = 'P':  Compute singular values and compute singular
*>                  vectors in compact form;
*>          = 'I':  Compute singular values and singular vectors.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The order of the matrix B.  N >= 0.
*> \endverbatim
*>
*> \param[in,out] D
*> \verbatim
*>          D is DOUBLE PRECISION array, dimension (N)
*>          On entry, the n diagonal elements of the bidiagonal matrix B.
*>          On exit, if INFO=0, the singular values of B.
*> \endverbatim
*>
*> \param[in,out] E
*> \verbatim
*>          E is DOUBLE PRECISION array, dimension (N-1)
*>          On entry, the elements of E contain the offdiagonal
*>          elements of the bidiagonal matrix whose SVD is desired.
*>          On exit, E has been destroyed.
*> \endverbatim
*>
*> \param[out] U
*> \verbatim
*>          U is DOUBLE PRECISION array, dimension (LDU,N)
*>          If  COMPQ = 'I', then:
*>             On exit, if INFO = 0, U contains the left singular vectors
*>             of the bidiagonal matrix.
*>          For other values of COMPQ, U is not referenced.
*> \endverbatim
*>
*> \param[in] LDU
*> \verbatim
*>          LDU is INTEGER
*>          The leading dimension of the array U.  LDU >= 1.
*>          If singular vectors are desired, then LDU >= max( 1, N ).
*> \endverbatim
*>
*> \param[out] VT
*> \verbatim
*>          VT is DOUBLE PRECISION array, dimension (LDVT,N)
*>          If  COMPQ = 'I', then:
*>             On exit, if INFO = 0, VT**T contains the right singular
*>             vectors of the bidiagonal matrix.
*>          For other values of COMPQ, VT is not referenced.
*> \endverbatim
*>
*> \param[in] LDVT
*> \verbatim
*>          LDVT is INTEGER
*>          The leading dimension of the array VT.  LDVT >= 1.
*>          If singular vectors are desired, then LDVT >= max( 1, N ).
*> \endverbatim
*>
*> \param[out] Q
*> \verbatim
*>          Q is DOUBLE PRECISION array, dimension (LDQ)
*>          If  COMPQ = 'P', then:
*>             On exit, if INFO = 0, Q and IQ contain the left
*>             and right singular vectors in a compact form,
*>             requiring O(N log N) space instead of 2*N**2.
*>             In particular, Q contains all the DOUBLE PRECISION data in
*>             LDQ >= N*(11 + 2*SMLSIZ + 8*INT(LOG_2(N/(SMLSIZ+1))))
*>             words of memory, where SMLSIZ is returned by ILAENV and
*>             is equal to the maximum size of the subproblems at the
*>             bottom of the computation tree (usually about 25).
*>          For other values of COMPQ, Q is not referenced.
*> \endverbatim
*>
*> \param[out] IQ
*> \verbatim
*>          IQ is INTEGER array, dimension (LDIQ)
*>          If  COMPQ = 'P', then:
*>             On exit, if INFO = 0, Q and IQ contain the left
*>             and right singular vectors in a compact form,
*>             requiring O(N log N) space instead of 2*N**2.
*>             In particular, IQ contains all INTEGER data in
*>             LDIQ >= N*(3 + 3*INT(LOG_2(N/(SMLSIZ+1))))
*>             words of memory, where SMLSIZ is returned by ILAENV and
*>             is equal to the maximum size of the subproblems at the
*>             bottom of the computation tree (usually about 25).
*>          For other values of COMPQ, IQ is not referenced.
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK))
*>          If COMPQ = 'N' then LWORK >= (4 * N).
*>          If COMPQ = 'P' then LWORK >= (6 * N).
*>          If COMPQ = 'I' then LWORK >= (3 * N**2 + 4 * N).
*> \endverbatim
*>
*> \param[out] IWORK
*> \verbatim
*>          IWORK is INTEGER array, dimension (8*N)
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit.
*>          < 0:  if INFO = -i, the i-th argument had an illegal value.
*>          > 0:  The algorithm failed to compute a singular value.
*>                The update process of divide and conquer failed.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date June 2016
*
*> \ingroup auxOTHERcomputational
*
*> \par Contributors:
*  ==================
*>
*>     Ming Gu and Huan Ren, Computer Science Division, University of
*>     California at Berkeley, USA
*>
*  =====================================================================
      SUBROUTINE DBDSDC( UPLO, COMPQ, N, D, E, U, LDU, VT, LDVT, Q, IQ,
     $                   WORK, IWORK, INFO )
*
*  -- LAPACK computational routine (version 3.7.1) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     June 2016
*
*     .. Scalar Arguments ..
      CHARACTER          COMPQ, UPLO
      INTEGER            INFO, LDU, LDVT, N
*     ..
*     .. Array Arguments ..
      INTEGER            IQ( * ), IWORK( * )
      DOUBLE PRECISION   D( * ), E( * ), Q( * ), U( LDU, * ),
     $                   VT( LDVT, * ), WORK( * )
*     ..
*
*  =====================================================================
*  Changed dimension statement in comment describing E from (N) to
*  (N-1).  Sven, 17 Feb 05.
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ZERO, ONE, TWO
      PARAMETER          ( ZERO = 0.0D+0, ONE = 1.0D+0, TWO = 2.0D+0 )
*     ..
*     .. Local Scalars ..
      INTEGER            DIFL, DIFR, GIVCOL, GIVNUM, GIVPTR, I, IC,
     $                   ICOMPQ, IERR, II, IS, IU, IUPLO, IVT, J, K, KK,
     $                   MLVL, NM1, NSIZE, PERM, POLES, QSTART, SMLSIZ,
     $                   SMLSZP, SQRE, START, WSTART, Z
      DOUBLE PRECISION   CS, EPS, ORGNRM, P, R, SN
*     ..
*     .. External Functions ..
      LOGICAL            LSAME
      INTEGER            ILAENV
      DOUBLE PRECISION   DLAMCH, DLANST
      EXTERNAL           LSAME, ILAENV, DLAMCH, DLANST
*     ..
*     .. External Subroutines ..
      EXTERNAL           DCOPY, DLARTG, DLASCL, DLASD0, DLASDA, DLASDQ,
     $                   DLASET, DLASR, DSWAP, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          ABS, DBLE, INT, LOG, SIGN
*     ..
*     .. Executable Statements ..
*
*     Test the input parameters.
*
      INFO = 0
*
      IUPLO = 0
      IF( LSAME( UPLO, 'U' ) )
     $   IUPLO = 1
      IF( LSAME( UPLO, 'L' ) )
     $   IUPLO = 2
      IF( LSAME( COMPQ, 'N' ) ) THEN
         ICOMPQ = 0
      ELSE IF( LSAME( COMPQ, 'P' ) ) THEN
         ICOMPQ = 1
      ELSE IF( LSAME( COMPQ, 'I' ) ) THEN
         ICOMPQ = 2
      ELSE
         ICOMPQ = -1
      END IF
      IF( IUPLO.EQ.0 ) THEN
         INFO = -1
      ELSE IF( ICOMPQ.LT.0 ) THEN
         INFO = -2
      ELSE IF( N.LT.0 ) THEN
         INFO = -3
      ELSE IF( ( LDU.LT.1 ) .OR. ( ( ICOMPQ.EQ.2 ) .AND. ( LDU.LT.
     $         N ) ) ) THEN
         INFO = -7
      ELSE IF( ( LDVT.LT.1 ) .OR. ( ( ICOMPQ.EQ.2 ) .AND. ( LDVT.LT.
     $         N ) ) ) THEN
         INFO = -9
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DBDSDC', -INFO )
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( N.EQ.0 )
     $   RETURN
      SMLSIZ = ILAENV( 9, 'DBDSDC', ' ', 0, 0, 0, 0 )
      IF( N.EQ.1 ) THEN
         IF( ICOMPQ.EQ.1 ) THEN
            Q( 1 ) = SIGN( ONE, D( 1 ) )
            Q( 1+SMLSIZ*N ) = ONE
         ELSE IF( ICOMPQ.EQ.2 ) THEN
            U( 1, 1 ) = SIGN( ONE, D( 1 ) )
            VT( 1, 1 ) = ONE
         END IF
         D( 1 ) = ABS( D( 1 ) )
         RETURN
      END IF
      NM1 = N - 1
*
*     If matrix lower bidiagonal, rotate to be upper bidiagonal
*     by applying Givens rotations on the left
*
      WSTART = 1
      QSTART = 3
      IF( ICOMPQ.EQ.1 ) THEN
         CALL DCOPY( N, D, 1, Q( 1 ), 1 )
         CALL DCOPY( N-1, E, 1, Q( N+1 ), 1 )
      END IF
      IF( IUPLO.EQ.2 ) THEN
         QSTART = 5
         IF( ICOMPQ .EQ. 2 ) WSTART = 2*N - 1
         DO 10 I = 1, N - 1
            CALL DLARTG( D( I ), E( I ), CS, SN, R )
            D( I ) = R
            E( I ) = SN*D( I+1 )
            D( I+1 ) = CS*D( I+1 )
            IF( ICOMPQ.EQ.1 ) THEN
               Q( I+2*N ) = CS
               Q( I+3*N ) = SN
            ELSE IF( ICOMPQ.EQ.2 ) THEN
               WORK( I ) = CS
               WORK( NM1+I ) = -SN
            END IF
   10    CONTINUE
      END IF
*
*     If ICOMPQ = 0, use DLASDQ to compute the singular values.
*
      IF( ICOMPQ.EQ.0 ) THEN
*        Ignore WSTART, instead using WORK( 1 ), since the two vectors
*        for CS and -SN above are added only if ICOMPQ == 2,
*        and adding them exceeds documented WORK size of 4*n.
         CALL DLASDQ( 'U', 0, N, 0, 0, 0, D, E, VT, LDVT, U, LDU, U,
     $                LDU, WORK( 1 ), INFO )
         GO TO 40
      END IF
*
*     If N is smaller than the minimum divide size SMLSIZ, then solve
*     the problem with another solver.
*
      IF( N.LE.SMLSIZ ) THEN
         IF( ICOMPQ.EQ.2 ) THEN
            CALL DLASET( 'A', N, N, ZERO, ONE, U, LDU )
            CALL DLASET( 'A', N, N, ZERO, ONE, VT, LDVT )
            CALL DLASDQ( 'U', 0, N, N, N, 0, D, E, VT, LDVT, U, LDU, U,
     $                   LDU, WORK( WSTART ), INFO )
         ELSE IF( ICOMPQ.EQ.1 ) THEN
            IU = 1
            IVT = IU + N
            CALL DLASET( 'A', N, N, ZERO, ONE, Q( IU+( QSTART-1 )*N ),
     $                   N )
            CALL DLASET( 'A', N, N, ZERO, ONE, Q( IVT+( QSTART-1 )*N ),
     $                   N )
            CALL DLASDQ( 'U', 0, N, N, N, 0, D, E,
     $                   Q( IVT+( QSTART-1 )*N ), N,
     $                   Q( IU+( QSTART-1 )*N ), N,
     $                   Q( IU+( QSTART-1 )*N ), N, WORK( WSTART ),
     $                   INFO )
         END IF
         GO TO 40
      END IF
*
      IF( ICOMPQ.EQ.2 ) THEN
         CALL DLASET( 'A', N, N, ZERO, ONE, U, LDU )
         CALL DLASET( 'A', N, N, ZERO, ONE, VT, LDVT )
      END IF
*
*     Scale.
*
      ORGNRM = DLANST( 'M', N, D, E )
      IF( ORGNRM.EQ.ZERO )
     $   RETURN
      CALL DLASCL( 'G', 0, 0, ORGNRM, ONE, N, 1, D, N, IERR )
      CALL DLASCL( 'G', 0, 0, ORGNRM, ONE, NM1, 1, E, NM1, IERR )
*
      EPS = (0.9D+0)*DLAMCH( 'Epsilon' )
*
      MLVL = INT( LOG( DBLE( N ) / DBLE( SMLSIZ+1 ) ) / LOG( TWO ) ) + 1
      SMLSZP = SMLSIZ + 1
*
      IF( ICOMPQ.EQ.1 ) THEN
         IU = 1
         IVT = 1 + SMLSIZ
         DIFL = IVT + SMLSZP
         DIFR = DIFL + MLVL
         Z = DIFR + MLVL*2
         IC = Z + MLVL
         IS = IC + 1
         POLES = IS + 1
         GIVNUM = POLES + 2*MLVL
*
         K = 1
         GIVPTR = 2
         PERM = 3
         GIVCOL = PERM + MLVL
      END IF
*
      DO 20 I = 1, N
         IF( ABS( D( I ) ).LT.EPS ) THEN
            D( I ) = SIGN( EPS, D( I ) )
         END IF
   20 CONTINUE
*
      START = 1
      SQRE = 0
*
      DO 30 I = 1, NM1
         IF( ( ABS( E( I ) ).LT.EPS ) .OR. ( I.EQ.NM1 ) ) THEN
*
*           Subproblem found. First determine its size and then
*           apply divide and conquer on it.
*
            IF( I.LT.NM1 ) THEN
*
*              A subproblem with E(I) small for I < NM1.
*
               NSIZE = I - START + 1
            ELSE IF( ABS( E( I ) ).GE.EPS ) THEN
*
*              A subproblem with E(NM1) not too small but I = NM1.
*
               NSIZE = N - START + 1
            ELSE
*
*              A subproblem with E(NM1) small. This implies an
*              1-by-1 subproblem at D(N). Solve this 1-by-1 problem
*              first.
*
               NSIZE = I - START + 1
               IF( ICOMPQ.EQ.2 ) THEN
                  U( N, N ) = SIGN( ONE, D( N ) )
                  VT( N, N ) = ONE
               ELSE IF( ICOMPQ.EQ.1 ) THEN
                  Q( N+( QSTART-1 )*N ) = SIGN( ONE, D( N ) )
                  Q( N+( SMLSIZ+QSTART-1 )*N ) = ONE
               END IF
               D( N ) = ABS( D( N ) )
            END IF
            IF( ICOMPQ.EQ.2 ) THEN
               CALL DLASD0( NSIZE, SQRE, D( START ), E( START ),
     $                      U( START, START ), LDU, VT( START, START ),
     $                      LDVT, SMLSIZ, IWORK, WORK( WSTART ), INFO )
            ELSE
               CALL DLASDA( ICOMPQ, SMLSIZ, NSIZE, SQRE, D( START ),
     $                      E( START ), Q( START+( IU+QSTART-2 )*N ), N,
     $                      Q( START+( IVT+QSTART-2 )*N ),
     $                      IQ( START+K*N ), Q( START+( DIFL+QSTART-2 )*
     $                      N ), Q( START+( DIFR+QSTART-2 )*N ),
     $                      Q( START+( Z+QSTART-2 )*N ),
     $                      Q( START+( POLES+QSTART-2 )*N ),
     $                      IQ( START+GIVPTR*N ), IQ( START+GIVCOL*N ),
     $                      N, IQ( START+PERM*N ),
     $                      Q( START+( GIVNUM+QSTART-2 )*N ),
     $                      Q( START+( IC+QSTART-2 )*N ),
     $                      Q( START+( IS+QSTART-2 )*N ),
     $                      WORK( WSTART ), IWORK, INFO )
            END IF
            IF( INFO.NE.0 ) THEN
               RETURN
            END IF
            START = I + 1
         END IF
   30 CONTINUE
*
*     Unscale
*
      CALL DLASCL( 'G', 0, 0, ONE, ORGNRM, N, 1, D, N, IERR )
   40 CONTINUE
*
*     Use Selection Sort to minimize swaps of singular vectors
*
      DO 60 II = 2, N
         I = II - 1
         KK = I
         P = D( I )
         DO 50 J = II, N
            IF( D( J ).GT.P ) THEN
               KK = J
               P = D( J )
            END IF
   50    CONTINUE
         IF( KK.NE.I ) THEN
            D( KK ) = D( I )
            D( I ) = P
            IF( ICOMPQ.EQ.1 ) THEN
               IQ( I ) = KK
            ELSE IF( ICOMPQ.EQ.2 ) THEN
               CALL DSWAP( N, U( 1, I ), 1, U( 1, KK ), 1 )
               CALL DSWAP( N, VT( I, 1 ), LDVT, VT( KK, 1 ), LDVT )
            END IF
         ELSE IF( ICOMPQ.EQ.1 ) THEN
            IQ( I ) = I
         END IF
   60 CONTINUE
*
*     If ICOMPQ = 1, use IQ(N,1) as the indicator for UPLO
*
      IF( ICOMPQ.EQ.1 ) THEN
         IF( IUPLO.EQ.1 ) THEN
            IQ( N ) = 1
         ELSE
            IQ( N ) = 0
         END IF
      END IF
*
*     If B is lower bidiagonal, update U by those Givens rotations
*     which rotated B to be upper bidiagonal
*
      IF( ( IUPLO.EQ.2 ) .AND. ( ICOMPQ.EQ.2 ) )
     $   CALL DLASR( 'L', 'V', 'B', N, N, WORK( 1 ), WORK( N ), U, LDU )
*
      RETURN
*
*     End of DBDSDC
*
      END
*> \brief \b DBDSQR
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DBDSQR + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dbdsqr.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dbdsqr.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dbdsqr.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DBDSQR( UPLO, N, NCVT, NRU, NCC, D, E, VT, LDVT, U,
*                          LDU, C, LDC, WORK, INFO )
*
*       .. Scalar Arguments ..
*       CHARACTER          UPLO
*       INTEGER            INFO, LDC, LDU, LDVT, N, NCC, NCVT, NRU
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   C( LDC, * ), D( * ), E( * ), U( LDU, * ),
*      $                   VT( LDVT, * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DBDSQR computes the singular values and, optionally, the right and/or
*> left singular vectors from the singular value decomposition (SVD) of
*> a real N-by-N (upper or lower) bidiagonal matrix B using the implicit
*> zero-shift QR algorithm.  The SVD of B has the form
*>
*>    B = Q * S * P**T
*>
*> where S is the diagonal matrix of singular values, Q is an orthogonal
*> matrix of left singular vectors, and P is an orthogonal matrix of
*> right singular vectors.  If left singular vectors are requested, this
*> subroutine actually returns U*Q instead of Q, and, if right singular
*> vectors are requested, this subroutine returns P**T*VT instead of
*> P**T, for given real input matrices U and VT.  When U and VT are the
*> orthogonal matrices that reduce a general matrix A to bidiagonal
*> form:  A = U*B*VT, as computed by DGEBRD, then
*>
*>    A = (U*Q) * S * (P**T*VT)
*>
*> is the SVD of A.  Optionally, the subroutine may also compute Q**T*C
*> for a given real input matrix C.
*>
*> See "Computing  Small Singular Values of Bidiagonal Matrices With
*> Guaranteed High Relative Accuracy," by J. Demmel and W. Kahan,
*> LAPACK Working Note #3 (or SIAM J. Sci. Statist. Comput. vol. 11,
*> no. 5, pp. 873-912, Sept 1990) and
*> "Accurate singular values and differential qd algorithms," by
*> B. Parlett and V. Fernando, Technical Report CPAM-554, Mathematics
*> Department, University of California at Berkeley, July 1992
*> for a detailed description of the algorithm.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] UPLO
*> \verbatim
*>          UPLO is CHARACTER*1
*>          = 'U':  B is upper bidiagonal;
*>          = 'L':  B is lower bidiagonal.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The order of the matrix B.  N >= 0.
*> \endverbatim
*>
*> \param[in] NCVT
*> \verbatim
*>          NCVT is INTEGER
*>          The number of columns of the matrix VT. NCVT >= 0.
*> \endverbatim
*>
*> \param[in] NRU
*> \verbatim
*>          NRU is INTEGER
*>          The number of rows of the matrix U. NRU >= 0.
*> \endverbatim
*>
*> \param[in] NCC
*> \verbatim
*>          NCC is INTEGER
*>          The number of columns of the matrix C. NCC >= 0.
*> \endverbatim
*>
*> \param[in,out] D
*> \verbatim
*>          D is DOUBLE PRECISION array, dimension (N)
*>          On entry, the n diagonal elements of the bidiagonal matrix B.
*>          On exit, if INFO=0, the singular values of B in decreasing
*>          order.
*> \endverbatim
*>
*> \param[in,out] E
*> \verbatim
*>          E is DOUBLE PRECISION array, dimension (N-1)
*>          On entry, the N-1 offdiagonal elements of the bidiagonal
*>          matrix B.
*>          On exit, if INFO = 0, E is destroyed; if INFO > 0, D and E
*>          will contain the diagonal and superdiagonal elements of a
*>          bidiagonal matrix orthogonally equivalent to the one given
*>          as input.
*> \endverbatim
*>
*> \param[in,out] VT
*> \verbatim
*>          VT is DOUBLE PRECISION array, dimension (LDVT, NCVT)
*>          On entry, an N-by-NCVT matrix VT.
*>          On exit, VT is overwritten by P**T * VT.
*>          Not referenced if NCVT = 0.
*> \endverbatim
*>
*> \param[in] LDVT
*> \verbatim
*>          LDVT is INTEGER
*>          The leading dimension of the array VT.
*>          LDVT >= max(1,N) if NCVT > 0; LDVT >= 1 if NCVT = 0.
*> \endverbatim
*>
*> \param[in,out] U
*> \verbatim
*>          U is DOUBLE PRECISION array, dimension (LDU, N)
*>          On entry, an NRU-by-N matrix U.
*>          On exit, U is overwritten by U * Q.
*>          Not referenced if NRU = 0.
*> \endverbatim
*>
*> \param[in] LDU
*> \verbatim
*>          LDU is INTEGER
*>          The leading dimension of the array U.  LDU >= max(1,NRU).
*> \endverbatim
*>
*> \param[in,out] C
*> \verbatim
*>          C is DOUBLE PRECISION array, dimension (LDC, NCC)
*>          On entry, an N-by-NCC matrix C.
*>          On exit, C is overwritten by Q**T * C.
*>          Not referenced if NCC = 0.
*> \endverbatim
*>
*> \param[in] LDC
*> \verbatim
*>          LDC is INTEGER
*>          The leading dimension of the array C.
*>          LDC >= max(1,N) if NCC > 0; LDC >=1 if NCC = 0.
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (4*N)
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  If INFO = -i, the i-th argument had an illegal value
*>          > 0:
*>             if NCVT = NRU = NCC = 0,
*>                = 1, a split was marked by a positive value in E
*>                = 2, current block of Z not diagonalized after 30*N
*>                     iterations (in inner while loop)
*>                = 3, termination criterion of outer while loop not met
*>                     (program created more than N unreduced blocks)
*>             else NCVT = NRU = NCC = 0,
*>                   the algorithm did not converge; D and E contain the
*>                   elements of a bidiagonal matrix which is orthogonally
*>                   similar to the input matrix B;  if INFO = i, i
*>                   elements of E have not converged to zero.
*> \endverbatim
*
*> \par Internal Parameters:
*  =========================
*>
*> \verbatim
*>  TOLMUL  DOUBLE PRECISION, default = max(10,min(100,EPS**(-1/8)))
*>          TOLMUL controls the convergence criterion of the QR loop.
*>          If it is positive, TOLMUL*EPS is the desired relative
*>             precision in the computed singular values.
*>          If it is negative, abs(TOLMUL*EPS*sigma_max) is the
*>             desired absolute accuracy in the computed singular
*>             values (corresponds to relative accuracy
*>             abs(TOLMUL*EPS) in the largest singular value.
*>          abs(TOLMUL) should be between 1 and 1/EPS, and preferably
*>             between 10 (for fast convergence) and .1/EPS
*>             (for there to be some accuracy in the results).
*>          Default is to lose at either one eighth or 2 of the
*>             available decimal digits in each computed singular value
*>             (whichever is smaller).
*>
*>  MAXITR  INTEGER, default = 6
*>          MAXITR controls the maximum number of passes of the
*>          algorithm through its inner loop. The algorithms stops
*>          (and so fails to converge) if the number of passes
*>          through the inner loop exceeds MAXITR*N**2.
*>
*> \endverbatim
*
*> \par Note:
*  ===========
*>
*> \verbatim
*>  Bug report from Cezary Dendek.
*>  On March 23rd 2017, the INTEGER variable MAXIT = MAXITR*N**2 is
*>  removed since it can overflow pretty easily (for N larger or equal
*>  than 18,919). We instead use MAXITDIVN = MAXITR*N.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date June 2017
*
*> \ingroup auxOTHERcomputational
*
*  =====================================================================
      SUBROUTINE DBDSQR( UPLO, N, NCVT, NRU, NCC, D, E, VT, LDVT, U,
     $                   LDU, C, LDC, WORK, INFO )
*
*  -- LAPACK computational routine (version 3.7.1) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     June 2017
*
*     .. Scalar Arguments ..
      CHARACTER          UPLO
      INTEGER            INFO, LDC, LDU, LDVT, N, NCC, NCVT, NRU
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   C( LDC, * ), D( * ), E( * ), U( LDU, * ),
     $                   VT( LDVT, * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ZERO
      PARAMETER          ( ZERO = 0.0D0 )
      DOUBLE PRECISION   ONE
      PARAMETER          ( ONE = 1.0D0 )
      DOUBLE PRECISION   NEGONE
      PARAMETER          ( NEGONE = -1.0D0 )
      DOUBLE PRECISION   HNDRTH
      PARAMETER          ( HNDRTH = 0.01D0 )
      DOUBLE PRECISION   TEN
      PARAMETER          ( TEN = 10.0D0 )
      DOUBLE PRECISION   HNDRD
      PARAMETER          ( HNDRD = 100.0D0 )
      DOUBLE PRECISION   MEIGTH
      PARAMETER          ( MEIGTH = -0.125D0 )
      INTEGER            MAXITR
      PARAMETER          ( MAXITR = 6 )
*     ..
*     .. Local Scalars ..
      LOGICAL            LOWER, ROTATE
      INTEGER            I, IDIR, ISUB, ITER, ITERDIVN, J, LL, LLL, M,
     $                   MAXITDIVN, NM1, NM12, NM13, OLDLL, OLDM
      DOUBLE PRECISION   ABSE, ABSS, COSL, COSR, CS, EPS, F, G, H, MU,
     $                   OLDCS, OLDSN, R, SHIFT, SIGMN, SIGMX, SINL,
     $                   SINR, SLL, SMAX, SMIN, SMINL, SMINOA,
     $                   SN, THRESH, TOL, TOLMUL, UNFL
*     ..
*     .. External Functions ..
      LOGICAL            LSAME
      DOUBLE PRECISION   DLAMCH
      EXTERNAL           LSAME, DLAMCH
*     ..
*     .. External Subroutines ..
      EXTERNAL           DLARTG, DLAS2, DLASQ1, DLASR, DLASV2, DROT,
     $                   DSCAL, DSWAP, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          ABS, DBLE, MAX, MIN, SIGN, SQRT
*     ..
*     .. Executable Statements ..
*
*     Test the input parameters.
*
      INFO = 0
      LOWER = LSAME( UPLO, 'L' )
      IF( .NOT.LSAME( UPLO, 'U' ) .AND. .NOT.LOWER ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( NCVT.LT.0 ) THEN
         INFO = -3
      ELSE IF( NRU.LT.0 ) THEN
         INFO = -4
      ELSE IF( NCC.LT.0 ) THEN
         INFO = -5
      ELSE IF( ( NCVT.EQ.0 .AND. LDVT.LT.1 ) .OR.
     $         ( NCVT.GT.0 .AND. LDVT.LT.MAX( 1, N ) ) ) THEN
         INFO = -9
      ELSE IF( LDU.LT.MAX( 1, NRU ) ) THEN
         INFO = -11
      ELSE IF( ( NCC.EQ.0 .AND. LDC.LT.1 ) .OR.
     $         ( NCC.GT.0 .AND. LDC.LT.MAX( 1, N ) ) ) THEN
         INFO = -13
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DBDSQR', -INFO )
         RETURN
      END IF
      IF( N.EQ.0 )
     $   RETURN
      IF( N.EQ.1 )
     $   GO TO 160
*
*     ROTATE is true if any singular vectors desired, false otherwise
*
      ROTATE = ( NCVT.GT.0 ) .OR. ( NRU.GT.0 ) .OR. ( NCC.GT.0 )
*
*     If no singular vectors desired, use qd algorithm
*
      IF( .NOT.ROTATE ) THEN
         CALL DLASQ1( N, D, E, WORK, INFO )
*
*     If INFO equals 2, dqds didn't finish, try to finish
*
         IF( INFO .NE. 2 ) RETURN
         INFO = 0
      END IF
*
      NM1 = N - 1
      NM12 = NM1 + NM1
      NM13 = NM12 + NM1
      IDIR = 0
*
*     Get machine constants
*
      EPS = DLAMCH( 'Epsilon' )
      UNFL = DLAMCH( 'Safe minimum' )
*
*     If matrix lower bidiagonal, rotate to be upper bidiagonal
*     by applying Givens rotations on the left
*
      IF( LOWER ) THEN
         DO 10 I = 1, N - 1
            CALL DLARTG( D( I ), E( I ), CS, SN, R )
            D( I ) = R
            E( I ) = SN*D( I+1 )
            D( I+1 ) = CS*D( I+1 )
            WORK( I ) = CS
            WORK( NM1+I ) = SN
   10    CONTINUE
*
*        Update singular vectors if desired
*
         IF( NRU.GT.0 )
     $      CALL DLASR( 'R', 'V', 'F', NRU, N, WORK( 1 ), WORK( N ), U,
     $                  LDU )
         IF( NCC.GT.0 )
     $      CALL DLASR( 'L', 'V', 'F', N, NCC, WORK( 1 ), WORK( N ), C,
     $                  LDC )
      END IF
*
*     Compute singular values to relative accuracy TOL
*     (By setting TOL to be negative, algorithm will compute
*     singular values to absolute accuracy ABS(TOL)*norm(input matrix))
*
      TOLMUL = MAX( TEN, MIN( HNDRD, EPS**MEIGTH ) )
      TOL = TOLMUL*EPS
*
*     Compute approximate maximum, minimum singular values
*
      SMAX = ZERO
      DO 20 I = 1, N
         SMAX = MAX( SMAX, ABS( D( I ) ) )
   20 CONTINUE
      DO 30 I = 1, N - 1
         SMAX = MAX( SMAX, ABS( E( I ) ) )
   30 CONTINUE
      SMINL = ZERO
      IF( TOL.GE.ZERO ) THEN
*
*        Relative accuracy desired
*
         SMINOA = ABS( D( 1 ) )
         IF( SMINOA.EQ.ZERO )
     $      GO TO 50
         MU = SMINOA
         DO 40 I = 2, N
            MU = ABS( D( I ) )*( MU / ( MU+ABS( E( I-1 ) ) ) )
            SMINOA = MIN( SMINOA, MU )
            IF( SMINOA.EQ.ZERO )
     $         GO TO 50
   40    CONTINUE
   50    CONTINUE
         SMINOA = SMINOA / SQRT( DBLE( N ) )
         THRESH = MAX( TOL*SMINOA, MAXITR*(N*(N*UNFL)) )
      ELSE
*
*        Absolute accuracy desired
*
         THRESH = MAX( ABS( TOL )*SMAX, MAXITR*(N*(N*UNFL)) )
      END IF
*
*     Prepare for main iteration loop for the singular values
*     (MAXIT is the maximum number of passes through the inner
*     loop permitted before nonconvergence signalled.)
*
      MAXITDIVN = MAXITR*N
      ITERDIVN = 0
      ITER = -1
      OLDLL = -1
      OLDM = -1
*
*     M points to last element of unconverged part of matrix
*
      M = N
*
*     Begin main iteration loop
*
   60 CONTINUE
*
*     Check for convergence or exceeding iteration count
*
      IF( M.LE.1 )
     $   GO TO 160
*
      IF( ITER.GE.N ) THEN
         ITER = ITER - N
         ITERDIVN = ITERDIVN + 1
         IF( ITERDIVN.GE.MAXITDIVN )
     $      GO TO 200
      END IF
*
*     Find diagonal block of matrix to work on
*
      IF( TOL.LT.ZERO .AND. ABS( D( M ) ).LE.THRESH )
     $   D( M ) = ZERO
      SMAX = ABS( D( M ) )
      SMIN = SMAX
      DO 70 LLL = 1, M - 1
         LL = M - LLL
         ABSS = ABS( D( LL ) )
         ABSE = ABS( E( LL ) )
         IF( TOL.LT.ZERO .AND. ABSS.LE.THRESH )
     $      D( LL ) = ZERO
         IF( ABSE.LE.THRESH )
     $      GO TO 80
         SMIN = MIN( SMIN, ABSS )
         SMAX = MAX( SMAX, ABSS, ABSE )
   70 CONTINUE
      LL = 0
      GO TO 90
   80 CONTINUE
      E( LL ) = ZERO
*
*     Matrix splits since E(LL) = 0
*
      IF( LL.EQ.M-1 ) THEN
*
*        Convergence of bottom singular value, return to top of loop
*
         M = M - 1
         GO TO 60
      END IF
   90 CONTINUE
      LL = LL + 1
*
*     E(LL) through E(M-1) are nonzero, E(LL-1) is zero
*
      IF( LL.EQ.M-1 ) THEN
*
*        2 by 2 block, handle separately
*
         CALL DLASV2( D( M-1 ), E( M-1 ), D( M ), SIGMN, SIGMX, SINR,
     $                COSR, SINL, COSL )
         D( M-1 ) = SIGMX
         E( M-1 ) = ZERO
         D( M ) = SIGMN
*
*        Compute singular vectors, if desired
*
         IF( NCVT.GT.0 )
     $      CALL DROT( NCVT, VT( M-1, 1 ), LDVT, VT( M, 1 ), LDVT, COSR,
     $                 SINR )
         IF( NRU.GT.0 )
     $      CALL DROT( NRU, U( 1, M-1 ), 1, U( 1, M ), 1, COSL, SINL )
         IF( NCC.GT.0 )
     $      CALL DROT( NCC, C( M-1, 1 ), LDC, C( M, 1 ), LDC, COSL,
     $                 SINL )
         M = M - 2
         GO TO 60
      END IF
*
*     If working on new submatrix, choose shift direction
*     (from larger end diagonal element towards smaller)
*
      IF( LL.GT.OLDM .OR. M.LT.OLDLL ) THEN
         IF( ABS( D( LL ) ).GE.ABS( D( M ) ) ) THEN
*
*           Chase bulge from top (big end) to bottom (small end)
*
            IDIR = 1
         ELSE
*
*           Chase bulge from bottom (big end) to top (small end)
*
            IDIR = 2
         END IF
      END IF
*
*     Apply convergence tests
*
      IF( IDIR.EQ.1 ) THEN
*
*        Run convergence test in forward direction
*        First apply standard test to bottom of matrix
*
         IF( ABS( E( M-1 ) ).LE.ABS( TOL )*ABS( D( M ) ) .OR.
     $       ( TOL.LT.ZERO .AND. ABS( E( M-1 ) ).LE.THRESH ) ) THEN
            E( M-1 ) = ZERO
            GO TO 60
         END IF
*
         IF( TOL.GE.ZERO ) THEN
*
*           If relative accuracy desired,
*           apply convergence criterion forward
*
            MU = ABS( D( LL ) )
            SMINL = MU
            DO 100 LLL = LL, M - 1
               IF( ABS( E( LLL ) ).LE.TOL*MU ) THEN
                  E( LLL ) = ZERO
                  GO TO 60
               END IF
               MU = ABS( D( LLL+1 ) )*( MU / ( MU+ABS( E( LLL ) ) ) )
               SMINL = MIN( SMINL, MU )
  100       CONTINUE
         END IF
*
      ELSE
*
*        Run convergence test in backward direction
*        First apply standard test to top of matrix
*
         IF( ABS( E( LL ) ).LE.ABS( TOL )*ABS( D( LL ) ) .OR.
     $       ( TOL.LT.ZERO .AND. ABS( E( LL ) ).LE.THRESH ) ) THEN
            E( LL ) = ZERO
            GO TO 60
         END IF
*
         IF( TOL.GE.ZERO ) THEN
*
*           If relative accuracy desired,
*           apply convergence criterion backward
*
            MU = ABS( D( M ) )
            SMINL = MU
            DO 110 LLL = M - 1, LL, -1
               IF( ABS( E( LLL ) ).LE.TOL*MU ) THEN
                  E( LLL ) = ZERO
                  GO TO 60
               END IF
               MU = ABS( D( LLL ) )*( MU / ( MU+ABS( E( LLL ) ) ) )
               SMINL = MIN( SMINL, MU )
  110       CONTINUE
         END IF
      END IF
      OLDLL = LL
      OLDM = M
*
*     Compute shift.  First, test if shifting would ruin relative
*     accuracy, and if so set the shift to zero.
*
      IF( TOL.GE.ZERO .AND. N*TOL*( SMINL / SMAX ).LE.
     $    MAX( EPS, HNDRTH*TOL ) ) THEN
*
*        Use a zero shift to avoid loss of relative accuracy
*
         SHIFT = ZERO
      ELSE
*
*        Compute the shift from 2-by-2 block at end of matrix
*
         IF( IDIR.EQ.1 ) THEN
            SLL = ABS( D( LL ) )
            CALL DLAS2( D( M-1 ), E( M-1 ), D( M ), SHIFT, R )
         ELSE
            SLL = ABS( D( M ) )
            CALL DLAS2( D( LL ), E( LL ), D( LL+1 ), SHIFT, R )
         END IF
*
*        Test if shift negligible, and if so set to zero
*
         IF( SLL.GT.ZERO ) THEN
            IF( ( SHIFT / SLL )**2.LT.EPS )
     $         SHIFT = ZERO
         END IF
      END IF
*
*     Increment iteration count
*
      ITER = ITER + M - LL
*
*     If SHIFT = 0, do simplified QR iteration
*
      IF( SHIFT.EQ.ZERO ) THEN
         IF( IDIR.EQ.1 ) THEN
*
*           Chase bulge from top to bottom
*           Save cosines and sines for later singular vector updates
*
            CS = ONE
            OLDCS = ONE
            DO 120 I = LL, M - 1
               CALL DLARTG( D( I )*CS, E( I ), CS, SN, R )
               IF( I.GT.LL )
     $            E( I-1 ) = OLDSN*R
               CALL DLARTG( OLDCS*R, D( I+1 )*SN, OLDCS, OLDSN, D( I ) )
               WORK( I-LL+1 ) = CS
               WORK( I-LL+1+NM1 ) = SN
               WORK( I-LL+1+NM12 ) = OLDCS
               WORK( I-LL+1+NM13 ) = OLDSN
  120       CONTINUE
            H = D( M )*CS
            D( M ) = H*OLDCS
            E( M-1 ) = H*OLDSN
*
*           Update singular vectors
*
            IF( NCVT.GT.0 )
     $         CALL DLASR( 'L', 'V', 'F', M-LL+1, NCVT, WORK( 1 ),
     $                     WORK( N ), VT( LL, 1 ), LDVT )
            IF( NRU.GT.0 )
     $         CALL DLASR( 'R', 'V', 'F', NRU, M-LL+1, WORK( NM12+1 ),
     $                     WORK( NM13+1 ), U( 1, LL ), LDU )
            IF( NCC.GT.0 )
     $         CALL DLASR( 'L', 'V', 'F', M-LL+1, NCC, WORK( NM12+1 ),
     $                     WORK( NM13+1 ), C( LL, 1 ), LDC )
*
*           Test convergence
*
            IF( ABS( E( M-1 ) ).LE.THRESH )
     $         E( M-1 ) = ZERO
*
         ELSE
*
*           Chase bulge from bottom to top
*           Save cosines and sines for later singular vector updates
*
            CS = ONE
            OLDCS = ONE
            DO 130 I = M, LL + 1, -1
               CALL DLARTG( D( I )*CS, E( I-1 ), CS, SN, R )
               IF( I.LT.M )
     $            E( I ) = OLDSN*R
               CALL DLARTG( OLDCS*R, D( I-1 )*SN, OLDCS, OLDSN, D( I ) )
               WORK( I-LL ) = CS
               WORK( I-LL+NM1 ) = -SN
               WORK( I-LL+NM12 ) = OLDCS
               WORK( I-LL+NM13 ) = -OLDSN
  130       CONTINUE
            H = D( LL )*CS
            D( LL ) = H*OLDCS
            E( LL ) = H*OLDSN
*
*           Update singular vectors
*
            IF( NCVT.GT.0 )
     $         CALL DLASR( 'L', 'V', 'B', M-LL+1, NCVT, WORK( NM12+1 ),
     $                     WORK( NM13+1 ), VT( LL, 1 ), LDVT )
            IF( NRU.GT.0 )
     $         CALL DLASR( 'R', 'V', 'B', NRU, M-LL+1, WORK( 1 ),
     $                     WORK( N ), U( 1, LL ), LDU )
            IF( NCC.GT.0 )
     $         CALL DLASR( 'L', 'V', 'B', M-LL+1, NCC, WORK( 1 ),
     $                     WORK( N ), C( LL, 1 ), LDC )
*
*           Test convergence
*
            IF( ABS( E( LL ) ).LE.THRESH )
     $         E( LL ) = ZERO
         END IF
      ELSE
*
*        Use nonzero shift
*
         IF( IDIR.EQ.1 ) THEN
*
*           Chase bulge from top to bottom
*           Save cosines and sines for later singular vector updates
*
            F = ( ABS( D( LL ) )-SHIFT )*
     $          ( SIGN( ONE, D( LL ) )+SHIFT / D( LL ) )
            G = E( LL )
            DO 140 I = LL, M - 1
               CALL DLARTG( F, G, COSR, SINR, R )
               IF( I.GT.LL )
     $            E( I-1 ) = R
               F = COSR*D( I ) + SINR*E( I )
               E( I ) = COSR*E( I ) - SINR*D( I )
               G = SINR*D( I+1 )
               D( I+1 ) = COSR*D( I+1 )
               CALL DLARTG( F, G, COSL, SINL, R )
               D( I ) = R
               F = COSL*E( I ) + SINL*D( I+1 )
               D( I+1 ) = COSL*D( I+1 ) - SINL*E( I )
               IF( I.LT.M-1 ) THEN
                  G = SINL*E( I+1 )
                  E( I+1 ) = COSL*E( I+1 )
               END IF
               WORK( I-LL+1 ) = COSR
               WORK( I-LL+1+NM1 ) = SINR
               WORK( I-LL+1+NM12 ) = COSL
               WORK( I-LL+1+NM13 ) = SINL
  140       CONTINUE
            E( M-1 ) = F
*
*           Update singular vectors
*
            IF( NCVT.GT.0 )
     $         CALL DLASR( 'L', 'V', 'F', M-LL+1, NCVT, WORK( 1 ),
     $                     WORK( N ), VT( LL, 1 ), LDVT )
            IF( NRU.GT.0 )
     $         CALL DLASR( 'R', 'V', 'F', NRU, M-LL+1, WORK( NM12+1 ),
     $                     WORK( NM13+1 ), U( 1, LL ), LDU )
            IF( NCC.GT.0 )
     $         CALL DLASR( 'L', 'V', 'F', M-LL+1, NCC, WORK( NM12+1 ),
     $                     WORK( NM13+1 ), C( LL, 1 ), LDC )
*
*           Test convergence
*
            IF( ABS( E( M-1 ) ).LE.THRESH )
     $         E( M-1 ) = ZERO
*
         ELSE
*
*           Chase bulge from bottom to top
*           Save cosines and sines for later singular vector updates
*
            F = ( ABS( D( M ) )-SHIFT )*( SIGN( ONE, D( M ) )+SHIFT /
     $          D( M ) )
            G = E( M-1 )
            DO 150 I = M, LL + 1, -1
               CALL DLARTG( F, G, COSR, SINR, R )
               IF( I.LT.M )
     $            E( I ) = R
               F = COSR*D( I ) + SINR*E( I-1 )
               E( I-1 ) = COSR*E( I-1 ) - SINR*D( I )
               G = SINR*D( I-1 )
               D( I-1 ) = COSR*D( I-1 )
               CALL DLARTG( F, G, COSL, SINL, R )
               D( I ) = R
               F = COSL*E( I-1 ) + SINL*D( I-1 )
               D( I-1 ) = COSL*D( I-1 ) - SINL*E( I-1 )
               IF( I.GT.LL+1 ) THEN
                  G = SINL*E( I-2 )
                  E( I-2 ) = COSL*E( I-2 )
               END IF
               WORK( I-LL ) = COSR
               WORK( I-LL+NM1 ) = -SINR
               WORK( I-LL+NM12 ) = COSL
               WORK( I-LL+NM13 ) = -SINL
  150       CONTINUE
            E( LL ) = F
*
*           Test convergence
*
            IF( ABS( E( LL ) ).LE.THRESH )
     $         E( LL ) = ZERO
*
*           Update singular vectors if desired
*
            IF( NCVT.GT.0 )
     $         CALL DLASR( 'L', 'V', 'B', M-LL+1, NCVT, WORK( NM12+1 ),
     $                     WORK( NM13+1 ), VT( LL, 1 ), LDVT )
            IF( NRU.GT.0 )
     $         CALL DLASR( 'R', 'V', 'B', NRU, M-LL+1, WORK( 1 ),
     $                     WORK( N ), U( 1, LL ), LDU )
            IF( NCC.GT.0 )
     $         CALL DLASR( 'L', 'V', 'B', M-LL+1, NCC, WORK( 1 ),
     $                     WORK( N ), C( LL, 1 ), LDC )
         END IF
      END IF
*
*     QR iteration finished, go back and check convergence
*
      GO TO 60
*
*     All singular values converged, so make them positive
*
  160 CONTINUE
      DO 170 I = 1, N
         IF( D( I ).LT.ZERO ) THEN
            D( I ) = -D( I )
*
*           Change sign of singular vectors, if desired
*
            IF( NCVT.GT.0 )
     $         CALL DSCAL( NCVT, NEGONE, VT( I, 1 ), LDVT )
         END IF
  170 CONTINUE
*
*     Sort the singular values into decreasing order (insertion sort on
*     singular values, but only one transposition per singular vector)
*
      DO 190 I = 1, N - 1
*
*        Scan for smallest D(I)
*
         ISUB = 1
         SMIN = D( 1 )
         DO 180 J = 2, N + 1 - I
            IF( D( J ).LE.SMIN ) THEN
               ISUB = J
               SMIN = D( J )
            END IF
  180    CONTINUE
         IF( ISUB.NE.N+1-I ) THEN
*
*           Swap singular values and vectors
*
            D( ISUB ) = D( N+1-I )
            D( N+1-I ) = SMIN
            IF( NCVT.GT.0 )
     $         CALL DSWAP( NCVT, VT( ISUB, 1 ), LDVT, VT( N+1-I, 1 ),
     $                     LDVT )
            IF( NRU.GT.0 )
     $         CALL DSWAP( NRU, U( 1, ISUB ), 1, U( 1, N+1-I ), 1 )
            IF( NCC.GT.0 )
     $         CALL DSWAP( NCC, C( ISUB, 1 ), LDC, C( N+1-I, 1 ), LDC )
         END IF
  190 CONTINUE
      GO TO 220
*
*     Maximum number of iterations exceeded, failure to converge
*
  200 CONTINUE
      INFO = 0
      DO 210 I = 1, N - 1
         IF( E( I ).NE.ZERO )
     $      INFO = INFO + 1
  210 CONTINUE
  220 CONTINUE
      RETURN
*
*     End of DBDSQR
*
      END
*> \brief \b DDISNA
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DDISNA + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/ddisna.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/ddisna.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/ddisna.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DDISNA( JOB, M, N, D, SEP, INFO )
*
*       .. Scalar Arguments ..
*       CHARACTER          JOB
*       INTEGER            INFO, M, N
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   D( * ), SEP( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DDISNA computes the reciprocal condition numbers for the eigenvectors
*> of a real symmetric or complex Hermitian matrix or for the left or
*> right singular vectors of a general m-by-n matrix. The reciprocal
*> condition number is the 'gap' between the corresponding eigenvalue or
*> singular value and the nearest other one.
*>
*> The bound on the error, measured by angle in radians, in the I-th
*> computed vector is given by
*>
*>        DLAMCH( 'E' ) * ( ANORM / SEP( I ) )
*>
*> where ANORM = 2-norm(A) = max( abs( D(j) ) ).  SEP(I) is not allowed
*> to be smaller than DLAMCH( 'E' )*ANORM in order to limit the size of
*> the error bound.
*>
*> DDISNA may also be used to compute error bounds for eigenvectors of
*> the generalized symmetric definite eigenproblem.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] JOB
*> \verbatim
*>          JOB is CHARACTER*1
*>          Specifies for which problem the reciprocal condition numbers
*>          should be computed:
*>          = 'E':  the eigenvectors of a symmetric/Hermitian matrix;
*>          = 'L':  the left singular vectors of a general matrix;
*>          = 'R':  the right singular vectors of a general matrix.
*> \endverbatim
*>
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix. M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          If JOB = 'L' or 'R', the number of columns of the matrix,
*>          in which case N >= 0. Ignored if JOB = 'E'.
*> \endverbatim
*>
*> \param[in] D
*> \verbatim
*>          D is DOUBLE PRECISION array, dimension (M) if JOB = 'E'
*>                              dimension (min(M,N)) if JOB = 'L' or 'R'
*>          The eigenvalues (if JOB = 'E') or singular values (if JOB =
*>          'L' or 'R') of the matrix, in either increasing or decreasing
*>          order. If singular values, they must be non-negative.
*> \endverbatim
*>
*> \param[out] SEP
*> \verbatim
*>          SEP is DOUBLE PRECISION array, dimension (M) if JOB = 'E'
*>                               dimension (min(M,N)) if JOB = 'L' or 'R'
*>          The reciprocal condition numbers of the vectors.
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit.
*>          < 0:  if INFO = -i, the i-th argument had an illegal value.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup auxOTHERcomputational
*
*  =====================================================================
      SUBROUTINE DDISNA( JOB, M, N, D, SEP, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      CHARACTER          JOB
      INTEGER            INFO, M, N
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   D( * ), SEP( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ZERO
      PARAMETER          ( ZERO = 0.0D+0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            DECR, EIGEN, INCR, LEFT, RIGHT, SING
      INTEGER            I, K
      DOUBLE PRECISION   ANORM, EPS, NEWGAP, OLDGAP, SAFMIN, THRESH
*     ..
*     .. External Functions ..
      LOGICAL            LSAME
      DOUBLE PRECISION   DLAMCH
      EXTERNAL           LSAME, DLAMCH
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          ABS, MAX, MIN
*     ..
*     .. External Subroutines ..
      EXTERNAL           XERBLA
*     ..
*     .. Executable Statements ..
*
*     Test the input arguments
*
      INFO = 0
      EIGEN = LSAME( JOB, 'E' )
      LEFT = LSAME( JOB, 'L' )
      RIGHT = LSAME( JOB, 'R' )
      SING = LEFT .OR. RIGHT
      IF( EIGEN ) THEN
         K = M
      ELSE IF( SING ) THEN
         K = MIN( M, N )
      END IF
      IF( .NOT.EIGEN .AND. .NOT.SING ) THEN
         INFO = -1
      ELSE IF( M.LT.0 ) THEN
         INFO = -2
      ELSE IF( K.LT.0 ) THEN
         INFO = -3
      ELSE
         INCR = .TRUE.
         DECR = .TRUE.
         DO 10 I = 1, K - 1
            IF( INCR )
     $         INCR = INCR .AND. D( I ).LE.D( I+1 )
            IF( DECR )
     $         DECR = DECR .AND. D( I ).GE.D( I+1 )
   10    CONTINUE
         IF( SING .AND. K.GT.0 ) THEN
            IF( INCR )
     $         INCR = INCR .AND. ZERO.LE.D( 1 )
            IF( DECR )
     $         DECR = DECR .AND. D( K ).GE.ZERO
         END IF
         IF( .NOT.( INCR .OR. DECR ) )
     $      INFO = -4
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DDISNA', -INFO )
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( K.EQ.0 )
     $   RETURN
*
*     Compute reciprocal condition numbers
*
      IF( K.EQ.1 ) THEN
         SEP( 1 ) = DLAMCH( 'O' )
      ELSE
         OLDGAP = ABS( D( 2 )-D( 1 ) )
         SEP( 1 ) = OLDGAP
         DO 20 I = 2, K - 1
            NEWGAP = ABS( D( I+1 )-D( I ) )
            SEP( I ) = MIN( OLDGAP, NEWGAP )
            OLDGAP = NEWGAP
   20    CONTINUE
         SEP( K ) = OLDGAP
      END IF
      IF( SING ) THEN
         IF( ( LEFT .AND. M.GT.N ) .OR. ( RIGHT .AND. M.LT.N ) ) THEN
            IF( INCR )
     $         SEP( 1 ) = MIN( SEP( 1 ), D( 1 ) )
            IF( DECR )
     $         SEP( K ) = MIN( SEP( K ), D( K ) )
         END IF
      END IF
*
*     Ensure that reciprocal condition numbers are not less than
*     threshold, in order to limit the size of the error bound
*
      EPS = DLAMCH( 'E' )
      SAFMIN = DLAMCH( 'S' )
      ANORM = MAX( ABS( D( 1 ) ), ABS( D( K ) ) )
      IF( ANORM.EQ.ZERO ) THEN
         THRESH = EPS
      ELSE
         THRESH = MAX( EPS*ANORM, SAFMIN )
      END IF
      DO 30 I = 1, K
         SEP( I ) = MAX( SEP( I ), THRESH )
   30 CONTINUE
*
      RETURN
*
*     End of DDISNA
*
      END
*> \brief \b DGBBRD
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGBBRD + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgbbrd.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgbbrd.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgbbrd.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGBBRD( VECT, M, N, NCC, KL, KU, AB, LDAB, D, E, Q,
*                          LDQ, PT, LDPT, C, LDC, WORK, INFO )
*
*       .. Scalar Arguments ..
*       CHARACTER          VECT
*       INTEGER            INFO, KL, KU, LDAB, LDC, LDPT, LDQ, M, N, NCC
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   AB( LDAB, * ), C( LDC, * ), D( * ), E( * ),
*      $                   PT( LDPT, * ), Q( LDQ, * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGBBRD reduces a real general m-by-n band matrix A to upper
*> bidiagonal form B by an orthogonal transformation: Q**T * A * P = B.
*>
*> The routine computes B, and optionally forms Q or P**T, or computes
*> Q**T*C for a given matrix C.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] VECT
*> \verbatim
*>          VECT is CHARACTER*1
*>          Specifies whether or not the matrices Q and P**T are to be
*>          formed.
*>          = 'N': do not form Q or P**T;
*>          = 'Q': form Q only;
*>          = 'P': form P**T only;
*>          = 'B': form both.
*> \endverbatim
*>
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A.  M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in] NCC
*> \verbatim
*>          NCC is INTEGER
*>          The number of columns of the matrix C.  NCC >= 0.
*> \endverbatim
*>
*> \param[in] KL
*> \verbatim
*>          KL is INTEGER
*>          The number of subdiagonals of the matrix A. KL >= 0.
*> \endverbatim
*>
*> \param[in] KU
*> \verbatim
*>          KU is INTEGER
*>          The number of superdiagonals of the matrix A. KU >= 0.
*> \endverbatim
*>
*> \param[in,out] AB
*> \verbatim
*>          AB is DOUBLE PRECISION array, dimension (LDAB,N)
*>          On entry, the m-by-n band matrix A, stored in rows 1 to
*>          KL+KU+1. The j-th column of A is stored in the j-th column of
*>          the array AB as follows:
*>          AB(ku+1+i-j,j) = A(i,j) for max(1,j-ku)<=i<=min(m,j+kl).
*>          On exit, A is overwritten by values generated during the
*>          reduction.
*> \endverbatim
*>
*> \param[in] LDAB
*> \verbatim
*>          LDAB is INTEGER
*>          The leading dimension of the array A. LDAB >= KL+KU+1.
*> \endverbatim
*>
*> \param[out] D
*> \verbatim
*>          D is DOUBLE PRECISION array, dimension (min(M,N))
*>          The diagonal elements of the bidiagonal matrix B.
*> \endverbatim
*>
*> \param[out] E
*> \verbatim
*>          E is DOUBLE PRECISION array, dimension (min(M,N)-1)
*>          The superdiagonal elements of the bidiagonal matrix B.
*> \endverbatim
*>
*> \param[out] Q
*> \verbatim
*>          Q is DOUBLE PRECISION array, dimension (LDQ,M)
*>          If VECT = 'Q' or 'B', the m-by-m orthogonal matrix Q.
*>          If VECT = 'N' or 'P', the array Q is not referenced.
*> \endverbatim
*>
*> \param[in] LDQ
*> \verbatim
*>          LDQ is INTEGER
*>          The leading dimension of the array Q.
*>          LDQ >= max(1,M) if VECT = 'Q' or 'B'; LDQ >= 1 otherwise.
*> \endverbatim
*>
*> \param[out] PT
*> \verbatim
*>          PT is DOUBLE PRECISION array, dimension (LDPT,N)
*>          If VECT = 'P' or 'B', the n-by-n orthogonal matrix P'.
*>          If VECT = 'N' or 'Q', the array PT is not referenced.
*> \endverbatim
*>
*> \param[in] LDPT
*> \verbatim
*>          LDPT is INTEGER
*>          The leading dimension of the array PT.
*>          LDPT >= max(1,N) if VECT = 'P' or 'B'; LDPT >= 1 otherwise.
*> \endverbatim
*>
*> \param[in,out] C
*> \verbatim
*>          C is DOUBLE PRECISION array, dimension (LDC,NCC)
*>          On entry, an m-by-ncc matrix C.
*>          On exit, C is overwritten by Q**T*C.
*>          C is not referenced if NCC = 0.
*> \endverbatim
*>
*> \param[in] LDC
*> \verbatim
*>          LDC is INTEGER
*>          The leading dimension of the array C.
*>          LDC >= max(1,M) if NCC > 0; LDC >= 1 if NCC = 0.
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (2*max(M,N))
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit.
*>          < 0:  if INFO = -i, the i-th argument had an illegal value.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGBcomputational
*
*  =====================================================================
      SUBROUTINE DGBBRD( VECT, M, N, NCC, KL, KU, AB, LDAB, D, E, Q,
     $                   LDQ, PT, LDPT, C, LDC, WORK, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      CHARACTER          VECT
      INTEGER            INFO, KL, KU, LDAB, LDC, LDPT, LDQ, M, N, NCC
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   AB( LDAB, * ), C( LDC, * ), D( * ), E( * ),
     $                   PT( LDPT, * ), Q( LDQ, * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ZERO, ONE
      PARAMETER          ( ZERO = 0.0D+0, ONE = 1.0D+0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            WANTB, WANTC, WANTPT, WANTQ
      INTEGER            I, INCA, J, J1, J2, KB, KB1, KK, KLM, KLU1,
     $                   KUN, L, MINMN, ML, ML0, MN, MU, MU0, NR, NRT
      DOUBLE PRECISION   RA, RB, RC, RS
*     ..
*     .. External Subroutines ..
      EXTERNAL           DLARGV, DLARTG, DLARTV, DLASET, DROT, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, MIN
*     ..
*     .. External Functions ..
      LOGICAL            LSAME
      EXTERNAL           LSAME
*     ..
*     .. Executable Statements ..
*
*     Test the input parameters
*
      WANTB = LSAME( VECT, 'B' )
      WANTQ = LSAME( VECT, 'Q' ) .OR. WANTB
      WANTPT = LSAME( VECT, 'P' ) .OR. WANTB
      WANTC = NCC.GT.0
      KLU1 = KL + KU + 1
      INFO = 0
      IF( .NOT.WANTQ .AND. .NOT.WANTPT .AND. .NOT.LSAME( VECT, 'N' ) )
     $     THEN
         INFO = -1
      ELSE IF( M.LT.0 ) THEN
         INFO = -2
      ELSE IF( N.LT.0 ) THEN
         INFO = -3
      ELSE IF( NCC.LT.0 ) THEN
         INFO = -4
      ELSE IF( KL.LT.0 ) THEN
         INFO = -5
      ELSE IF( KU.LT.0 ) THEN
         INFO = -6
      ELSE IF( LDAB.LT.KLU1 ) THEN
         INFO = -8
      ELSE IF( LDQ.LT.1 .OR. WANTQ .AND. LDQ.LT.MAX( 1, M ) ) THEN
         INFO = -12
      ELSE IF( LDPT.LT.1 .OR. WANTPT .AND. LDPT.LT.MAX( 1, N ) ) THEN
         INFO = -14
      ELSE IF( LDC.LT.1 .OR. WANTC .AND. LDC.LT.MAX( 1, M ) ) THEN
         INFO = -16
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGBBRD', -INFO )
         RETURN
      END IF
*
*     Initialize Q and P**T to the unit matrix, if needed
*
      IF( WANTQ )
     $   CALL DLASET( 'Full', M, M, ZERO, ONE, Q, LDQ )
      IF( WANTPT )
     $   CALL DLASET( 'Full', N, N, ZERO, ONE, PT, LDPT )
*
*     Quick return if possible.
*
      IF( M.EQ.0 .OR. N.EQ.0 )
     $   RETURN
*
      MINMN = MIN( M, N )
*
      IF( KL+KU.GT.1 ) THEN
*
*        Reduce to upper bidiagonal form if KU > 0; if KU = 0, reduce
*        first to lower bidiagonal form and then transform to upper
*        bidiagonal
*
         IF( KU.GT.0 ) THEN
            ML0 = 1
            MU0 = 2
         ELSE
            ML0 = 2
            MU0 = 1
         END IF
*
*        Wherever possible, plane rotations are generated and applied in
*        vector operations of length NR over the index set J1:J2:KLU1.
*
*        The sines of the plane rotations are stored in WORK(1:max(m,n))
*        and the cosines in WORK(max(m,n)+1:2*max(m,n)).
*
         MN = MAX( M, N )
         KLM = MIN( M-1, KL )
         KUN = MIN( N-1, KU )
         KB = KLM + KUN
         KB1 = KB + 1
         INCA = KB1*LDAB
         NR = 0
         J1 = KLM + 2
         J2 = 1 - KUN
*
         DO 90 I = 1, MINMN
*
*           Reduce i-th column and i-th row of matrix to bidiagonal form
*
            ML = KLM + 1
            MU = KUN + 1
            DO 80 KK = 1, KB
               J1 = J1 + KB
               J2 = J2 + KB
*
*              generate plane rotations to annihilate nonzero elements
*              which have been created below the band
*
               IF( NR.GT.0 )
     $            CALL DLARGV( NR, AB( KLU1, J1-KLM-1 ), INCA,
     $                         WORK( J1 ), KB1, WORK( MN+J1 ), KB1 )
*
*              apply plane rotations from the left
*
               DO 10 L = 1, KB
                  IF( J2-KLM+L-1.GT.N ) THEN
                     NRT = NR - 1
                  ELSE
                     NRT = NR
                  END IF
                  IF( NRT.GT.0 )
     $               CALL DLARTV( NRT, AB( KLU1-L, J1-KLM+L-1 ), INCA,
     $                            AB( KLU1-L+1, J1-KLM+L-1 ), INCA,
     $                            WORK( MN+J1 ), WORK( J1 ), KB1 )
   10          CONTINUE
*
               IF( ML.GT.ML0 ) THEN
                  IF( ML.LE.M-I+1 ) THEN
*
*                    generate plane rotation to annihilate a(i+ml-1,i)
*                    within the band, and apply rotation from the left
*
                     CALL DLARTG( AB( KU+ML-1, I ), AB( KU+ML, I ),
     $                            WORK( MN+I+ML-1 ), WORK( I+ML-1 ),
     $                            RA )
                     AB( KU+ML-1, I ) = RA
                     IF( I.LT.N )
     $                  CALL DROT( MIN( KU+ML-2, N-I ),
     $                             AB( KU+ML-2, I+1 ), LDAB-1,
     $                             AB( KU+ML-1, I+1 ), LDAB-1,
     $                             WORK( MN+I+ML-1 ), WORK( I+ML-1 ) )
                  END IF
                  NR = NR + 1
                  J1 = J1 - KB1
               END IF
*
               IF( WANTQ ) THEN
*
*                 accumulate product of plane rotations in Q
*
                  DO 20 J = J1, J2, KB1
                     CALL DROT( M, Q( 1, J-1 ), 1, Q( 1, J ), 1,
     $                          WORK( MN+J ), WORK( J ) )
   20             CONTINUE
               END IF
*
               IF( WANTC ) THEN
*
*                 apply plane rotations to C
*
                  DO 30 J = J1, J2, KB1
                     CALL DROT( NCC, C( J-1, 1 ), LDC, C( J, 1 ), LDC,
     $                          WORK( MN+J ), WORK( J ) )
   30             CONTINUE
               END IF
*
               IF( J2+KUN.GT.N ) THEN
*
*                 adjust J2 to keep within the bounds of the matrix
*
                  NR = NR - 1
                  J2 = J2 - KB1
               END IF
*
               DO 40 J = J1, J2, KB1
*
*                 create nonzero element a(j-1,j+ku) above the band
*                 and store it in WORK(n+1:2*n)
*
                  WORK( J+KUN ) = WORK( J )*AB( 1, J+KUN )
                  AB( 1, J+KUN ) = WORK( MN+J )*AB( 1, J+KUN )
   40          CONTINUE
*
*              generate plane rotations to annihilate nonzero elements
*              which have been generated above the band
*
               IF( NR.GT.0 )
     $            CALL DLARGV( NR, AB( 1, J1+KUN-1 ), INCA,
     $                         WORK( J1+KUN ), KB1, WORK( MN+J1+KUN ),
     $                         KB1 )
*
*              apply plane rotations from the right
*
               DO 50 L = 1, KB
                  IF( J2+L-1.GT.M ) THEN
                     NRT = NR - 1
                  ELSE
                     NRT = NR
                  END IF
                  IF( NRT.GT.0 )
     $               CALL DLARTV( NRT, AB( L+1, J1+KUN-1 ), INCA,
     $                            AB( L, J1+KUN ), INCA,
     $                            WORK( MN+J1+KUN ), WORK( J1+KUN ),
     $                            KB1 )
   50          CONTINUE
*
               IF( ML.EQ.ML0 .AND. MU.GT.MU0 ) THEN
                  IF( MU.LE.N-I+1 ) THEN
*
*                    generate plane rotation to annihilate a(i,i+mu-1)
*                    within the band, and apply rotation from the right
*
                     CALL DLARTG( AB( KU-MU+3, I+MU-2 ),
     $                            AB( KU-MU+2, I+MU-1 ),
     $                            WORK( MN+I+MU-1 ), WORK( I+MU-1 ),
     $                            RA )
                     AB( KU-MU+3, I+MU-2 ) = RA
                     CALL DROT( MIN( KL+MU-2, M-I ),
     $                          AB( KU-MU+4, I+MU-2 ), 1,
     $                          AB( KU-MU+3, I+MU-1 ), 1,
     $                          WORK( MN+I+MU-1 ), WORK( I+MU-1 ) )
                  END IF
                  NR = NR + 1
                  J1 = J1 - KB1
               END IF
*
               IF( WANTPT ) THEN
*
*                 accumulate product of plane rotations in P**T
*
                  DO 60 J = J1, J2, KB1
                     CALL DROT( N, PT( J+KUN-1, 1 ), LDPT,
     $                          PT( J+KUN, 1 ), LDPT, WORK( MN+J+KUN ),
     $                          WORK( J+KUN ) )
   60             CONTINUE
               END IF
*
               IF( J2+KB.GT.M ) THEN
*
*                 adjust J2 to keep within the bounds of the matrix
*
                  NR = NR - 1
                  J2 = J2 - KB1
               END IF
*
               DO 70 J = J1, J2, KB1
*
*                 create nonzero element a(j+kl+ku,j+ku-1) below the
*                 band and store it in WORK(1:n)
*
                  WORK( J+KB ) = WORK( J+KUN )*AB( KLU1, J+KUN )
                  AB( KLU1, J+KUN ) = WORK( MN+J+KUN )*AB( KLU1, J+KUN )
   70          CONTINUE
*
               IF( ML.GT.ML0 ) THEN
                  ML = ML - 1
               ELSE
                  MU = MU - 1
               END IF
   80       CONTINUE
   90    CONTINUE
      END IF
*
      IF( KU.EQ.0 .AND. KL.GT.0 ) THEN
*
*        A has been reduced to lower bidiagonal form
*
*        Transform lower bidiagonal form to upper bidiagonal by applying
*        plane rotations from the left, storing diagonal elements in D
*        and off-diagonal elements in E
*
         DO 100 I = 1, MIN( M-1, N )
            CALL DLARTG( AB( 1, I ), AB( 2, I ), RC, RS, RA )
            D( I ) = RA
            IF( I.LT.N ) THEN
               E( I ) = RS*AB( 1, I+1 )
               AB( 1, I+1 ) = RC*AB( 1, I+1 )
            END IF
            IF( WANTQ )
     $         CALL DROT( M, Q( 1, I ), 1, Q( 1, I+1 ), 1, RC, RS )
            IF( WANTC )
     $         CALL DROT( NCC, C( I, 1 ), LDC, C( I+1, 1 ), LDC, RC,
     $                    RS )
  100    CONTINUE
         IF( M.LE.N )
     $      D( M ) = AB( 1, M )
      ELSE IF( KU.GT.0 ) THEN
*
*        A has been reduced to upper bidiagonal form
*
         IF( M.LT.N ) THEN
*
*           Annihilate a(m,m+1) by applying plane rotations from the
*           right, storing diagonal elements in D and off-diagonal
*           elements in E
*
            RB = AB( KU, M+1 )
            DO 110 I = M, 1, -1
               CALL DLARTG( AB( KU+1, I ), RB, RC, RS, RA )
               D( I ) = RA
               IF( I.GT.1 ) THEN
                  RB = -RS*AB( KU, I )
                  E( I-1 ) = RC*AB( KU, I )
               END IF
               IF( WANTPT )
     $            CALL DROT( N, PT( I, 1 ), LDPT, PT( M+1, 1 ), LDPT,
     $                       RC, RS )
  110       CONTINUE
         ELSE
*
*           Copy off-diagonal elements to E and diagonal elements to D
*
            DO 120 I = 1, MINMN - 1
               E( I ) = AB( KU, I+1 )
  120       CONTINUE
            DO 130 I = 1, MINMN
               D( I ) = AB( KU+1, I )
  130       CONTINUE
         END IF
      ELSE
*
*        A is diagonal. Set elements of E to zero and copy diagonal
*        elements to D.
*
         DO 140 I = 1, MINMN - 1
            E( I ) = ZERO
  140    CONTINUE
         DO 150 I = 1, MINMN
            D( I ) = AB( 1, I )
  150    CONTINUE
      END IF
      RETURN
*
*     End of DGBBRD
*
      END
*> \brief \b DGBCON
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGBCON + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgbcon.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgbcon.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgbcon.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGBCON( NORM, N, KL, KU, AB, LDAB, IPIV, ANORM, RCOND,
*                          WORK, IWORK, INFO )
*
*       .. Scalar Arguments ..
*       CHARACTER          NORM
*       INTEGER            INFO, KL, KU, LDAB, N
*       DOUBLE PRECISION   ANORM, RCOND
*       ..
*       .. Array Arguments ..
*       INTEGER            IPIV( * ), IWORK( * )
*       DOUBLE PRECISION   AB( LDAB, * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGBCON estimates the reciprocal of the condition number of a real
*> general band matrix A, in either the 1-norm or the infinity-norm,
*> using the LU factorization computed by DGBTRF.
*>
*> An estimate is obtained for norm(inv(A)), and the reciprocal of the
*> condition number is computed as
*>    RCOND = 1 / ( norm(A) * norm(inv(A)) ).
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] NORM
*> \verbatim
*>          NORM is CHARACTER*1
*>          Specifies whether the 1-norm condition number or the
*>          infinity-norm condition number is required:
*>          = '1' or 'O':  1-norm;
*>          = 'I':         Infinity-norm.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The order of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in] KL
*> \verbatim
*>          KL is INTEGER
*>          The number of subdiagonals within the band of A.  KL >= 0.
*> \endverbatim
*>
*> \param[in] KU
*> \verbatim
*>          KU is INTEGER
*>          The number of superdiagonals within the band of A.  KU >= 0.
*> \endverbatim
*>
*> \param[in] AB
*> \verbatim
*>          AB is DOUBLE PRECISION array, dimension (LDAB,N)
*>          Details of the LU factorization of the band matrix A, as
*>          computed by DGBTRF.  U is stored as an upper triangular band
*>          matrix with KL+KU superdiagonals in rows 1 to KL+KU+1, and
*>          the multipliers used during the factorization are stored in
*>          rows KL+KU+2 to 2*KL+KU+1.
*> \endverbatim
*>
*> \param[in] LDAB
*> \verbatim
*>          LDAB is INTEGER
*>          The leading dimension of the array AB.  LDAB >= 2*KL+KU+1.
*> \endverbatim
*>
*> \param[in] IPIV
*> \verbatim
*>          IPIV is INTEGER array, dimension (N)
*>          The pivot indices; for 1 <= i <= N, row i of the matrix was
*>          interchanged with row IPIV(i).
*> \endverbatim
*>
*> \param[in] ANORM
*> \verbatim
*>          ANORM is DOUBLE PRECISION
*>          If NORM = '1' or 'O', the 1-norm of the original matrix A.
*>          If NORM = 'I', the infinity-norm of the original matrix A.
*> \endverbatim
*>
*> \param[out] RCOND
*> \verbatim
*>          RCOND is DOUBLE PRECISION
*>          The reciprocal of the condition number of the matrix A,
*>          computed as RCOND = 1/(norm(A) * norm(inv(A))).
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (3*N)
*> \endverbatim
*>
*> \param[out] IWORK
*> \verbatim
*>          IWORK is INTEGER array, dimension (N)
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0: if INFO = -i, the i-th argument had an illegal value
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGBcomputational
*
*  =====================================================================
      SUBROUTINE DGBCON( NORM, N, KL, KU, AB, LDAB, IPIV, ANORM, RCOND,
     $                   WORK, IWORK, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      CHARACTER          NORM
      INTEGER            INFO, KL, KU, LDAB, N
      DOUBLE PRECISION   ANORM, RCOND
*     ..
*     .. Array Arguments ..
      INTEGER            IPIV( * ), IWORK( * )
      DOUBLE PRECISION   AB( LDAB, * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ONE, ZERO
      PARAMETER          ( ONE = 1.0D+0, ZERO = 0.0D+0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            LNOTI, ONENRM
      CHARACTER          NORMIN
      INTEGER            IX, J, JP, KASE, KASE1, KD, LM
      DOUBLE PRECISION   AINVNM, SCALE, SMLNUM, T
*     ..
*     .. Local Arrays ..
      INTEGER            ISAVE( 3 )
*     ..
*     .. External Functions ..
      LOGICAL            LSAME
      INTEGER            IDAMAX
      DOUBLE PRECISION   DDOT, DLAMCH
      EXTERNAL           LSAME, IDAMAX, DDOT, DLAMCH
*     ..
*     .. External Subroutines ..
      EXTERNAL           DAXPY, DLACN2, DLATBS, DRSCL, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          ABS, MIN
*     ..
*     .. Executable Statements ..
*
*     Test the input parameters.
*
      INFO = 0
      ONENRM = NORM.EQ.'1' .OR. LSAME( NORM, 'O' )
      IF( .NOT.ONENRM .AND. .NOT.LSAME( NORM, 'I' ) ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( KL.LT.0 ) THEN
         INFO = -3
      ELSE IF( KU.LT.0 ) THEN
         INFO = -4
      ELSE IF( LDAB.LT.2*KL+KU+1 ) THEN
         INFO = -6
      ELSE IF( ANORM.LT.ZERO ) THEN
         INFO = -8
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGBCON', -INFO )
         RETURN
      END IF
*
*     Quick return if possible
*
      RCOND = ZERO
      IF( N.EQ.0 ) THEN
         RCOND = ONE
         RETURN
      ELSE IF( ANORM.EQ.ZERO ) THEN
         RETURN
      END IF
*
      SMLNUM = DLAMCH( 'Safe minimum' )
*
*     Estimate the norm of inv(A).
*
      AINVNM = ZERO
      NORMIN = 'N'
      IF( ONENRM ) THEN
         KASE1 = 1
      ELSE
         KASE1 = 2
      END IF
      KD = KL + KU + 1
      LNOTI = KL.GT.0
      KASE = 0
   10 CONTINUE
      CALL DLACN2( N, WORK( N+1 ), WORK, IWORK, AINVNM, KASE, ISAVE )
      IF( KASE.NE.0 ) THEN
         IF( KASE.EQ.KASE1 ) THEN
*
*           Multiply by inv(L).
*
            IF( LNOTI ) THEN
               DO 20 J = 1, N - 1
                  LM = MIN( KL, N-J )
                  JP = IPIV( J )
                  T = WORK( JP )
                  IF( JP.NE.J ) THEN
                     WORK( JP ) = WORK( J )
                     WORK( J ) = T
                  END IF
                  CALL DAXPY( LM, -T, AB( KD+1, J ), 1, WORK( J+1 ), 1 )
   20          CONTINUE
            END IF
*
*           Multiply by inv(U).
*
            CALL DLATBS( 'Upper', 'No transpose', 'Non-unit', NORMIN, N,
     $                   KL+KU, AB, LDAB, WORK, SCALE, WORK( 2*N+1 ),
     $                   INFO )
         ELSE
*
*           Multiply by inv(U**T).
*
            CALL DLATBS( 'Upper', 'Transpose', 'Non-unit', NORMIN, N,
     $                   KL+KU, AB, LDAB, WORK, SCALE, WORK( 2*N+1 ),
     $                   INFO )
*
*           Multiply by inv(L**T).
*
            IF( LNOTI ) THEN
               DO 30 J = N - 1, 1, -1
                  LM = MIN( KL, N-J )
                  WORK( J ) = WORK( J ) - DDOT( LM, AB( KD+1, J ), 1,
     $                        WORK( J+1 ), 1 )
                  JP = IPIV( J )
                  IF( JP.NE.J ) THEN
                     T = WORK( JP )
                     WORK( JP ) = WORK( J )
                     WORK( J ) = T
                  END IF
   30          CONTINUE
            END IF
         END IF
*
*        Divide X by 1/SCALE if doing so will not cause overflow.
*
         NORMIN = 'Y'
         IF( SCALE.NE.ONE ) THEN
            IX = IDAMAX( N, WORK, 1 )
            IF( SCALE.LT.ABS( WORK( IX ) )*SMLNUM .OR. SCALE.EQ.ZERO )
     $         GO TO 40
            CALL DRSCL( N, SCALE, WORK, 1 )
         END IF
         GO TO 10
      END IF
*
*     Compute the estimate of the reciprocal condition number.
*
      IF( AINVNM.NE.ZERO )
     $   RCOND = ( ONE / AINVNM ) / ANORM
*
   40 CONTINUE
      RETURN
*
*     End of DGBCON
*
      END
*> \brief \b DGBEQU
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGBEQU + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgbequ.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgbequ.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgbequ.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGBEQU( M, N, KL, KU, AB, LDAB, R, C, ROWCND, COLCND,
*                          AMAX, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, KL, KU, LDAB, M, N
*       DOUBLE PRECISION   AMAX, COLCND, ROWCND
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   AB( LDAB, * ), C( * ), R( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGBEQU computes row and column scalings intended to equilibrate an
*> M-by-N band matrix A and reduce its condition number.  R returns the
*> row scale factors and C the column scale factors, chosen to try to
*> make the largest element in each row and column of the matrix B with
*> elements B(i,j)=R(i)*A(i,j)*C(j) have absolute value 1.
*>
*> R(i) and C(j) are restricted to be between SMLNUM = smallest safe
*> number and BIGNUM = largest safe number.  Use of these scaling
*> factors is not guaranteed to reduce the condition number of A but
*> works well in practice.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A.  M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in] KL
*> \verbatim
*>          KL is INTEGER
*>          The number of subdiagonals within the band of A.  KL >= 0.
*> \endverbatim
*>
*> \param[in] KU
*> \verbatim
*>          KU is INTEGER
*>          The number of superdiagonals within the band of A.  KU >= 0.
*> \endverbatim
*>
*> \param[in] AB
*> \verbatim
*>          AB is DOUBLE PRECISION array, dimension (LDAB,N)
*>          The band matrix A, stored in rows 1 to KL+KU+1.  The j-th
*>          column of A is stored in the j-th column of the array AB as
*>          follows:
*>          AB(ku+1+i-j,j) = A(i,j) for max(1,j-ku)<=i<=min(m,j+kl).
*> \endverbatim
*>
*> \param[in] LDAB
*> \verbatim
*>          LDAB is INTEGER
*>          The leading dimension of the array AB.  LDAB >= KL+KU+1.
*> \endverbatim
*>
*> \param[out] R
*> \verbatim
*>          R is DOUBLE PRECISION array, dimension (M)
*>          If INFO = 0, or INFO > M, R contains the row scale factors
*>          for A.
*> \endverbatim
*>
*> \param[out] C
*> \verbatim
*>          C is DOUBLE PRECISION array, dimension (N)
*>          If INFO = 0, C contains the column scale factors for A.
*> \endverbatim
*>
*> \param[out] ROWCND
*> \verbatim
*>          ROWCND is DOUBLE PRECISION
*>          If INFO = 0 or INFO > M, ROWCND contains the ratio of the
*>          smallest R(i) to the largest R(i).  If ROWCND >= 0.1 and
*>          AMAX is neither too large nor too small, it is not worth
*>          scaling by R.
*> \endverbatim
*>
*> \param[out] COLCND
*> \verbatim
*>          COLCND is DOUBLE PRECISION
*>          If INFO = 0, COLCND contains the ratio of the smallest
*>          C(i) to the largest C(i).  If COLCND >= 0.1, it is not
*>          worth scaling by C.
*> \endverbatim
*>
*> \param[out] AMAX
*> \verbatim
*>          AMAX is DOUBLE PRECISION
*>          Absolute value of largest matrix element.  If AMAX is very
*>          close to overflow or very close to underflow, the matrix
*>          should be scaled.
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value
*>          > 0:  if INFO = i, and i is
*>                <= M:  the i-th row of A is exactly zero
*>                >  M:  the (i-M)-th column of A is exactly zero
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGBcomputational
*
*  =====================================================================
      SUBROUTINE DGBEQU( M, N, KL, KU, AB, LDAB, R, C, ROWCND, COLCND,
     $                   AMAX, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER            INFO, KL, KU, LDAB, M, N
      DOUBLE PRECISION   AMAX, COLCND, ROWCND
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   AB( LDAB, * ), C( * ), R( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ONE, ZERO
      PARAMETER          ( ONE = 1.0D+0, ZERO = 0.0D+0 )
*     ..
*     .. Local Scalars ..
      INTEGER            I, J, KD
      DOUBLE PRECISION   BIGNUM, RCMAX, RCMIN, SMLNUM
*     ..
*     .. External Functions ..
      DOUBLE PRECISION   DLAMCH
      EXTERNAL           DLAMCH
*     ..
*     .. External Subroutines ..
      EXTERNAL           XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          ABS, MAX, MIN
*     ..
*     .. Executable Statements ..
*
*     Test the input parameters
*
      INFO = 0
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( KL.LT.0 ) THEN
         INFO = -3
      ELSE IF( KU.LT.0 ) THEN
         INFO = -4
      ELSE IF( LDAB.LT.KL+KU+1 ) THEN
         INFO = -6
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGBEQU', -INFO )
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( M.EQ.0 .OR. N.EQ.0 ) THEN
         ROWCND = ONE
         COLCND = ONE
         AMAX = ZERO
         RETURN
      END IF
*
*     Get machine constants.
*
      SMLNUM = DLAMCH( 'S' )
      BIGNUM = ONE / SMLNUM
*
*     Compute row scale factors.
*
      DO 10 I = 1, M
         R( I ) = ZERO
   10 CONTINUE
*
*     Find the maximum element in each row.
*
      KD = KU + 1
      DO 30 J = 1, N
         DO 20 I = MAX( J-KU, 1 ), MIN( J+KL, M )
            R( I ) = MAX( R( I ), ABS( AB( KD+I-J, J ) ) )
   20    CONTINUE
   30 CONTINUE
*
*     Find the maximum and minimum scale factors.
*
      RCMIN = BIGNUM
      RCMAX = ZERO
      DO 40 I = 1, M
         RCMAX = MAX( RCMAX, R( I ) )
         RCMIN = MIN( RCMIN, R( I ) )
   40 CONTINUE
      AMAX = RCMAX
*
      IF( RCMIN.EQ.ZERO ) THEN
*
*        Find the first zero scale factor and return an error code.
*
         DO 50 I = 1, M
            IF( R( I ).EQ.ZERO ) THEN
               INFO = I
               RETURN
            END IF
   50    CONTINUE
      ELSE
*
*        Invert the scale factors.
*
         DO 60 I = 1, M
            R( I ) = ONE / MIN( MAX( R( I ), SMLNUM ), BIGNUM )
   60    CONTINUE
*
*        Compute ROWCND = min(R(I)) / max(R(I))
*
         ROWCND = MAX( RCMIN, SMLNUM ) / MIN( RCMAX, BIGNUM )
      END IF
*
*     Compute column scale factors
*
      DO 70 J = 1, N
         C( J ) = ZERO
   70 CONTINUE
*
*     Find the maximum element in each column,
*     assuming the row scaling computed above.
*
      KD = KU + 1
      DO 90 J = 1, N
         DO 80 I = MAX( J-KU, 1 ), MIN( J+KL, M )
            C( J ) = MAX( C( J ), ABS( AB( KD+I-J, J ) )*R( I ) )
   80    CONTINUE
   90 CONTINUE
*
*     Find the maximum and minimum scale factors.
*
      RCMIN = BIGNUM
      RCMAX = ZERO
      DO 100 J = 1, N
         RCMIN = MIN( RCMIN, C( J ) )
         RCMAX = MAX( RCMAX, C( J ) )
  100 CONTINUE
*
      IF( RCMIN.EQ.ZERO ) THEN
*
*        Find the first zero scale factor and return an error code.
*
         DO 110 J = 1, N
            IF( C( J ).EQ.ZERO ) THEN
               INFO = M + J
               RETURN
            END IF
  110    CONTINUE
      ELSE
*
*        Invert the scale factors.
*
         DO 120 J = 1, N
            C( J ) = ONE / MIN( MAX( C( J ), SMLNUM ), BIGNUM )
  120    CONTINUE
*
*        Compute COLCND = min(C(J)) / max(C(J))
*
         COLCND = MAX( RCMIN, SMLNUM ) / MIN( RCMAX, BIGNUM )
      END IF
*
      RETURN
*
*     End of DGBEQU
*
      END
*> \brief \b DGBEQUB
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGBEQUB + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgbequb.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgbequb.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgbequb.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGBEQUB( M, N, KL, KU, AB, LDAB, R, C, ROWCND, COLCND,
*                           AMAX, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, KL, KU, LDAB, M, N
*       DOUBLE PRECISION   AMAX, COLCND, ROWCND
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   AB( LDAB, * ), C( * ), R( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGBEQUB computes row and column scalings intended to equilibrate an
*> M-by-N matrix A and reduce its condition number.  R returns the row
*> scale factors and C the column scale factors, chosen to try to make
*> the largest element in each row and column of the matrix B with
*> elements B(i,j)=R(i)*A(i,j)*C(j) have an absolute value of at most
*> the radix.
*>
*> R(i) and C(j) are restricted to be a power of the radix between
*> SMLNUM = smallest safe number and BIGNUM = largest safe number.  Use
*> of these scaling factors is not guaranteed to reduce the condition
*> number of A but works well in practice.
*>
*> This routine differs from DGEEQU by restricting the scaling factors
*> to a power of the radix.  Barring over- and underflow, scaling by
*> these factors introduces no additional rounding errors.  However, the
*> scaled entries' magnitudes are no longer approximately 1 but lie
*> between sqrt(radix) and 1/sqrt(radix).
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A.  M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in] KL
*> \verbatim
*>          KL is INTEGER
*>          The number of subdiagonals within the band of A.  KL >= 0.
*> \endverbatim
*>
*> \param[in] KU
*> \verbatim
*>          KU is INTEGER
*>          The number of superdiagonals within the band of A.  KU >= 0.
*> \endverbatim
*>
*> \param[in] AB
*> \verbatim
*>          AB is DOUBLE PRECISION array, dimension (LDAB,N)
*>          On entry, the matrix A in band storage, in rows 1 to KL+KU+1.
*>          The j-th column of A is stored in the j-th column of the
*>          array AB as follows:
*>          AB(KU+1+i-j,j) = A(i,j) for max(1,j-KU)<=i<=min(N,j+kl)
*> \endverbatim
*>
*> \param[in] LDAB
*> \verbatim
*>          LDAB is INTEGER
*>          The leading dimension of the array A.  LDAB >= max(1,M).
*> \endverbatim
*>
*> \param[out] R
*> \verbatim
*>          R is DOUBLE PRECISION array, dimension (M)
*>          If INFO = 0 or INFO > M, R contains the row scale factors
*>          for A.
*> \endverbatim
*>
*> \param[out] C
*> \verbatim
*>          C is DOUBLE PRECISION array, dimension (N)
*>          If INFO = 0,  C contains the column scale factors for A.
*> \endverbatim
*>
*> \param[out] ROWCND
*> \verbatim
*>          ROWCND is DOUBLE PRECISION
*>          If INFO = 0 or INFO > M, ROWCND contains the ratio of the
*>          smallest R(i) to the largest R(i).  If ROWCND >= 0.1 and
*>          AMAX is neither too large nor too small, it is not worth
*>          scaling by R.
*> \endverbatim
*>
*> \param[out] COLCND
*> \verbatim
*>          COLCND is DOUBLE PRECISION
*>          If INFO = 0, COLCND contains the ratio of the smallest
*>          C(i) to the largest C(i).  If COLCND >= 0.1, it is not
*>          worth scaling by C.
*> \endverbatim
*>
*> \param[out] AMAX
*> \verbatim
*>          AMAX is DOUBLE PRECISION
*>          Absolute value of largest matrix element.  If AMAX is very
*>          close to overflow or very close to underflow, the matrix
*>          should be scaled.
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value
*>          > 0:  if INFO = i,  and i is
*>                <= M:  the i-th row of A is exactly zero
*>                >  M:  the (i-M)-th column of A is exactly zero
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGBcomputational
*
*  =====================================================================
      SUBROUTINE DGBEQUB( M, N, KL, KU, AB, LDAB, R, C, ROWCND, COLCND,
     $                    AMAX, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER            INFO, KL, KU, LDAB, M, N
      DOUBLE PRECISION   AMAX, COLCND, ROWCND
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   AB( LDAB, * ), C( * ), R( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ONE, ZERO
      PARAMETER          ( ONE = 1.0D+0, ZERO = 0.0D+0 )
*     ..
*     .. Local Scalars ..
      INTEGER            I, J, KD
      DOUBLE PRECISION   BIGNUM, RCMAX, RCMIN, SMLNUM, RADIX, LOGRDX
*     ..
*     .. External Functions ..
      DOUBLE PRECISION   DLAMCH
      EXTERNAL           DLAMCH
*     ..
*     .. External Subroutines ..
      EXTERNAL           XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          ABS, MAX, MIN, LOG
*     ..
*     .. Executable Statements ..
*
*     Test the input parameters.
*
      INFO = 0
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( KL.LT.0 ) THEN
         INFO = -3
      ELSE IF( KU.LT.0 ) THEN
         INFO = -4
      ELSE IF( LDAB.LT.KL+KU+1 ) THEN
         INFO = -6
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGBEQUB', -INFO )
         RETURN
      END IF
*
*     Quick return if possible.
*
      IF( M.EQ.0 .OR. N.EQ.0 ) THEN
         ROWCND = ONE
         COLCND = ONE
         AMAX = ZERO
         RETURN
      END IF
*
*     Get machine constants.  Assume SMLNUM is a power of the radix.
*
      SMLNUM = DLAMCH( 'S' )
      BIGNUM = ONE / SMLNUM
      RADIX = DLAMCH( 'B' )
      LOGRDX = LOG(RADIX)
*
*     Compute row scale factors.
*
      DO 10 I = 1, M
         R( I ) = ZERO
   10 CONTINUE
*
*     Find the maximum element in each row.
*
      KD = KU + 1
      DO 30 J = 1, N
         DO 20 I = MAX( J-KU, 1 ), MIN( J+KL, M )
            R( I ) = MAX( R( I ), ABS( AB( KD+I-J, J ) ) )
   20    CONTINUE
   30 CONTINUE
      DO I = 1, M
         IF( R( I ).GT.ZERO ) THEN
            R( I ) = RADIX**INT( LOG( R( I ) ) / LOGRDX )
         END IF
      END DO
*
*     Find the maximum and minimum scale factors.
*
      RCMIN = BIGNUM
      RCMAX = ZERO
      DO 40 I = 1, M
         RCMAX = MAX( RCMAX, R( I ) )
         RCMIN = MIN( RCMIN, R( I ) )
   40 CONTINUE
      AMAX = RCMAX
*
      IF( RCMIN.EQ.ZERO ) THEN
*
*        Find the first zero scale factor and return an error code.
*
         DO 50 I = 1, M
            IF( R( I ).EQ.ZERO ) THEN
               INFO = I
               RETURN
            END IF
   50    CONTINUE
      ELSE
*
*        Invert the scale factors.
*
         DO 60 I = 1, M
            R( I ) = ONE / MIN( MAX( R( I ), SMLNUM ), BIGNUM )
   60    CONTINUE
*
*        Compute ROWCND = min(R(I)) / max(R(I)).
*
         ROWCND = MAX( RCMIN, SMLNUM ) / MIN( RCMAX, BIGNUM )
      END IF
*
*     Compute column scale factors.
*
      DO 70 J = 1, N
         C( J ) = ZERO
   70 CONTINUE
*
*     Find the maximum element in each column,
*     assuming the row scaling computed above.
*
      DO 90 J = 1, N
         DO 80 I = MAX( J-KU, 1 ), MIN( J+KL, M )
            C( J ) = MAX( C( J ), ABS( AB( KD+I-J, J ) )*R( I ) )
   80    CONTINUE
         IF( C( J ).GT.ZERO ) THEN
            C( J ) = RADIX**INT( LOG( C( J ) ) / LOGRDX )
         END IF
   90 CONTINUE
*
*     Find the maximum and minimum scale factors.
*
      RCMIN = BIGNUM
      RCMAX = ZERO
      DO 100 J = 1, N
         RCMIN = MIN( RCMIN, C( J ) )
         RCMAX = MAX( RCMAX, C( J ) )
  100 CONTINUE
*
      IF( RCMIN.EQ.ZERO ) THEN
*
*        Find the first zero scale factor and return an error code.
*
         DO 110 J = 1, N
            IF( C( J ).EQ.ZERO ) THEN
               INFO = M + J
               RETURN
            END IF
  110    CONTINUE
      ELSE
*
*        Invert the scale factors.
*
         DO 120 J = 1, N
            C( J ) = ONE / MIN( MAX( C( J ), SMLNUM ), BIGNUM )
  120    CONTINUE
*
*        Compute COLCND = min(C(J)) / max(C(J)).
*
         COLCND = MAX( RCMIN, SMLNUM ) / MIN( RCMAX, BIGNUM )
      END IF
*
      RETURN
*
*     End of DGBEQUB
*
      END
*> \brief \b DGBRFS
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGBRFS + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgbrfs.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgbrfs.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgbrfs.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGBRFS( TRANS, N, KL, KU, NRHS, AB, LDAB, AFB, LDAFB,
*                          IPIV, B, LDB, X, LDX, FERR, BERR, WORK, IWORK,
*                          INFO )
*
*       .. Scalar Arguments ..
*       CHARACTER          TRANS
*       INTEGER            INFO, KL, KU, LDAB, LDAFB, LDB, LDX, N, NRHS
*       ..
*       .. Array Arguments ..
*       INTEGER            IPIV( * ), IWORK( * )
*       DOUBLE PRECISION   AB( LDAB, * ), AFB( LDAFB, * ), B( LDB, * ),
*      $                   BERR( * ), FERR( * ), WORK( * ), X( LDX, * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGBRFS improves the computed solution to a system of linear
*> equations when the coefficient matrix is banded, and provides
*> error bounds and backward error estimates for the solution.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] TRANS
*> \verbatim
*>          TRANS is CHARACTER*1
*>          Specifies the form of the system of equations:
*>          = 'N':  A * X = B     (No transpose)
*>          = 'T':  A**T * X = B  (Transpose)
*>          = 'C':  A**H * X = B  (Conjugate transpose = Transpose)
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The order of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in] KL
*> \verbatim
*>          KL is INTEGER
*>          The number of subdiagonals within the band of A.  KL >= 0.
*> \endverbatim
*>
*> \param[in] KU
*> \verbatim
*>          KU is INTEGER
*>          The number of superdiagonals within the band of A.  KU >= 0.
*> \endverbatim
*>
*> \param[in] NRHS
*> \verbatim
*>          NRHS is INTEGER
*>          The number of right hand sides, i.e., the number of columns
*>          of the matrices B and X.  NRHS >= 0.
*> \endverbatim
*>
*> \param[in] AB
*> \verbatim
*>          AB is DOUBLE PRECISION array, dimension (LDAB,N)
*>          The original band matrix A, stored in rows 1 to KL+KU+1.
*>          The j-th column of A is stored in the j-th column of the
*>          array AB as follows:
*>          AB(ku+1+i-j,j) = A(i,j) for max(1,j-ku)<=i<=min(n,j+kl).
*> \endverbatim
*>
*> \param[in] LDAB
*> \verbatim
*>          LDAB is INTEGER
*>          The leading dimension of the array AB.  LDAB >= KL+KU+1.
*> \endverbatim
*>
*> \param[in] AFB
*> \verbatim
*>          AFB is DOUBLE PRECISION array, dimension (LDAFB,N)
*>          Details of the LU factorization of the band matrix A, as
*>          computed by DGBTRF.  U is stored as an upper triangular band
*>          matrix with KL+KU superdiagonals in rows 1 to KL+KU+1, and
*>          the multipliers used during the factorization are stored in
*>          rows KL+KU+2 to 2*KL+KU+1.
*> \endverbatim
*>
*> \param[in] LDAFB
*> \verbatim
*>          LDAFB is INTEGER
*>          The leading dimension of the array AFB.  LDAFB >= 2*KL*KU+1.
*> \endverbatim
*>
*> \param[in] IPIV
*> \verbatim
*>          IPIV is INTEGER array, dimension (N)
*>          The pivot indices from DGBTRF; for 1<=i<=N, row i of the
*>          matrix was interchanged with row IPIV(i).
*> \endverbatim
*>
*> \param[in] B
*> \verbatim
*>          B is DOUBLE PRECISION array, dimension (LDB,NRHS)
*>          The right hand side matrix B.
*> \endverbatim
*>
*> \param[in] LDB
*> \verbatim
*>          LDB is INTEGER
*>          The leading dimension of the array B.  LDB >= max(1,N).
*> \endverbatim
*>
*> \param[in,out] X
*> \verbatim
*>          X is DOUBLE PRECISION array, dimension (LDX,NRHS)
*>          On entry, the solution matrix X, as computed by DGBTRS.
*>          On exit, the improved solution matrix X.
*> \endverbatim
*>
*> \param[in] LDX
*> \verbatim
*>          LDX is INTEGER
*>          The leading dimension of the array X.  LDX >= max(1,N).
*> \endverbatim
*>
*> \param[out] FERR
*> \verbatim
*>          FERR is DOUBLE PRECISION array, dimension (NRHS)
*>          The estimated forward error bound for each solution vector
*>          X(j) (the j-th column of the solution matrix X).
*>          If XTRUE is the true solution corresponding to X(j), FERR(j)
*>          is an estimated upper bound for the magnitude of the largest
*>          element in (X(j) - XTRUE) divided by the magnitude of the
*>          largest element in X(j).  The estimate is as reliable as
*>          the estimate for RCOND, and is almost always a slight
*>          overestimate of the true error.
*> \endverbatim
*>
*> \param[out] BERR
*> \verbatim
*>          BERR is DOUBLE PRECISION array, dimension (NRHS)
*>          The componentwise relative backward error of each solution
*>          vector X(j) (i.e., the smallest relative change in
*>          any element of A or B that makes X(j) an exact solution).
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (3*N)
*> \endverbatim
*>
*> \param[out] IWORK
*> \verbatim
*>          IWORK is INTEGER array, dimension (N)
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value
*> \endverbatim
*
*> \par Internal Parameters:
*  =========================
*>
*> \verbatim
*>  ITMAX is the maximum number of steps of iterative refinement.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGBcomputational
*
*  =====================================================================
      SUBROUTINE DGBRFS( TRANS, N, KL, KU, NRHS, AB, LDAB, AFB, LDAFB,
     $                   IPIV, B, LDB, X, LDX, FERR, BERR, WORK, IWORK,
     $                   INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      CHARACTER          TRANS
      INTEGER            INFO, KL, KU, LDAB, LDAFB, LDB, LDX, N, NRHS
*     ..
*     .. Array Arguments ..
      INTEGER            IPIV( * ), IWORK( * )
      DOUBLE PRECISION   AB( LDAB, * ), AFB( LDAFB, * ), B( LDB, * ),
     $                   BERR( * ), FERR( * ), WORK( * ), X( LDX, * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      INTEGER            ITMAX
      PARAMETER          ( ITMAX = 5 )
      DOUBLE PRECISION   ZERO
      PARAMETER          ( ZERO = 0.0D+0 )
      DOUBLE PRECISION   ONE
      PARAMETER          ( ONE = 1.0D+0 )
      DOUBLE PRECISION   TWO
      PARAMETER          ( TWO = 2.0D+0 )
      DOUBLE PRECISION   THREE
      PARAMETER          ( THREE = 3.0D+0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            NOTRAN
      CHARACTER          TRANST
      INTEGER            COUNT, I, J, K, KASE, KK, NZ
      DOUBLE PRECISION   EPS, LSTRES, S, SAFE1, SAFE2, SAFMIN, XK
*     ..
*     .. Local Arrays ..
      INTEGER            ISAVE( 3 )
*     ..
*     .. External Subroutines ..
      EXTERNAL           DAXPY, DCOPY, DGBMV, DGBTRS, DLACN2, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          ABS, MAX, MIN
*     ..
*     .. External Functions ..
      LOGICAL            LSAME
      DOUBLE PRECISION   DLAMCH
      EXTERNAL           LSAME, DLAMCH
*     ..
*     .. Executable Statements ..
*
*     Test the input parameters.
*
      INFO = 0
      NOTRAN = LSAME( TRANS, 'N' )
      IF( .NOT.NOTRAN .AND. .NOT.LSAME( TRANS, 'T' ) .AND. .NOT.
     $    LSAME( TRANS, 'C' ) ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( KL.LT.0 ) THEN
         INFO = -3
      ELSE IF( KU.LT.0 ) THEN
         INFO = -4
      ELSE IF( NRHS.LT.0 ) THEN
         INFO = -5
      ELSE IF( LDAB.LT.KL+KU+1 ) THEN
         INFO = -7
      ELSE IF( LDAFB.LT.2*KL+KU+1 ) THEN
         INFO = -9
      ELSE IF( LDB.LT.MAX( 1, N ) ) THEN
         INFO = -12
      ELSE IF( LDX.LT.MAX( 1, N ) ) THEN
         INFO = -14
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGBRFS', -INFO )
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( N.EQ.0 .OR. NRHS.EQ.0 ) THEN
         DO 10 J = 1, NRHS
            FERR( J ) = ZERO
            BERR( J ) = ZERO
   10    CONTINUE
         RETURN
      END IF
*
      IF( NOTRAN ) THEN
         TRANST = 'T'
      ELSE
         TRANST = 'N'
      END IF
*
*     NZ = maximum number of nonzero elements in each row of A, plus 1
*
      NZ = MIN( KL+KU+2, N+1 )
      EPS = DLAMCH( 'Epsilon' )
      SAFMIN = DLAMCH( 'Safe minimum' )
      SAFE1 = NZ*SAFMIN
      SAFE2 = SAFE1 / EPS
*
*     Do for each right hand side
*
      DO 140 J = 1, NRHS
*
         COUNT = 1
         LSTRES = THREE
   20    CONTINUE
*
*        Loop until stopping criterion is satisfied.
*
*        Compute residual R = B - op(A) * X,
*        where op(A) = A, A**T, or A**H, depending on TRANS.
*
         CALL DCOPY( N, B( 1, J ), 1, WORK( N+1 ), 1 )
         CALL DGBMV( TRANS, N, N, KL, KU, -ONE, AB, LDAB, X( 1, J ), 1,
     $               ONE, WORK( N+1 ), 1 )
*
*        Compute componentwise relative backward error from formula
*
*        max(i) ( abs(R(i)) / ( abs(op(A))*abs(X) + abs(B) )(i) )
*
*        where abs(Z) is the componentwise absolute value of the matrix
*        or vector Z.  If the i-th component of the denominator is less
*        than SAFE2, then SAFE1 is added to the i-th components of the
*        numerator and denominator before dividing.
*
         DO 30 I = 1, N
            WORK( I ) = ABS( B( I, J ) )
   30    CONTINUE
*
*        Compute abs(op(A))*abs(X) + abs(B).
*
         IF( NOTRAN ) THEN
            DO 50 K = 1, N
               KK = KU + 1 - K
               XK = ABS( X( K, J ) )
               DO 40 I = MAX( 1, K-KU ), MIN( N, K+KL )
                  WORK( I ) = WORK( I ) + ABS( AB( KK+I, K ) )*XK
   40          CONTINUE
   50       CONTINUE
         ELSE
            DO 70 K = 1, N
               S = ZERO
               KK = KU + 1 - K
               DO 60 I = MAX( 1, K-KU ), MIN( N, K+KL )
                  S = S + ABS( AB( KK+I, K ) )*ABS( X( I, J ) )
   60          CONTINUE
               WORK( K ) = WORK( K ) + S
   70       CONTINUE
         END IF
         S = ZERO
         DO 80 I = 1, N
            IF( WORK( I ).GT.SAFE2 ) THEN
               S = MAX( S, ABS( WORK( N+I ) ) / WORK( I ) )
            ELSE
               S = MAX( S, ( ABS( WORK( N+I ) )+SAFE1 ) /
     $             ( WORK( I )+SAFE1 ) )
            END IF
   80    CONTINUE
         BERR( J ) = S
*
*        Test stopping criterion. Continue iterating if
*           1) The residual BERR(J) is larger than machine epsilon, and
*           2) BERR(J) decreased by at least a factor of 2 during the
*              last iteration, and
*           3) At most ITMAX iterations tried.
*
         IF( BERR( J ).GT.EPS .AND. TWO*BERR( J ).LE.LSTRES .AND.
     $       COUNT.LE.ITMAX ) THEN
*
*           Update solution and try again.
*
            CALL DGBTRS( TRANS, N, KL, KU, 1, AFB, LDAFB, IPIV,
     $                   WORK( N+1 ), N, INFO )
            CALL DAXPY( N, ONE, WORK( N+1 ), 1, X( 1, J ), 1 )
            LSTRES = BERR( J )
            COUNT = COUNT + 1
            GO TO 20
         END IF
*
*        Bound error from formula
*
*        norm(X - XTRUE) / norm(X) .le. FERR =
*        norm( abs(inv(op(A)))*
*           ( abs(R) + NZ*EPS*( abs(op(A))*abs(X)+abs(B) ))) / norm(X)
*
*        where
*          norm(Z) is the magnitude of the largest component of Z
*          inv(op(A)) is the inverse of op(A)
*          abs(Z) is the componentwise absolute value of the matrix or
*             vector Z
*          NZ is the maximum number of nonzeros in any row of A, plus 1
*          EPS is machine epsilon
*
*        The i-th component of abs(R)+NZ*EPS*(abs(op(A))*abs(X)+abs(B))
*        is incremented by SAFE1 if the i-th component of
*        abs(op(A))*abs(X) + abs(B) is less than SAFE2.
*
*        Use DLACN2 to estimate the infinity-norm of the matrix
*           inv(op(A)) * diag(W),
*        where W = abs(R) + NZ*EPS*( abs(op(A))*abs(X)+abs(B) )))
*
         DO 90 I = 1, N
            IF( WORK( I ).GT.SAFE2 ) THEN
               WORK( I ) = ABS( WORK( N+I ) ) + NZ*EPS*WORK( I )
            ELSE
               WORK( I ) = ABS( WORK( N+I ) ) + NZ*EPS*WORK( I ) + SAFE1
            END IF
   90    CONTINUE
*
         KASE = 0
  100    CONTINUE
         CALL DLACN2( N, WORK( 2*N+1 ), WORK( N+1 ), IWORK, FERR( J ),
     $                KASE, ISAVE )
         IF( KASE.NE.0 ) THEN
            IF( KASE.EQ.1 ) THEN
*
*              Multiply by diag(W)*inv(op(A)**T).
*
               CALL DGBTRS( TRANST, N, KL, KU, 1, AFB, LDAFB, IPIV,
     $                      WORK( N+1 ), N, INFO )
               DO 110 I = 1, N
                  WORK( N+I ) = WORK( N+I )*WORK( I )
  110          CONTINUE
            ELSE
*
*              Multiply by inv(op(A))*diag(W).
*
               DO 120 I = 1, N
                  WORK( N+I ) = WORK( N+I )*WORK( I )
  120          CONTINUE
               CALL DGBTRS( TRANS, N, KL, KU, 1, AFB, LDAFB, IPIV,
     $                      WORK( N+1 ), N, INFO )
            END IF
            GO TO 100
         END IF
*
*        Normalize error.
*
         LSTRES = ZERO
         DO 130 I = 1, N
            LSTRES = MAX( LSTRES, ABS( X( I, J ) ) )
  130    CONTINUE
         IF( LSTRES.NE.ZERO )
     $      FERR( J ) = FERR( J ) / LSTRES
*
  140 CONTINUE
*
      RETURN
*
*     End of DGBRFS
*
      END
*> \brief <b> DGBSV computes the solution to system of linear equations A * X = B for GB matrices</b> (simple driver)
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGBSV + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgbsv.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgbsv.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgbsv.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGBSV( N, KL, KU, NRHS, AB, LDAB, IPIV, B, LDB, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, KL, KU, LDAB, LDB, N, NRHS
*       ..
*       .. Array Arguments ..
*       INTEGER            IPIV( * )
*       DOUBLE PRECISION   AB( LDAB, * ), B( LDB, * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGBSV computes the solution to a real system of linear equations
*> A * X = B, where A is a band matrix of order N with KL subdiagonals
*> and KU superdiagonals, and X and B are N-by-NRHS matrices.
*>
*> The LU decomposition with partial pivoting and row interchanges is
*> used to factor A as A = L * U, where L is a product of permutation
*> and unit lower triangular matrices with KL subdiagonals, and U is
*> upper triangular with KL+KU superdiagonals.  The factored form of A
*> is then used to solve the system of equations A * X = B.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of linear equations, i.e., the order of the
*>          matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in] KL
*> \verbatim
*>          KL is INTEGER
*>          The number of subdiagonals within the band of A.  KL >= 0.
*> \endverbatim
*>
*> \param[in] KU
*> \verbatim
*>          KU is INTEGER
*>          The number of superdiagonals within the band of A.  KU >= 0.
*> \endverbatim
*>
*> \param[in] NRHS
*> \verbatim
*>          NRHS is INTEGER
*>          The number of right hand sides, i.e., the number of columns
*>          of the matrix B.  NRHS >= 0.
*> \endverbatim
*>
*> \param[in,out] AB
*> \verbatim
*>          AB is DOUBLE PRECISION array, dimension (LDAB,N)
*>          On entry, the matrix A in band storage, in rows KL+1 to
*>          2*KL+KU+1; rows 1 to KL of the array need not be set.
*>          The j-th column of A is stored in the j-th column of the
*>          array AB as follows:
*>          AB(KL+KU+1+i-j,j) = A(i,j) for max(1,j-KU)<=i<=min(N,j+KL)
*>          On exit, details of the factorization: U is stored as an
*>          upper triangular band matrix with KL+KU superdiagonals in
*>          rows 1 to KL+KU+1, and the multipliers used during the
*>          factorization are stored in rows KL+KU+2 to 2*KL+KU+1.
*>          See below for further details.
*> \endverbatim
*>
*> \param[in] LDAB
*> \verbatim
*>          LDAB is INTEGER
*>          The leading dimension of the array AB.  LDAB >= 2*KL+KU+1.
*> \endverbatim
*>
*> \param[out] IPIV
*> \verbatim
*>          IPIV is INTEGER array, dimension (N)
*>          The pivot indices that define the permutation matrix P;
*>          row i of the matrix was interchanged with row IPIV(i).
*> \endverbatim
*>
*> \param[in,out] B
*> \verbatim
*>          B is DOUBLE PRECISION array, dimension (LDB,NRHS)
*>          On entry, the N-by-NRHS right hand side matrix B.
*>          On exit, if INFO = 0, the N-by-NRHS solution matrix X.
*> \endverbatim
*>
*> \param[in] LDB
*> \verbatim
*>          LDB is INTEGER
*>          The leading dimension of the array B.  LDB >= max(1,N).
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value
*>          > 0:  if INFO = i, U(i,i) is exactly zero.  The factorization
*>                has been completed, but the factor U is exactly
*>                singular, and the solution has not been computed.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGBsolve
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>  The band storage scheme is illustrated by the following example, when
*>  M = N = 6, KL = 2, KU = 1:
*>
*>  On entry:                       On exit:
*>
*>      *    *    *    +    +    +       *    *    *   u14  u25  u36
*>      *    *    +    +    +    +       *    *   u13  u24  u35  u46
*>      *   a12  a23  a34  a45  a56      *   u12  u23  u34  u45  u56
*>     a11  a22  a33  a44  a55  a66     u11  u22  u33  u44  u55  u66
*>     a21  a32  a43  a54  a65   *      m21  m32  m43  m54  m65   *
*>     a31  a42  a53  a64   *    *      m31  m42  m53  m64   *    *
*>
*>  Array elements marked * are not used by the routine; elements marked
*>  + need not be set on entry, but are required by the routine to store
*>  elements of U because of fill-in resulting from the row interchanges.
*> \endverbatim
*>
*  =====================================================================
      SUBROUTINE DGBSV( N, KL, KU, NRHS, AB, LDAB, IPIV, B, LDB, INFO )
*
*  -- LAPACK driver routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER            INFO, KL, KU, LDAB, LDB, N, NRHS
*     ..
*     .. Array Arguments ..
      INTEGER            IPIV( * )
      DOUBLE PRECISION   AB( LDAB, * ), B( LDB, * )
*     ..
*
*  =====================================================================
*
*     .. External Subroutines ..
      EXTERNAL           DGBTRF, DGBTRS, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX
*     ..
*     .. Executable Statements ..
*
*     Test the input parameters.
*
      INFO = 0
      IF( N.LT.0 ) THEN
         INFO = -1
      ELSE IF( KL.LT.0 ) THEN
         INFO = -2
      ELSE IF( KU.LT.0 ) THEN
         INFO = -3
      ELSE IF( NRHS.LT.0 ) THEN
         INFO = -4
      ELSE IF( LDAB.LT.2*KL+KU+1 ) THEN
         INFO = -6
      ELSE IF( LDB.LT.MAX( N, 1 ) ) THEN
         INFO = -9
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGBSV ', -INFO )
         RETURN
      END IF
*
*     Compute the LU factorization of the band matrix A.
*
      CALL DGBTRF( N, N, KL, KU, AB, LDAB, IPIV, INFO )
      IF( INFO.EQ.0 ) THEN
*
*        Solve the system A*X = B, overwriting B with X.
*
         CALL DGBTRS( 'No transpose', N, KL, KU, NRHS, AB, LDAB, IPIV,
     $                B, LDB, INFO )
      END IF
      RETURN
*
*     End of DGBSV
*
      END
*> \brief <b> DGBSVX computes the solution to system of linear equations A * X = B for GB matrices</b>
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGBSVX + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgbsvx.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgbsvx.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgbsvx.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGBSVX( FACT, TRANS, N, KL, KU, NRHS, AB, LDAB, AFB,
*                          LDAFB, IPIV, EQUED, R, C, B, LDB, X, LDX,
*                          RCOND, FERR, BERR, WORK, IWORK, INFO )
*
*       .. Scalar Arguments ..
*       CHARACTER          EQUED, FACT, TRANS
*       INTEGER            INFO, KL, KU, LDAB, LDAFB, LDB, LDX, N, NRHS
*       DOUBLE PRECISION   RCOND
*       ..
*       .. Array Arguments ..
*       INTEGER            IPIV( * ), IWORK( * )
*       DOUBLE PRECISION   AB( LDAB, * ), AFB( LDAFB, * ), B( LDB, * ),
*      $                   BERR( * ), C( * ), FERR( * ), R( * ),
*      $                   WORK( * ), X( LDX, * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGBSVX uses the LU factorization to compute the solution to a real
*> system of linear equations A * X = B, A**T * X = B, or A**H * X = B,
*> where A is a band matrix of order N with KL subdiagonals and KU
*> superdiagonals, and X and B are N-by-NRHS matrices.
*>
*> Error bounds on the solution and a condition estimate are also
*> provided.
*> \endverbatim
*
*> \par Description:
*  =================
*>
*> \verbatim
*>
*> The following steps are performed by this subroutine:
*>
*> 1. If FACT = 'E', real scaling factors are computed to equilibrate
*>    the system:
*>       TRANS = 'N':  diag(R)*A*diag(C)     *inv(diag(C))*X = diag(R)*B
*>       TRANS = 'T': (diag(R)*A*diag(C))**T *inv(diag(R))*X = diag(C)*B
*>       TRANS = 'C': (diag(R)*A*diag(C))**H *inv(diag(R))*X = diag(C)*B
*>    Whether or not the system will be equilibrated depends on the
*>    scaling of the matrix A, but if equilibration is used, A is
*>    overwritten by diag(R)*A*diag(C) and B by diag(R)*B (if TRANS='N')
*>    or diag(C)*B (if TRANS = 'T' or 'C').
*>
*> 2. If FACT = 'N' or 'E', the LU decomposition is used to factor the
*>    matrix A (after equilibration if FACT = 'E') as
*>       A = L * U,
*>    where L is a product of permutation and unit lower triangular
*>    matrices with KL subdiagonals, and U is upper triangular with
*>    KL+KU superdiagonals.
*>
*> 3. If some U(i,i)=0, so that U is exactly singular, then the routine
*>    returns with INFO = i. Otherwise, the factored form of A is used
*>    to estimate the condition number of the matrix A.  If the
*>    reciprocal of the condition number is less than machine precision,
*>    INFO = N+1 is returned as a warning, but the routine still goes on
*>    to solve for X and compute error bounds as described below.
*>
*> 4. The system of equations is solved for X using the factored form
*>    of A.
*>
*> 5. Iterative refinement is applied to improve the computed solution
*>    matrix and calculate error bounds and backward error estimates
*>    for it.
*>
*> 6. If equilibration was used, the matrix X is premultiplied by
*>    diag(C) (if TRANS = 'N') or diag(R) (if TRANS = 'T' or 'C') so
*>    that it solves the original system before equilibration.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] FACT
*> \verbatim
*>          FACT is CHARACTER*1
*>          Specifies whether or not the factored form of the matrix A is
*>          supplied on entry, and if not, whether the matrix A should be
*>          equilibrated before it is factored.
*>          = 'F':  On entry, AFB and IPIV contain the factored form of
*>                  A.  If EQUED is not 'N', the matrix A has been
*>                  equilibrated with scaling factors given by R and C.
*>                  AB, AFB, and IPIV are not modified.
*>          = 'N':  The matrix A will be copied to AFB and factored.
*>          = 'E':  The matrix A will be equilibrated if necessary, then
*>                  copied to AFB and factored.
*> \endverbatim
*>
*> \param[in] TRANS
*> \verbatim
*>          TRANS is CHARACTER*1
*>          Specifies the form of the system of equations.
*>          = 'N':  A * X = B     (No transpose)
*>          = 'T':  A**T * X = B  (Transpose)
*>          = 'C':  A**H * X = B  (Transpose)
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of linear equations, i.e., the order of the
*>          matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in] KL
*> \verbatim
*>          KL is INTEGER
*>          The number of subdiagonals within the band of A.  KL >= 0.
*> \endverbatim
*>
*> \param[in] KU
*> \verbatim
*>          KU is INTEGER
*>          The number of superdiagonals within the band of A.  KU >= 0.
*> \endverbatim
*>
*> \param[in] NRHS
*> \verbatim
*>          NRHS is INTEGER
*>          The number of right hand sides, i.e., the number of columns
*>          of the matrices B and X.  NRHS >= 0.
*> \endverbatim
*>
*> \param[in,out] AB
*> \verbatim
*>          AB is DOUBLE PRECISION array, dimension (LDAB,N)
*>          On entry, the matrix A in band storage, in rows 1 to KL+KU+1.
*>          The j-th column of A is stored in the j-th column of the
*>          array AB as follows:
*>          AB(KU+1+i-j,j) = A(i,j) for max(1,j-KU)<=i<=min(N,j+kl)
*>
*>          If FACT = 'F' and EQUED is not 'N', then A must have been
*>          equilibrated by the scaling factors in R and/or C.  AB is not
*>          modified if FACT = 'F' or 'N', or if FACT = 'E' and
*>          EQUED = 'N' on exit.
*>
*>          On exit, if EQUED .ne. 'N', A is scaled as follows:
*>          EQUED = 'R':  A := diag(R) * A
*>          EQUED = 'C':  A := A * diag(C)
*>          EQUED = 'B':  A := diag(R) * A * diag(C).
*> \endverbatim
*>
*> \param[in] LDAB
*> \verbatim
*>          LDAB is INTEGER
*>          The leading dimension of the array AB.  LDAB >= KL+KU+1.
*> \endverbatim
*>
*> \param[in,out] AFB
*> \verbatim
*>          AFB is DOUBLE PRECISION array, dimension (LDAFB,N)
*>          If FACT = 'F', then AFB is an input argument and on entry
*>          contains details of the LU factorization of the band matrix
*>          A, as computed by DGBTRF.  U is stored as an upper triangular
*>          band matrix with KL+KU superdiagonals in rows 1 to KL+KU+1,
*>          and the multipliers used during the factorization are stored
*>          in rows KL+KU+2 to 2*KL+KU+1.  If EQUED .ne. 'N', then AFB is
*>          the factored form of the equilibrated matrix A.
*>
*>          If FACT = 'N', then AFB is an output argument and on exit
*>          returns details of the LU factorization of A.
*>
*>          If FACT = 'E', then AFB is an output argument and on exit
*>          returns details of the LU factorization of the equilibrated
*>          matrix A (see the description of AB for the form of the
*>          equilibrated matrix).
*> \endverbatim
*>
*> \param[in] LDAFB
*> \verbatim
*>          LDAFB is INTEGER
*>          The leading dimension of the array AFB.  LDAFB >= 2*KL+KU+1.
*> \endverbatim
*>
*> \param[in,out] IPIV
*> \verbatim
*>          IPIV is INTEGER array, dimension (N)
*>          If FACT = 'F', then IPIV is an input argument and on entry
*>          contains the pivot indices from the factorization A = L*U
*>          as computed by DGBTRF; row i of the matrix was interchanged
*>          with row IPIV(i).
*>
*>          If FACT = 'N', then IPIV is an output argument and on exit
*>          contains the pivot indices from the factorization A = L*U
*>          of the original matrix A.
*>
*>          If FACT = 'E', then IPIV is an output argument and on exit
*>          contains the pivot indices from the factorization A = L*U
*>          of the equilibrated matrix A.
*> \endverbatim
*>
*> \param[in,out] EQUED
*> \verbatim
*>          EQUED is CHARACTER*1
*>          Specifies the form of equilibration that was done.
*>          = 'N':  No equilibration (always true if FACT = 'N').
*>          = 'R':  Row equilibration, i.e., A has been premultiplied by
*>                  diag(R).
*>          = 'C':  Column equilibration, i.e., A has been postmultiplied
*>                  by diag(C).
*>          = 'B':  Both row and column equilibration, i.e., A has been
*>                  replaced by diag(R) * A * diag(C).
*>          EQUED is an input argument if FACT = 'F'; otherwise, it is an
*>          output argument.
*> \endverbatim
*>
*> \param[in,out] R
*> \verbatim
*>          R is DOUBLE PRECISION array, dimension (N)
*>          The row scale factors for A.  If EQUED = 'R' or 'B', A is
*>          multiplied on the left by diag(R); if EQUED = 'N' or 'C', R
*>          is not accessed.  R is an input argument if FACT = 'F';
*>          otherwise, R is an output argument.  If FACT = 'F' and
*>          EQUED = 'R' or 'B', each element of R must be positive.
*> \endverbatim
*>
*> \param[in,out] C
*> \verbatim
*>          C is DOUBLE PRECISION array, dimension (N)
*>          The column scale factors for A.  If EQUED = 'C' or 'B', A is
*>          multiplied on the right by diag(C); if EQUED = 'N' or 'R', C
*>          is not accessed.  C is an input argument if FACT = 'F';
*>          otherwise, C is an output argument.  If FACT = 'F' and
*>          EQUED = 'C' or 'B', each element of C must be positive.
*> \endverbatim
*>
*> \param[in,out] B
*> \verbatim
*>          B is DOUBLE PRECISION array, dimension (LDB,NRHS)
*>          On entry, the right hand side matrix B.
*>          On exit,
*>          if EQUED = 'N', B is not modified;
*>          if TRANS = 'N' and EQUED = 'R' or 'B', B is overwritten by
*>          diag(R)*B;
*>          if TRANS = 'T' or 'C' and EQUED = 'C' or 'B', B is
*>          overwritten by diag(C)*B.
*> \endverbatim
*>
*> \param[in] LDB
*> \verbatim
*>          LDB is INTEGER
*>          The leading dimension of the array B.  LDB >= max(1,N).
*> \endverbatim
*>
*> \param[out] X
*> \verbatim
*>          X is DOUBLE PRECISION array, dimension (LDX,NRHS)
*>          If INFO = 0 or INFO = N+1, the N-by-NRHS solution matrix X
*>          to the original system of equations.  Note that A and B are
*>          modified on exit if EQUED .ne. 'N', and the solution to the
*>          equilibrated system is inv(diag(C))*X if TRANS = 'N' and
*>          EQUED = 'C' or 'B', or inv(diag(R))*X if TRANS = 'T' or 'C'
*>          and EQUED = 'R' or 'B'.
*> \endverbatim
*>
*> \param[in] LDX
*> \verbatim
*>          LDX is INTEGER
*>          The leading dimension of the array X.  LDX >= max(1,N).
*> \endverbatim
*>
*> \param[out] RCOND
*> \verbatim
*>          RCOND is DOUBLE PRECISION
*>          The estimate of the reciprocal condition number of the matrix
*>          A after equilibration (if done).  If RCOND is less than the
*>          machine precision (in particular, if RCOND = 0), the matrix
*>          is singular to working precision.  This condition is
*>          indicated by a return code of INFO > 0.
*> \endverbatim
*>
*> \param[out] FERR
*> \verbatim
*>          FERR is DOUBLE PRECISION array, dimension (NRHS)
*>          The estimated forward error bound for each solution vector
*>          X(j) (the j-th column of the solution matrix X).
*>          If XTRUE is the true solution corresponding to X(j), FERR(j)
*>          is an estimated upper bound for the magnitude of the largest
*>          element in (X(j) - XTRUE) divided by the magnitude of the
*>          largest element in X(j).  The estimate is as reliable as
*>          the estimate for RCOND, and is almost always a slight
*>          overestimate of the true error.
*> \endverbatim
*>
*> \param[out] BERR
*> \verbatim
*>          BERR is DOUBLE PRECISION array, dimension (NRHS)
*>          The componentwise relative backward error of each solution
*>          vector X(j) (i.e., the smallest relative change in
*>          any element of A or B that makes X(j) an exact solution).
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (3*N)
*>          On exit, WORK(1) contains the reciprocal pivot growth
*>          factor norm(A)/norm(U). The "max absolute element" norm is
*>          used. If WORK(1) is much less than 1, then the stability
*>          of the LU factorization of the (equilibrated) matrix A
*>          could be poor. This also means that the solution X, condition
*>          estimator RCOND, and forward error bound FERR could be
*>          unreliable. If factorization fails with 0<INFO<=N, then
*>          WORK(1) contains the reciprocal pivot growth factor for the
*>          leading INFO columns of A.
*> \endverbatim
*>
*> \param[out] IWORK
*> \verbatim
*>          IWORK is INTEGER array, dimension (N)
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value
*>          > 0:  if INFO = i, and i is
*>                <= N:  U(i,i) is exactly zero.  The factorization
*>                       has been completed, but the factor U is exactly
*>                       singular, so the solution and error bounds
*>                       could not be computed. RCOND = 0 is returned.
*>                = N+1: U is nonsingular, but RCOND is less than machine
*>                       precision, meaning that the matrix is singular
*>                       to working precision.  Nevertheless, the
*>                       solution and error bounds are computed because
*>                       there are a number of situations where the
*>                       computed solution can be more accurate than the
*>                       value of RCOND would suggest.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date April 2012
*
*> \ingroup doubleGBsolve
*
*  =====================================================================
      SUBROUTINE DGBSVX( FACT, TRANS, N, KL, KU, NRHS, AB, LDAB, AFB,
     $                   LDAFB, IPIV, EQUED, R, C, B, LDB, X, LDX,
     $                   RCOND, FERR, BERR, WORK, IWORK, INFO )
*
*  -- LAPACK driver routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     April 2012
*
*     .. Scalar Arguments ..
      CHARACTER          EQUED, FACT, TRANS
      INTEGER            INFO, KL, KU, LDAB, LDAFB, LDB, LDX, N, NRHS
      DOUBLE PRECISION   RCOND
*     ..
*     .. Array Arguments ..
      INTEGER            IPIV( * ), IWORK( * )
      DOUBLE PRECISION   AB( LDAB, * ), AFB( LDAFB, * ), B( LDB, * ),
     $                   BERR( * ), C( * ), FERR( * ), R( * ),
     $                   WORK( * ), X( LDX, * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ZERO, ONE
      PARAMETER          ( ZERO = 0.0D+0, ONE = 1.0D+0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            COLEQU, EQUIL, NOFACT, NOTRAN, ROWEQU
      CHARACTER          NORM
      INTEGER            I, INFEQU, J, J1, J2
      DOUBLE PRECISION   AMAX, ANORM, BIGNUM, COLCND, RCMAX, RCMIN,
     $                   ROWCND, RPVGRW, SMLNUM
*     ..
*     .. External Functions ..
      LOGICAL            LSAME
      DOUBLE PRECISION   DLAMCH, DLANGB, DLANTB
      EXTERNAL           LSAME, DLAMCH, DLANGB, DLANTB
*     ..
*     .. External Subroutines ..
      EXTERNAL           DCOPY, DGBCON, DGBEQU, DGBRFS, DGBTRF, DGBTRS,
     $                   DLACPY, DLAQGB, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          ABS, MAX, MIN
*     ..
*     .. Executable Statements ..
*
      INFO = 0
      NOFACT = LSAME( FACT, 'N' )
      EQUIL = LSAME( FACT, 'E' )
      NOTRAN = LSAME( TRANS, 'N' )
      IF( NOFACT .OR. EQUIL ) THEN
         EQUED = 'N'
         ROWEQU = .FALSE.
         COLEQU = .FALSE.
      ELSE
         ROWEQU = LSAME( EQUED, 'R' ) .OR. LSAME( EQUED, 'B' )
         COLEQU = LSAME( EQUED, 'C' ) .OR. LSAME( EQUED, 'B' )
         SMLNUM = DLAMCH( 'Safe minimum' )
         BIGNUM = ONE / SMLNUM
      END IF
*
*     Test the input parameters.
*
      IF( .NOT.NOFACT .AND. .NOT.EQUIL .AND. .NOT.LSAME( FACT, 'F' ) )
     $     THEN
         INFO = -1
      ELSE IF( .NOT.NOTRAN .AND. .NOT.LSAME( TRANS, 'T' ) .AND. .NOT.
     $         LSAME( TRANS, 'C' ) ) THEN
         INFO = -2
      ELSE IF( N.LT.0 ) THEN
         INFO = -3
      ELSE IF( KL.LT.0 ) THEN
         INFO = -4
      ELSE IF( KU.LT.0 ) THEN
         INFO = -5
      ELSE IF( NRHS.LT.0 ) THEN
         INFO = -6
      ELSE IF( LDAB.LT.KL+KU+1 ) THEN
         INFO = -8
      ELSE IF( LDAFB.LT.2*KL+KU+1 ) THEN
         INFO = -10
      ELSE IF( LSAME( FACT, 'F' ) .AND. .NOT.
     $         ( ROWEQU .OR. COLEQU .OR. LSAME( EQUED, 'N' ) ) ) THEN
         INFO = -12
      ELSE
         IF( ROWEQU ) THEN
            RCMIN = BIGNUM
            RCMAX = ZERO
            DO 10 J = 1, N
               RCMIN = MIN( RCMIN, R( J ) )
               RCMAX = MAX( RCMAX, R( J ) )
   10       CONTINUE
            IF( RCMIN.LE.ZERO ) THEN
               INFO = -13
            ELSE IF( N.GT.0 ) THEN
               ROWCND = MAX( RCMIN, SMLNUM ) / MIN( RCMAX, BIGNUM )
            ELSE
               ROWCND = ONE
            END IF
         END IF
         IF( COLEQU .AND. INFO.EQ.0 ) THEN
            RCMIN = BIGNUM
            RCMAX = ZERO
            DO 20 J = 1, N
               RCMIN = MIN( RCMIN, C( J ) )
               RCMAX = MAX( RCMAX, C( J ) )
   20       CONTINUE
            IF( RCMIN.LE.ZERO ) THEN
               INFO = -14
            ELSE IF( N.GT.0 ) THEN
               COLCND = MAX( RCMIN, SMLNUM ) / MIN( RCMAX, BIGNUM )
            ELSE
               COLCND = ONE
            END IF
         END IF
         IF( INFO.EQ.0 ) THEN
            IF( LDB.LT.MAX( 1, N ) ) THEN
               INFO = -16
            ELSE IF( LDX.LT.MAX( 1, N ) ) THEN
               INFO = -18
            END IF
         END IF
      END IF
*
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGBSVX', -INFO )
         RETURN
      END IF
*
      IF( EQUIL ) THEN
*
*        Compute row and column scalings to equilibrate the matrix A.
*
         CALL DGBEQU( N, N, KL, KU, AB, LDAB, R, C, ROWCND, COLCND,
     $                AMAX, INFEQU )
         IF( INFEQU.EQ.0 ) THEN
*
*           Equilibrate the matrix.
*
            CALL DLAQGB( N, N, KL, KU, AB, LDAB, R, C, ROWCND, COLCND,
     $                   AMAX, EQUED )
            ROWEQU = LSAME( EQUED, 'R' ) .OR. LSAME( EQUED, 'B' )
            COLEQU = LSAME( EQUED, 'C' ) .OR. LSAME( EQUED, 'B' )
         END IF
      END IF
*
*     Scale the right hand side.
*
      IF( NOTRAN ) THEN
         IF( ROWEQU ) THEN
            DO 40 J = 1, NRHS
               DO 30 I = 1, N
                  B( I, J ) = R( I )*B( I, J )
   30          CONTINUE
   40       CONTINUE
         END IF
      ELSE IF( COLEQU ) THEN
         DO 60 J = 1, NRHS
            DO 50 I = 1, N
               B( I, J ) = C( I )*B( I, J )
   50       CONTINUE
   60    CONTINUE
      END IF
*
      IF( NOFACT .OR. EQUIL ) THEN
*
*        Compute the LU factorization of the band matrix A.
*
         DO 70 J = 1, N
            J1 = MAX( J-KU, 1 )
            J2 = MIN( J+KL, N )
            CALL DCOPY( J2-J1+1, AB( KU+1-J+J1, J ), 1,
     $                  AFB( KL+KU+1-J+J1, J ), 1 )
   70    CONTINUE
*
         CALL DGBTRF( N, N, KL, KU, AFB, LDAFB, IPIV, INFO )
*
*        Return if INFO is non-zero.
*
         IF( INFO.GT.0 ) THEN
*
*           Compute the reciprocal pivot growth factor of the
*           leading rank-deficient INFO columns of A.
*
            ANORM = ZERO
            DO 90 J = 1, INFO
               DO 80 I = MAX( KU+2-J, 1 ), MIN( N+KU+1-J, KL+KU+1 )
                  ANORM = MAX( ANORM, ABS( AB( I, J ) ) )
   80          CONTINUE
   90       CONTINUE
            RPVGRW = DLANTB( 'M', 'U', 'N', INFO, MIN( INFO-1, KL+KU ),
     $                       AFB( MAX( 1, KL+KU+2-INFO ), 1 ), LDAFB,
     $                       WORK )
            IF( RPVGRW.EQ.ZERO ) THEN
               RPVGRW = ONE
            ELSE
               RPVGRW = ANORM / RPVGRW
            END IF
            WORK( 1 ) = RPVGRW
            RCOND = ZERO
            RETURN
         END IF
      END IF
*
*     Compute the norm of the matrix A and the
*     reciprocal pivot growth factor RPVGRW.
*
      IF( NOTRAN ) THEN
         NORM = '1'
      ELSE
         NORM = 'I'
      END IF
      ANORM = DLANGB( NORM, N, KL, KU, AB, LDAB, WORK )
      RPVGRW = DLANTB( 'M', 'U', 'N', N, KL+KU, AFB, LDAFB, WORK )
      IF( RPVGRW.EQ.ZERO ) THEN
         RPVGRW = ONE
      ELSE
         RPVGRW = DLANGB( 'M', N, KL, KU, AB, LDAB, WORK ) / RPVGRW
      END IF
*
*     Compute the reciprocal of the condition number of A.
*
      CALL DGBCON( NORM, N, KL, KU, AFB, LDAFB, IPIV, ANORM, RCOND,
     $             WORK, IWORK, INFO )
*
*     Compute the solution matrix X.
*
      CALL DLACPY( 'Full', N, NRHS, B, LDB, X, LDX )
      CALL DGBTRS( TRANS, N, KL, KU, NRHS, AFB, LDAFB, IPIV, X, LDX,
     $             INFO )
*
*     Use iterative refinement to improve the computed solution and
*     compute error bounds and backward error estimates for it.
*
      CALL DGBRFS( TRANS, N, KL, KU, NRHS, AB, LDAB, AFB, LDAFB, IPIV,
     $             B, LDB, X, LDX, FERR, BERR, WORK, IWORK, INFO )
*
*     Transform the solution matrix X to a solution of the original
*     system.
*
      IF( NOTRAN ) THEN
         IF( COLEQU ) THEN
            DO 110 J = 1, NRHS
               DO 100 I = 1, N
                  X( I, J ) = C( I )*X( I, J )
  100          CONTINUE
  110       CONTINUE
            DO 120 J = 1, NRHS
               FERR( J ) = FERR( J ) / COLCND
  120       CONTINUE
         END IF
      ELSE IF( ROWEQU ) THEN
         DO 140 J = 1, NRHS
            DO 130 I = 1, N
               X( I, J ) = R( I )*X( I, J )
  130       CONTINUE
  140    CONTINUE
         DO 150 J = 1, NRHS
            FERR( J ) = FERR( J ) / ROWCND
  150    CONTINUE
      END IF
*
*     Set INFO = N+1 if the matrix is singular to working precision.
*
      IF( RCOND.LT.DLAMCH( 'Epsilon' ) )
     $   INFO = N + 1
*
      WORK( 1 ) = RPVGRW
      RETURN
*
*     End of DGBSVX
*
      END
*> \brief \b DGBTF2 computes the LU factorization of a general band matrix using the unblocked version of the algorithm.
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGBTF2 + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgbtf2.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgbtf2.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgbtf2.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGBTF2( M, N, KL, KU, AB, LDAB, IPIV, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, KL, KU, LDAB, M, N
*       ..
*       .. Array Arguments ..
*       INTEGER            IPIV( * )
*       DOUBLE PRECISION   AB( LDAB, * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGBTF2 computes an LU factorization of a real m-by-n band matrix A
*> using partial pivoting with row interchanges.
*>
*> This is the unblocked version of the algorithm, calling Level 2 BLAS.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A.  M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in] KL
*> \verbatim
*>          KL is INTEGER
*>          The number of subdiagonals within the band of A.  KL >= 0.
*> \endverbatim
*>
*> \param[in] KU
*> \verbatim
*>          KU is INTEGER
*>          The number of superdiagonals within the band of A.  KU >= 0.
*> \endverbatim
*>
*> \param[in,out] AB
*> \verbatim
*>          AB is DOUBLE PRECISION array, dimension (LDAB,N)
*>          On entry, the matrix A in band storage, in rows KL+1 to
*>          2*KL+KU+1; rows 1 to KL of the array need not be set.
*>          The j-th column of A is stored in the j-th column of the
*>          array AB as follows:
*>          AB(kl+ku+1+i-j,j) = A(i,j) for max(1,j-ku)<=i<=min(m,j+kl)
*>
*>          On exit, details of the factorization: U is stored as an
*>          upper triangular band matrix with KL+KU superdiagonals in
*>          rows 1 to KL+KU+1, and the multipliers used during the
*>          factorization are stored in rows KL+KU+2 to 2*KL+KU+1.
*>          See below for further details.
*> \endverbatim
*>
*> \param[in] LDAB
*> \verbatim
*>          LDAB is INTEGER
*>          The leading dimension of the array AB.  LDAB >= 2*KL+KU+1.
*> \endverbatim
*>
*> \param[out] IPIV
*> \verbatim
*>          IPIV is INTEGER array, dimension (min(M,N))
*>          The pivot indices; for 1 <= i <= min(M,N), row i of the
*>          matrix was interchanged with row IPIV(i).
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0: successful exit
*>          < 0: if INFO = -i, the i-th argument had an illegal value
*>          > 0: if INFO = +i, U(i,i) is exactly zero. The factorization
*>               has been completed, but the factor U is exactly
*>               singular, and division by zero will occur if it is used
*>               to solve a system of equations.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGBcomputational
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>  The band storage scheme is illustrated by the following example, when
*>  M = N = 6, KL = 2, KU = 1:
*>
*>  On entry:                       On exit:
*>
*>      *    *    *    +    +    +       *    *    *   u14  u25  u36
*>      *    *    +    +    +    +       *    *   u13  u24  u35  u46
*>      *   a12  a23  a34  a45  a56      *   u12  u23  u34  u45  u56
*>     a11  a22  a33  a44  a55  a66     u11  u22  u33  u44  u55  u66
*>     a21  a32  a43  a54  a65   *      m21  m32  m43  m54  m65   *
*>     a31  a42  a53  a64   *    *      m31  m42  m53  m64   *    *
*>
*>  Array elements marked * are not used by the routine; elements marked
*>  + need not be set on entry, but are required by the routine to store
*>  elements of U, because of fill-in resulting from the row
*>  interchanges.
*> \endverbatim
*>
*  =====================================================================
      SUBROUTINE DGBTF2( M, N, KL, KU, AB, LDAB, IPIV, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER            INFO, KL, KU, LDAB, M, N
*     ..
*     .. Array Arguments ..
      INTEGER            IPIV( * )
      DOUBLE PRECISION   AB( LDAB, * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ONE, ZERO
      PARAMETER          ( ONE = 1.0D+0, ZERO = 0.0D+0 )
*     ..
*     .. Local Scalars ..
      INTEGER            I, J, JP, JU, KM, KV
*     ..
*     .. External Functions ..
      INTEGER            IDAMAX
      EXTERNAL           IDAMAX
*     ..
*     .. External Subroutines ..
      EXTERNAL           DGER, DSCAL, DSWAP, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, MIN
*     ..
*     .. Executable Statements ..
*
*     KV is the number of superdiagonals in the factor U, allowing for
*     fill-in.
*
      KV = KU + KL
*
*     Test the input parameters.
*
      INFO = 0
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( KL.LT.0 ) THEN
         INFO = -3
      ELSE IF( KU.LT.0 ) THEN
         INFO = -4
      ELSE IF( LDAB.LT.KL+KV+1 ) THEN
         INFO = -6
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGBTF2', -INFO )
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( M.EQ.0 .OR. N.EQ.0 )
     $   RETURN
*
*     Gaussian elimination with partial pivoting
*
*     Set fill-in elements in columns KU+2 to KV to zero.
*
      DO 20 J = KU + 2, MIN( KV, N )
         DO 10 I = KV - J + 2, KL
            AB( I, J ) = ZERO
   10    CONTINUE
   20 CONTINUE
*
*     JU is the index of the last column affected by the current stage
*     of the factorization.
*
      JU = 1
*
      DO 40 J = 1, MIN( M, N )
*
*        Set fill-in elements in column J+KV to zero.
*
         IF( J+KV.LE.N ) THEN
            DO 30 I = 1, KL
               AB( I, J+KV ) = ZERO
   30       CONTINUE
         END IF
*
*        Find pivot and test for singularity. KM is the number of
*        subdiagonal elements in the current column.
*
         KM = MIN( KL, M-J )
         JP = IDAMAX( KM+1, AB( KV+1, J ), 1 )
         IPIV( J ) = JP + J - 1
         IF( AB( KV+JP, J ).NE.ZERO ) THEN
            JU = MAX( JU, MIN( J+KU+JP-1, N ) )
*
*           Apply interchange to columns J to JU.
*
            IF( JP.NE.1 )
     $         CALL DSWAP( JU-J+1, AB( KV+JP, J ), LDAB-1,
     $                     AB( KV+1, J ), LDAB-1 )
*
            IF( KM.GT.0 ) THEN
*
*              Compute multipliers.
*
               CALL DSCAL( KM, ONE / AB( KV+1, J ), AB( KV+2, J ), 1 )
*
*              Update trailing submatrix within the band.
*
               IF( JU.GT.J )
     $            CALL DGER( KM, JU-J, -ONE, AB( KV+2, J ), 1,
     $                       AB( KV, J+1 ), LDAB-1, AB( KV+1, J+1 ),
     $                       LDAB-1 )
            END IF
         ELSE
*
*           If pivot is zero, set INFO to the index of the pivot
*           unless a zero pivot has already been found.
*
            IF( INFO.EQ.0 )
     $         INFO = J
         END IF
   40 CONTINUE
      RETURN
*
*     End of DGBTF2
*
      END
*> \brief \b DGBTRF
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGBTRF + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgbtrf.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgbtrf.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgbtrf.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGBTRF( M, N, KL, KU, AB, LDAB, IPIV, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, KL, KU, LDAB, M, N
*       ..
*       .. Array Arguments ..
*       INTEGER            IPIV( * )
*       DOUBLE PRECISION   AB( LDAB, * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGBTRF computes an LU factorization of a real m-by-n band matrix A
*> using partial pivoting with row interchanges.
*>
*> This is the blocked version of the algorithm, calling Level 3 BLAS.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A.  M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in] KL
*> \verbatim
*>          KL is INTEGER
*>          The number of subdiagonals within the band of A.  KL >= 0.
*> \endverbatim
*>
*> \param[in] KU
*> \verbatim
*>          KU is INTEGER
*>          The number of superdiagonals within the band of A.  KU >= 0.
*> \endverbatim
*>
*> \param[in,out] AB
*> \verbatim
*>          AB is DOUBLE PRECISION array, dimension (LDAB,N)
*>          On entry, the matrix A in band storage, in rows KL+1 to
*>          2*KL+KU+1; rows 1 to KL of the array need not be set.
*>          The j-th column of A is stored in the j-th column of the
*>          array AB as follows:
*>          AB(kl+ku+1+i-j,j) = A(i,j) for max(1,j-ku)<=i<=min(m,j+kl)
*>
*>          On exit, details of the factorization: U is stored as an
*>          upper triangular band matrix with KL+KU superdiagonals in
*>          rows 1 to KL+KU+1, and the multipliers used during the
*>          factorization are stored in rows KL+KU+2 to 2*KL+KU+1.
*>          See below for further details.
*> \endverbatim
*>
*> \param[in] LDAB
*> \verbatim
*>          LDAB is INTEGER
*>          The leading dimension of the array AB.  LDAB >= 2*KL+KU+1.
*> \endverbatim
*>
*> \param[out] IPIV
*> \verbatim
*>          IPIV is INTEGER array, dimension (min(M,N))
*>          The pivot indices; for 1 <= i <= min(M,N), row i of the
*>          matrix was interchanged with row IPIV(i).
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0: successful exit
*>          < 0: if INFO = -i, the i-th argument had an illegal value
*>          > 0: if INFO = +i, U(i,i) is exactly zero. The factorization
*>               has been completed, but the factor U is exactly
*>               singular, and division by zero will occur if it is used
*>               to solve a system of equations.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGBcomputational
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>  The band storage scheme is illustrated by the following example, when
*>  M = N = 6, KL = 2, KU = 1:
*>
*>  On entry:                       On exit:
*>
*>      *    *    *    +    +    +       *    *    *   u14  u25  u36
*>      *    *    +    +    +    +       *    *   u13  u24  u35  u46
*>      *   a12  a23  a34  a45  a56      *   u12  u23  u34  u45  u56
*>     a11  a22  a33  a44  a55  a66     u11  u22  u33  u44  u55  u66
*>     a21  a32  a43  a54  a65   *      m21  m32  m43  m54  m65   *
*>     a31  a42  a53  a64   *    *      m31  m42  m53  m64   *    *
*>
*>  Array elements marked * are not used by the routine; elements marked
*>  + need not be set on entry, but are required by the routine to store
*>  elements of U because of fill-in resulting from the row interchanges.
*> \endverbatim
*>
*  =====================================================================
      SUBROUTINE DGBTRF( M, N, KL, KU, AB, LDAB, IPIV, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER            INFO, KL, KU, LDAB, M, N
*     ..
*     .. Array Arguments ..
      INTEGER            IPIV( * )
      DOUBLE PRECISION   AB( LDAB, * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ONE, ZERO
      PARAMETER          ( ONE = 1.0D+0, ZERO = 0.0D+0 )
      INTEGER            NBMAX, LDWORK
      PARAMETER          ( NBMAX = 64, LDWORK = NBMAX+1 )
*     ..
*     .. Local Scalars ..
      INTEGER            I, I2, I3, II, IP, J, J2, J3, JB, JJ, JM, JP,
     $                   JU, K2, KM, KV, NB, NW
      DOUBLE PRECISION   TEMP
*     ..
*     .. Local Arrays ..
      DOUBLE PRECISION   WORK13( LDWORK, NBMAX ),
     $                   WORK31( LDWORK, NBMAX )
*     ..
*     .. External Functions ..
      INTEGER            IDAMAX, ILAENV
      EXTERNAL           IDAMAX, ILAENV
*     ..
*     .. External Subroutines ..
      EXTERNAL           DCOPY, DGBTF2, DGEMM, DGER, DLASWP, DSCAL,
     $                   DSWAP, DTRSM, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, MIN
*     ..
*     .. Executable Statements ..
*
*     KV is the number of superdiagonals in the factor U, allowing for
*     fill-in
*
      KV = KU + KL
*
*     Test the input parameters.
*
      INFO = 0
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( KL.LT.0 ) THEN
         INFO = -3
      ELSE IF( KU.LT.0 ) THEN
         INFO = -4
      ELSE IF( LDAB.LT.KL+KV+1 ) THEN
         INFO = -6
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGBTRF', -INFO )
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( M.EQ.0 .OR. N.EQ.0 )
     $   RETURN
*
*     Determine the block size for this environment
*
      NB = ILAENV( 1, 'DGBTRF', ' ', M, N, KL, KU )
*
*     The block size must not exceed the limit set by the size of the
*     local arrays WORK13 and WORK31.
*
      NB = MIN( NB, NBMAX )
*
      IF( NB.LE.1 .OR. NB.GT.KL ) THEN
*
*        Use unblocked code
*
         CALL DGBTF2( M, N, KL, KU, AB, LDAB, IPIV, INFO )
      ELSE
*
*        Use blocked code
*
*        Zero the superdiagonal elements of the work array WORK13
*
         DO 20 J = 1, NB
            DO 10 I = 1, J - 1
               WORK13( I, J ) = ZERO
   10       CONTINUE
   20    CONTINUE
*
*        Zero the subdiagonal elements of the work array WORK31
*
         DO 40 J = 1, NB
            DO 30 I = J + 1, NB
               WORK31( I, J ) = ZERO
   30       CONTINUE
   40    CONTINUE
*
*        Gaussian elimination with partial pivoting
*
*        Set fill-in elements in columns KU+2 to KV to zero
*
         DO 60 J = KU + 2, MIN( KV, N )
            DO 50 I = KV - J + 2, KL
               AB( I, J ) = ZERO
   50       CONTINUE
   60    CONTINUE
*
*        JU is the index of the last column affected by the current
*        stage of the factorization
*
         JU = 1
*
         DO 180 J = 1, MIN( M, N ), NB
            JB = MIN( NB, MIN( M, N )-J+1 )
*
*           The active part of the matrix is partitioned
*
*              A11   A12   A13
*              A21   A22   A23
*              A31   A32   A33
*
*           Here A11, A21 and A31 denote the current block of JB columns
*           which is about to be factorized. The number of rows in the
*           partitioning are JB, I2, I3 respectively, and the numbers
*           of columns are JB, J2, J3. The superdiagonal elements of A13
*           and the subdiagonal elements of A31 lie outside the band.
*
            I2 = MIN( KL-JB, M-J-JB+1 )
            I3 = MIN( JB, M-J-KL+1 )
*
*           J2 and J3 are computed after JU has been updated.
*
*           Factorize the current block of JB columns
*
            DO 80 JJ = J, J + JB - 1
*
*              Set fill-in elements in column JJ+KV to zero
*
               IF( JJ+KV.LE.N ) THEN
                  DO 70 I = 1, KL
                     AB( I, JJ+KV ) = ZERO
   70             CONTINUE
               END IF
*
*              Find pivot and test for singularity. KM is the number of
*              subdiagonal elements in the current column.
*
               KM = MIN( KL, M-JJ )
               JP = IDAMAX( KM+1, AB( KV+1, JJ ), 1 )
               IPIV( JJ ) = JP + JJ - J
               IF( AB( KV+JP, JJ ).NE.ZERO ) THEN
                  JU = MAX( JU, MIN( JJ+KU+JP-1, N ) )
                  IF( JP.NE.1 ) THEN
*
*                    Apply interchange to columns J to J+JB-1
*
                     IF( JP+JJ-1.LT.J+KL ) THEN
*
                        CALL DSWAP( JB, AB( KV+1+JJ-J, J ), LDAB-1,
     $                              AB( KV+JP+JJ-J, J ), LDAB-1 )
                     ELSE
*
*                       The interchange affects columns J to JJ-1 of A31
*                       which are stored in the work array WORK31
*
                        CALL DSWAP( JJ-J, AB( KV+1+JJ-J, J ), LDAB-1,
     $                              WORK31( JP+JJ-J-KL, 1 ), LDWORK )
                        CALL DSWAP( J+JB-JJ, AB( KV+1, JJ ), LDAB-1,
     $                              AB( KV+JP, JJ ), LDAB-1 )
                     END IF
                  END IF
*
*                 Compute multipliers
*
                  CALL DSCAL( KM, ONE / AB( KV+1, JJ ), AB( KV+2, JJ ),
     $                        1 )
*
*                 Update trailing submatrix within the band and within
*                 the current block. JM is the index of the last column
*                 which needs to be updated.
*
                  JM = MIN( JU, J+JB-1 )
                  IF( JM.GT.JJ )
     $               CALL DGER( KM, JM-JJ, -ONE, AB( KV+2, JJ ), 1,
     $                          AB( KV, JJ+1 ), LDAB-1,
     $                          AB( KV+1, JJ+1 ), LDAB-1 )
               ELSE
*
*                 If pivot is zero, set INFO to the index of the pivot
*                 unless a zero pivot has already been found.
*
                  IF( INFO.EQ.0 )
     $               INFO = JJ
               END IF
*
*              Copy current column of A31 into the work array WORK31
*
               NW = MIN( JJ-J+1, I3 )
               IF( NW.GT.0 )
     $            CALL DCOPY( NW, AB( KV+KL+1-JJ+J, JJ ), 1,
     $                        WORK31( 1, JJ-J+1 ), 1 )
   80       CONTINUE
            IF( J+JB.LE.N ) THEN
*
*              Apply the row interchanges to the other blocks.
*
               J2 = MIN( JU-J+1, KV ) - JB
               J3 = MAX( 0, JU-J-KV+1 )
*
*              Use DLASWP to apply the row interchanges to A12, A22, and
*              A32.
*
               CALL DLASWP( J2, AB( KV+1-JB, J+JB ), LDAB-1, 1, JB,
     $                      IPIV( J ), 1 )
*
*              Adjust the pivot indices.
*
               DO 90 I = J, J + JB - 1
                  IPIV( I ) = IPIV( I ) + J - 1
   90          CONTINUE
*
*              Apply the row interchanges to A13, A23, and A33
*              columnwise.
*
               K2 = J - 1 + JB + J2
               DO 110 I = 1, J3
                  JJ = K2 + I
                  DO 100 II = J + I - 1, J + JB - 1
                     IP = IPIV( II )
                     IF( IP.NE.II ) THEN
                        TEMP = AB( KV+1+II-JJ, JJ )
                        AB( KV+1+II-JJ, JJ ) = AB( KV+1+IP-JJ, JJ )
                        AB( KV+1+IP-JJ, JJ ) = TEMP
                     END IF
  100             CONTINUE
  110          CONTINUE
*
*              Update the relevant part of the trailing submatrix
*
               IF( J2.GT.0 ) THEN
*
*                 Update A12
*
                  CALL DTRSM( 'Left', 'Lower', 'No transpose', 'Unit',
     $                        JB, J2, ONE, AB( KV+1, J ), LDAB-1,
     $                        AB( KV+1-JB, J+JB ), LDAB-1 )
*
                  IF( I2.GT.0 ) THEN
*
*                    Update A22
*
                     CALL DGEMM( 'No transpose', 'No transpose', I2, J2,
     $                           JB, -ONE, AB( KV+1+JB, J ), LDAB-1,
     $                           AB( KV+1-JB, J+JB ), LDAB-1, ONE,
     $                           AB( KV+1, J+JB ), LDAB-1 )
                  END IF
*
                  IF( I3.GT.0 ) THEN
*
*                    Update A32
*
                     CALL DGEMM( 'No transpose', 'No transpose', I3, J2,
     $                           JB, -ONE, WORK31, LDWORK,
     $                           AB( KV+1-JB, J+JB ), LDAB-1, ONE,
     $                           AB( KV+KL+1-JB, J+JB ), LDAB-1 )
                  END IF
               END IF
*
               IF( J3.GT.0 ) THEN
*
*                 Copy the lower triangle of A13 into the work array
*                 WORK13
*
                  DO 130 JJ = 1, J3
                     DO 120 II = JJ, JB
                        WORK13( II, JJ ) = AB( II-JJ+1, JJ+J+KV-1 )
  120                CONTINUE
  130             CONTINUE
*
*                 Update A13 in the work array
*
                  CALL DTRSM( 'Left', 'Lower', 'No transpose', 'Unit',
     $                        JB, J3, ONE, AB( KV+1, J ), LDAB-1,
     $                        WORK13, LDWORK )
*
                  IF( I2.GT.0 ) THEN
*
*                    Update A23
*
                     CALL DGEMM( 'No transpose', 'No transpose', I2, J3,
     $                           JB, -ONE, AB( KV+1+JB, J ), LDAB-1,
     $                           WORK13, LDWORK, ONE, AB( 1+JB, J+KV ),
     $                           LDAB-1 )
                  END IF
*
                  IF( I3.GT.0 ) THEN
*
*                    Update A33
*
                     CALL DGEMM( 'No transpose', 'No transpose', I3, J3,
     $                           JB, -ONE, WORK31, LDWORK, WORK13,
     $                           LDWORK, ONE, AB( 1+KL, J+KV ), LDAB-1 )
                  END IF
*
*                 Copy the lower triangle of A13 back into place
*
                  DO 150 JJ = 1, J3
                     DO 140 II = JJ, JB
                        AB( II-JJ+1, JJ+J+KV-1 ) = WORK13( II, JJ )
  140                CONTINUE
  150             CONTINUE
               END IF
            ELSE
*
*              Adjust the pivot indices.
*
               DO 160 I = J, J + JB - 1
                  IPIV( I ) = IPIV( I ) + J - 1
  160          CONTINUE
            END IF
*
*           Partially undo the interchanges in the current block to
*           restore the upper triangular form of A31 and copy the upper
*           triangle of A31 back into place
*
            DO 170 JJ = J + JB - 1, J, -1
               JP = IPIV( JJ ) - JJ + 1
               IF( JP.NE.1 ) THEN
*
*                 Apply interchange to columns J to JJ-1
*
                  IF( JP+JJ-1.LT.J+KL ) THEN
*
*                    The interchange does not affect A31
*
                     CALL DSWAP( JJ-J, AB( KV+1+JJ-J, J ), LDAB-1,
     $                           AB( KV+JP+JJ-J, J ), LDAB-1 )
                  ELSE
*
*                    The interchange does affect A31
*
                     CALL DSWAP( JJ-J, AB( KV+1+JJ-J, J ), LDAB-1,
     $                           WORK31( JP+JJ-J-KL, 1 ), LDWORK )
                  END IF
               END IF
*
*              Copy the current column of A31 back into place
*
               NW = MIN( I3, JJ-J+1 )
               IF( NW.GT.0 )
     $            CALL DCOPY( NW, WORK31( 1, JJ-J+1 ), 1,
     $                        AB( KV+KL+1-JJ+J, JJ ), 1 )
  170       CONTINUE
  180    CONTINUE
      END IF
*
      RETURN
*
*     End of DGBTRF
*
      END
*> \brief \b DGBTRS
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGBTRS + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgbtrs.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgbtrs.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgbtrs.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGBTRS( TRANS, N, KL, KU, NRHS, AB, LDAB, IPIV, B, LDB,
*                          INFO )
*
*       .. Scalar Arguments ..
*       CHARACTER          TRANS
*       INTEGER            INFO, KL, KU, LDAB, LDB, N, NRHS
*       ..
*       .. Array Arguments ..
*       INTEGER            IPIV( * )
*       DOUBLE PRECISION   AB( LDAB, * ), B( LDB, * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGBTRS solves a system of linear equations
*>    A * X = B  or  A**T * X = B
*> with a general band matrix A using the LU factorization computed
*> by DGBTRF.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] TRANS
*> \verbatim
*>          TRANS is CHARACTER*1
*>          Specifies the form of the system of equations.
*>          = 'N':  A * X = B  (No transpose)
*>          = 'T':  A**T* X = B  (Transpose)
*>          = 'C':  A**T* X = B  (Conjugate transpose = Transpose)
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The order of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in] KL
*> \verbatim
*>          KL is INTEGER
*>          The number of subdiagonals within the band of A.  KL >= 0.
*> \endverbatim
*>
*> \param[in] KU
*> \verbatim
*>          KU is INTEGER
*>          The number of superdiagonals within the band of A.  KU >= 0.
*> \endverbatim
*>
*> \param[in] NRHS
*> \verbatim
*>          NRHS is INTEGER
*>          The number of right hand sides, i.e., the number of columns
*>          of the matrix B.  NRHS >= 0.
*> \endverbatim
*>
*> \param[in] AB
*> \verbatim
*>          AB is DOUBLE PRECISION array, dimension (LDAB,N)
*>          Details of the LU factorization of the band matrix A, as
*>          computed by DGBTRF.  U is stored as an upper triangular band
*>          matrix with KL+KU superdiagonals in rows 1 to KL+KU+1, and
*>          the multipliers used during the factorization are stored in
*>          rows KL+KU+2 to 2*KL+KU+1.
*> \endverbatim
*>
*> \param[in] LDAB
*> \verbatim
*>          LDAB is INTEGER
*>          The leading dimension of the array AB.  LDAB >= 2*KL+KU+1.
*> \endverbatim
*>
*> \param[in] IPIV
*> \verbatim
*>          IPIV is INTEGER array, dimension (N)
*>          The pivot indices; for 1 <= i <= N, row i of the matrix was
*>          interchanged with row IPIV(i).
*> \endverbatim
*>
*> \param[in,out] B
*> \verbatim
*>          B is DOUBLE PRECISION array, dimension (LDB,NRHS)
*>          On entry, the right hand side matrix B.
*>          On exit, the solution matrix X.
*> \endverbatim
*>
*> \param[in] LDB
*> \verbatim
*>          LDB is INTEGER
*>          The leading dimension of the array B.  LDB >= max(1,N).
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0: if INFO = -i, the i-th argument had an illegal value
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGBcomputational
*
*  =====================================================================
      SUBROUTINE DGBTRS( TRANS, N, KL, KU, NRHS, AB, LDAB, IPIV, B, LDB,
     $                   INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      CHARACTER          TRANS
      INTEGER            INFO, KL, KU, LDAB, LDB, N, NRHS
*     ..
*     .. Array Arguments ..
      INTEGER            IPIV( * )
      DOUBLE PRECISION   AB( LDAB, * ), B( LDB, * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ONE
      PARAMETER          ( ONE = 1.0D+0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            LNOTI, NOTRAN
      INTEGER            I, J, KD, L, LM
*     ..
*     .. External Functions ..
      LOGICAL            LSAME
      EXTERNAL           LSAME
*     ..
*     .. External Subroutines ..
      EXTERNAL           DGEMV, DGER, DSWAP, DTBSV, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, MIN
*     ..
*     .. Executable Statements ..
*
*     Test the input parameters.
*
      INFO = 0
      NOTRAN = LSAME( TRANS, 'N' )
      IF( .NOT.NOTRAN .AND. .NOT.LSAME( TRANS, 'T' ) .AND. .NOT.
     $    LSAME( TRANS, 'C' ) ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( KL.LT.0 ) THEN
         INFO = -3
      ELSE IF( KU.LT.0 ) THEN
         INFO = -4
      ELSE IF( NRHS.LT.0 ) THEN
         INFO = -5
      ELSE IF( LDAB.LT.( 2*KL+KU+1 ) ) THEN
         INFO = -7
      ELSE IF( LDB.LT.MAX( 1, N ) ) THEN
         INFO = -10
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGBTRS', -INFO )
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( N.EQ.0 .OR. NRHS.EQ.0 )
     $   RETURN
*
      KD = KU + KL + 1
      LNOTI = KL.GT.0
*
      IF( NOTRAN ) THEN
*
*        Solve  A*X = B.
*
*        Solve L*X = B, overwriting B with X.
*
*        L is represented as a product of permutations and unit lower
*        triangular matrices L = P(1) * L(1) * ... * P(n-1) * L(n-1),
*        where each transformation L(i) is a rank-one modification of
*        the identity matrix.
*
         IF( LNOTI ) THEN
            DO 10 J = 1, N - 1
               LM = MIN( KL, N-J )
               L = IPIV( J )
               IF( L.NE.J )
     $            CALL DSWAP( NRHS, B( L, 1 ), LDB, B( J, 1 ), LDB )
               CALL DGER( LM, NRHS, -ONE, AB( KD+1, J ), 1, B( J, 1 ),
     $                    LDB, B( J+1, 1 ), LDB )
   10       CONTINUE
         END IF
*
         DO 20 I = 1, NRHS
*
*           Solve U*X = B, overwriting B with X.
*
            CALL DTBSV( 'Upper', 'No transpose', 'Non-unit', N, KL+KU,
     $                  AB, LDAB, B( 1, I ), 1 )
   20    CONTINUE
*
      ELSE
*
*        Solve A**T*X = B.
*
         DO 30 I = 1, NRHS
*
*           Solve U**T*X = B, overwriting B with X.
*
            CALL DTBSV( 'Upper', 'Transpose', 'Non-unit', N, KL+KU, AB,
     $                  LDAB, B( 1, I ), 1 )
   30    CONTINUE
*
*        Solve L**T*X = B, overwriting B with X.
*
         IF( LNOTI ) THEN
            DO 40 J = N - 1, 1, -1
               LM = MIN( KL, N-J )
               CALL DGEMV( 'Transpose', LM, NRHS, -ONE, B( J+1, 1 ),
     $                     LDB, AB( KD+1, J ), 1, ONE, B( J, 1 ), LDB )
               L = IPIV( J )
               IF( L.NE.J )
     $            CALL DSWAP( NRHS, B( L, 1 ), LDB, B( J, 1 ), LDB )
   40       CONTINUE
         END IF
      END IF
      RETURN
*
*     End of DGBTRS
*
      END
*> \brief \b DGEBAK
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGEBAK + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgebak.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgebak.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgebak.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGEBAK( JOB, SIDE, N, ILO, IHI, SCALE, M, V, LDV,
*                          INFO )
*
*       .. Scalar Arguments ..
*       CHARACTER          JOB, SIDE
*       INTEGER            IHI, ILO, INFO, LDV, M, N
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   SCALE( * ), V( LDV, * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGEBAK forms the right or left eigenvectors of a real general matrix
*> by backward transformation on the computed eigenvectors of the
*> balanced matrix output by DGEBAL.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] JOB
*> \verbatim
*>          JOB is CHARACTER*1
*>          Specifies the type of backward transformation required:
*>          = 'N', do nothing, return immediately;
*>          = 'P', do backward transformation for permutation only;
*>          = 'S', do backward transformation for scaling only;
*>          = 'B', do backward transformations for both permutation and
*>                 scaling.
*>          JOB must be the same as the argument JOB supplied to DGEBAL.
*> \endverbatim
*>
*> \param[in] SIDE
*> \verbatim
*>          SIDE is CHARACTER*1
*>          = 'R':  V contains right eigenvectors;
*>          = 'L':  V contains left eigenvectors.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of rows of the matrix V.  N >= 0.
*> \endverbatim
*>
*> \param[in] ILO
*> \verbatim
*>          ILO is INTEGER
*> \endverbatim
*>
*> \param[in] IHI
*> \verbatim
*>          IHI is INTEGER
*>          The integers ILO and IHI determined by DGEBAL.
*>          1 <= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0.
*> \endverbatim
*>
*> \param[in] SCALE
*> \verbatim
*>          SCALE is DOUBLE PRECISION array, dimension (N)
*>          Details of the permutation and scaling factors, as returned
*>          by DGEBAL.
*> \endverbatim
*>
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of columns of the matrix V.  M >= 0.
*> \endverbatim
*>
*> \param[in,out] V
*> \verbatim
*>          V is DOUBLE PRECISION array, dimension (LDV,M)
*>          On entry, the matrix of right or left eigenvectors to be
*>          transformed, as returned by DHSEIN or DTREVC.
*>          On exit, V is overwritten by the transformed eigenvectors.
*> \endverbatim
*>
*> \param[in] LDV
*> \verbatim
*>          LDV is INTEGER
*>          The leading dimension of the array V. LDV >= max(1,N).
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEcomputational
*
*  =====================================================================
      SUBROUTINE DGEBAK( JOB, SIDE, N, ILO, IHI, SCALE, M, V, LDV,
     $                   INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      CHARACTER          JOB, SIDE
      INTEGER            IHI, ILO, INFO, LDV, M, N
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   SCALE( * ), V( LDV, * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ONE
      PARAMETER          ( ONE = 1.0D+0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            LEFTV, RIGHTV
      INTEGER            I, II, K
      DOUBLE PRECISION   S
*     ..
*     .. External Functions ..
      LOGICAL            LSAME
      EXTERNAL           LSAME
*     ..
*     .. External Subroutines ..
      EXTERNAL           DSCAL, DSWAP, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, MIN
*     ..
*     .. Executable Statements ..
*
*     Decode and Test the input parameters
*
      RIGHTV = LSAME( SIDE, 'R' )
      LEFTV = LSAME( SIDE, 'L' )
*
      INFO = 0
      IF( .NOT.LSAME( JOB, 'N' ) .AND. .NOT.LSAME( JOB, 'P' ) .AND.
     $    .NOT.LSAME( JOB, 'S' ) .AND. .NOT.LSAME( JOB, 'B' ) ) THEN
         INFO = -1
      ELSE IF( .NOT.RIGHTV .AND. .NOT.LEFTV ) THEN
         INFO = -2
      ELSE IF( N.LT.0 ) THEN
         INFO = -3
      ELSE IF( ILO.LT.1 .OR. ILO.GT.MAX( 1, N ) ) THEN
         INFO = -4
      ELSE IF( IHI.LT.MIN( ILO, N ) .OR. IHI.GT.N ) THEN
         INFO = -5
      ELSE IF( M.LT.0 ) THEN
         INFO = -7
      ELSE IF( LDV.LT.MAX( 1, N ) ) THEN
         INFO = -9
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGEBAK', -INFO )
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( N.EQ.0 )
     $   RETURN
      IF( M.EQ.0 )
     $   RETURN
      IF( LSAME( JOB, 'N' ) )
     $   RETURN
*
      IF( ILO.EQ.IHI )
     $   GO TO 30
*
*     Backward balance
*
      IF( LSAME( JOB, 'S' ) .OR. LSAME( JOB, 'B' ) ) THEN
*
         IF( RIGHTV ) THEN
            DO 10 I = ILO, IHI
               S = SCALE( I )
               CALL DSCAL( M, S, V( I, 1 ), LDV )
   10       CONTINUE
         END IF
*
         IF( LEFTV ) THEN
            DO 20 I = ILO, IHI
               S = ONE / SCALE( I )
               CALL DSCAL( M, S, V( I, 1 ), LDV )
   20       CONTINUE
         END IF
*
      END IF
*
*     Backward permutation
*
*     For  I = ILO-1 step -1 until 1,
*              IHI+1 step 1 until N do --
*
   30 CONTINUE
      IF( LSAME( JOB, 'P' ) .OR. LSAME( JOB, 'B' ) ) THEN
         IF( RIGHTV ) THEN
            DO 40 II = 1, N
               I = II
               IF( I.GE.ILO .AND. I.LE.IHI )
     $            GO TO 40
               IF( I.LT.ILO )
     $            I = ILO - II
               K = SCALE( I )
               IF( K.EQ.I )
     $            GO TO 40
               CALL DSWAP( M, V( I, 1 ), LDV, V( K, 1 ), LDV )
   40       CONTINUE
         END IF
*
         IF( LEFTV ) THEN
            DO 50 II = 1, N
               I = II
               IF( I.GE.ILO .AND. I.LE.IHI )
     $            GO TO 50
               IF( I.LT.ILO )
     $            I = ILO - II
               K = SCALE( I )
               IF( K.EQ.I )
     $            GO TO 50
               CALL DSWAP( M, V( I, 1 ), LDV, V( K, 1 ), LDV )
   50       CONTINUE
         END IF
      END IF
*
      RETURN
*
*     End of DGEBAK
*
      END
*> \brief \b DGEBAL
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGEBAL + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgebal.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgebal.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgebal.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGEBAL( JOB, N, A, LDA, ILO, IHI, SCALE, INFO )
*
*       .. Scalar Arguments ..
*       CHARACTER          JOB
*       INTEGER            IHI, ILO, INFO, LDA, N
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   A( LDA, * ), SCALE( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGEBAL balances a general real matrix A.  This involves, first,
*> permuting A by a similarity transformation to isolate eigenvalues
*> in the first 1 to ILO-1 and last IHI+1 to N elements on the
*> diagonal; and second, applying a diagonal similarity transformation
*> to rows and columns ILO to IHI to make the rows and columns as
*> close in norm as possible.  Both steps are optional.
*>
*> Balancing may reduce the 1-norm of the matrix, and improve the
*> accuracy of the computed eigenvalues and/or eigenvectors.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] JOB
*> \verbatim
*>          JOB is CHARACTER*1
*>          Specifies the operations to be performed on A:
*>          = 'N':  none:  simply set ILO = 1, IHI = N, SCALE(I) = 1.0
*>                  for i = 1,...,N;
*>          = 'P':  permute only;
*>          = 'S':  scale only;
*>          = 'B':  both permute and scale.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The order of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the input matrix A.
*>          On exit,  A is overwritten by the balanced matrix.
*>          If JOB = 'N', A is not referenced.
*>          See Further Details.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,N).
*> \endverbatim
*>
*> \param[out] ILO
*> \verbatim
*>          ILO is INTEGER
*> \endverbatim
*> \param[out] IHI
*> \verbatim
*>          IHI is INTEGER
*>          ILO and IHI are set to integers such that on exit
*>          A(i,j) = 0 if i > j and j = 1,...,ILO-1 or I = IHI+1,...,N.
*>          If JOB = 'N' or 'S', ILO = 1 and IHI = N.
*> \endverbatim
*>
*> \param[out] SCALE
*> \verbatim
*>          SCALE is DOUBLE PRECISION array, dimension (N)
*>          Details of the permutations and scaling factors applied to
*>          A.  If P(j) is the index of the row and column interchanged
*>          with row and column j and D(j) is the scaling factor
*>          applied to row and column j, then
*>          SCALE(j) = P(j)    for j = 1,...,ILO-1
*>                   = D(j)    for j = ILO,...,IHI
*>                   = P(j)    for j = IHI+1,...,N.
*>          The order in which the interchanges are made is N to IHI+1,
*>          then 1 to ILO-1.
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit.
*>          < 0:  if INFO = -i, the i-th argument had an illegal value.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date June 2017
*
*> \ingroup doubleGEcomputational
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>  The permutations consist of row and column interchanges which put
*>  the matrix in the form
*>
*>             ( T1   X   Y  )
*>     P A P = (  0   B   Z  )
*>             (  0   0   T2 )
*>
*>  where T1 and T2 are upper triangular matrices whose eigenvalues lie
*>  along the diagonal.  The column indices ILO and IHI mark the starting
*>  and ending columns of the submatrix B. Balancing consists of applying
*>  a diagonal similarity transformation inv(D) * B * D to make the
*>  1-norms of each row of B and its corresponding column nearly equal.
*>  The output matrix is
*>
*>     ( T1     X*D          Y    )
*>     (  0  inv(D)*B*D  inv(D)*Z ).
*>     (  0      0           T2   )
*>
*>  Information about the permutations P and the diagonal matrix D is
*>  returned in the vector SCALE.
*>
*>  This subroutine is based on the EISPACK routine BALANC.
*>
*>  Modified by Tzu-Yi Chen, Computer Science Division, University of
*>    California at Berkeley, USA
*> \endverbatim
*>
*  =====================================================================
      SUBROUTINE DGEBAL( JOB, N, A, LDA, ILO, IHI, SCALE, INFO )
*
*  -- LAPACK computational routine (version 3.7.1) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     June 2017
*
*     .. Scalar Arguments ..
      CHARACTER          JOB
      INTEGER            IHI, ILO, INFO, LDA, N
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   A( LDA, * ), SCALE( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ZERO, ONE
      PARAMETER          ( ZERO = 0.0D+0, ONE = 1.0D+0 )
      DOUBLE PRECISION   SCLFAC
      PARAMETER          ( SCLFAC = 2.0D+0 )
      DOUBLE PRECISION   FACTOR
      PARAMETER          ( FACTOR = 0.95D+0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            NOCONV
      INTEGER            I, ICA, IEXC, IRA, J, K, L, M
      DOUBLE PRECISION   C, CA, F, G, R, RA, S, SFMAX1, SFMAX2, SFMIN1,
     $                   SFMIN2
*     ..
*     .. External Functions ..
      LOGICAL            DISNAN, LSAME
      INTEGER            IDAMAX
      DOUBLE PRECISION   DLAMCH, DNRM2
      EXTERNAL           DISNAN, LSAME, IDAMAX, DLAMCH, DNRM2
*     ..
*     .. External Subroutines ..
      EXTERNAL           DSCAL, DSWAP, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          ABS, MAX, MIN
*     ..
*     Test the input parameters
*
      INFO = 0
      IF( .NOT.LSAME( JOB, 'N' ) .AND. .NOT.LSAME( JOB, 'P' ) .AND.
     $    .NOT.LSAME( JOB, 'S' ) .AND. .NOT.LSAME( JOB, 'B' ) ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
         INFO = -4
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGEBAL', -INFO )
         RETURN
      END IF
*
      K = 1
      L = N
*
      IF( N.EQ.0 )
     $   GO TO 210
*
      IF( LSAME( JOB, 'N' ) ) THEN
         DO 10 I = 1, N
            SCALE( I ) = ONE
   10    CONTINUE
         GO TO 210
      END IF
*
      IF( LSAME( JOB, 'S' ) )
     $   GO TO 120
*
*     Permutation to isolate eigenvalues if possible
*
      GO TO 50
*
*     Row and column exchange.
*
   20 CONTINUE
      SCALE( M ) = J
      IF( J.EQ.M )
     $   GO TO 30
*
      CALL DSWAP( L, A( 1, J ), 1, A( 1, M ), 1 )
      CALL DSWAP( N-K+1, A( J, K ), LDA, A( M, K ), LDA )
*
   30 CONTINUE
      GO TO ( 40, 80 )IEXC
*
*     Search for rows isolating an eigenvalue and push them down.
*
   40 CONTINUE
      IF( L.EQ.1 )
     $   GO TO 210
      L = L - 1
*
   50 CONTINUE
      DO 70 J = L, 1, -1
*
         DO 60 I = 1, L
            IF( I.EQ.J )
     $         GO TO 60
            IF( A( J, I ).NE.ZERO )
     $         GO TO 70
   60    CONTINUE
*
         M = L
         IEXC = 1
         GO TO 20
   70 CONTINUE
*
      GO TO 90
*
*     Search for columns isolating an eigenvalue and push them left.
*
   80 CONTINUE
      K = K + 1
*
   90 CONTINUE
      DO 110 J = K, L
*
         DO 100 I = K, L
            IF( I.EQ.J )
     $         GO TO 100
            IF( A( I, J ).NE.ZERO )
     $         GO TO 110
  100    CONTINUE
*
         M = K
         IEXC = 2
         GO TO 20
  110 CONTINUE
*
  120 CONTINUE
      DO 130 I = K, L
         SCALE( I ) = ONE
  130 CONTINUE
*
      IF( LSAME( JOB, 'P' ) )
     $   GO TO 210
*
*     Balance the submatrix in rows K to L.
*
*     Iterative loop for norm reduction
*
      SFMIN1 = DLAMCH( 'S' ) / DLAMCH( 'P' )
      SFMAX1 = ONE / SFMIN1
      SFMIN2 = SFMIN1*SCLFAC
      SFMAX2 = ONE / SFMIN2
*
  140 CONTINUE
      NOCONV = .FALSE.
*
      DO 200 I = K, L
*
         C = DNRM2( L-K+1, A( K, I ), 1 )
         R = DNRM2( L-K+1, A( I, K ), LDA )
         ICA = IDAMAX( L, A( 1, I ), 1 )
         CA = ABS( A( ICA, I ) )
         IRA = IDAMAX( N-K+1, A( I, K ), LDA )
         RA = ABS( A( I, IRA+K-1 ) )
*
*        Guard against zero C or R due to underflow.
*
         IF( C.EQ.ZERO .OR. R.EQ.ZERO )
     $      GO TO 200
         G = R / SCLFAC
         F = ONE
         S = C + R
  160    CONTINUE
         IF( C.GE.G .OR. MAX( F, C, CA ).GE.SFMAX2 .OR.
     $       MIN( R, G, RA ).LE.SFMIN2 )GO TO 170
            IF( DISNAN( C+F+CA+R+G+RA ) ) THEN
*
*           Exit if NaN to avoid infinite loop
*
            INFO = -3
            CALL XERBLA( 'DGEBAL', -INFO )
            RETURN
         END IF
         F = F*SCLFAC
         C = C*SCLFAC
         CA = CA*SCLFAC
         R = R / SCLFAC
         G = G / SCLFAC
         RA = RA / SCLFAC
         GO TO 160
*
  170    CONTINUE
         G = C / SCLFAC
  180    CONTINUE
         IF( G.LT.R .OR. MAX( R, RA ).GE.SFMAX2 .OR.
     $       MIN( F, C, G, CA ).LE.SFMIN2 )GO TO 190
         F = F / SCLFAC
         C = C / SCLFAC
         G = G / SCLFAC
         CA = CA / SCLFAC
         R = R*SCLFAC
         RA = RA*SCLFAC
         GO TO 180
*
*        Now balance.
*
  190    CONTINUE
         IF( ( C+R ).GE.FACTOR*S )
     $      GO TO 200
         IF( F.LT.ONE .AND. SCALE( I ).LT.ONE ) THEN
            IF( F*SCALE( I ).LE.SFMIN1 )
     $         GO TO 200
         END IF
         IF( F.GT.ONE .AND. SCALE( I ).GT.ONE ) THEN
            IF( SCALE( I ).GE.SFMAX1 / F )
     $         GO TO 200
         END IF
         G = ONE / F
         SCALE( I ) = SCALE( I )*F
         NOCONV = .TRUE.
*
         CALL DSCAL( N-K+1, G, A( I, K ), LDA )
         CALL DSCAL( L, F, A( 1, I ), 1 )
*
  200 CONTINUE
*
      IF( NOCONV )
     $   GO TO 140
*
  210 CONTINUE
      ILO = K
      IHI = L
*
      RETURN
*
*     End of DGEBAL
*
      END
*> \brief \b DGEBD2 reduces a general matrix to bidiagonal form using an unblocked algorithm.
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGEBD2 + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgebd2.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgebd2.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgebd2.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGEBD2( M, N, A, LDA, D, E, TAUQ, TAUP, WORK, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, LDA, M, N
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   A( LDA, * ), D( * ), E( * ), TAUP( * ),
*      $                   TAUQ( * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGEBD2 reduces a real general m by n matrix A to upper or lower
*> bidiagonal form B by an orthogonal transformation: Q**T * A * P = B.
*>
*> If m >= n, B is upper bidiagonal; if m < n, B is lower bidiagonal.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows in the matrix A.  M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns in the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the m by n general matrix to be reduced.
*>          On exit,
*>          if m >= n, the diagonal and the first superdiagonal are
*>            overwritten with the upper bidiagonal matrix B; the
*>            elements below the diagonal, with the array TAUQ, represent
*>            the orthogonal matrix Q as a product of elementary
*>            reflectors, and the elements above the first superdiagonal,
*>            with the array TAUP, represent the orthogonal matrix P as
*>            a product of elementary reflectors;
*>          if m < n, the diagonal and the first subdiagonal are
*>            overwritten with the lower bidiagonal matrix B; the
*>            elements below the first subdiagonal, with the array TAUQ,
*>            represent the orthogonal matrix Q as a product of
*>            elementary reflectors, and the elements above the diagonal,
*>            with the array TAUP, represent the orthogonal matrix P as
*>            a product of elementary reflectors.
*>          See Further Details.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,M).
*> \endverbatim
*>
*> \param[out] D
*> \verbatim
*>          D is DOUBLE PRECISION array, dimension (min(M,N))
*>          The diagonal elements of the bidiagonal matrix B:
*>          D(i) = A(i,i).
*> \endverbatim
*>
*> \param[out] E
*> \verbatim
*>          E is DOUBLE PRECISION array, dimension (min(M,N)-1)
*>          The off-diagonal elements of the bidiagonal matrix B:
*>          if m >= n, E(i) = A(i,i+1) for i = 1,2,...,n-1;
*>          if m < n, E(i) = A(i+1,i) for i = 1,2,...,m-1.
*> \endverbatim
*>
*> \param[out] TAUQ
*> \verbatim
*>          TAUQ is DOUBLE PRECISION array, dimension (min(M,N))
*>          The scalar factors of the elementary reflectors which
*>          represent the orthogonal matrix Q. See Further Details.
*> \endverbatim
*>
*> \param[out] TAUP
*> \verbatim
*>          TAUP is DOUBLE PRECISION array, dimension (min(M,N))
*>          The scalar factors of the elementary reflectors which
*>          represent the orthogonal matrix P. See Further Details.
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (max(M,N))
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0: successful exit.
*>          < 0: if INFO = -i, the i-th argument had an illegal value.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date June 2017
*
*> \ingroup doubleGEcomputational
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>  The matrices Q and P are represented as products of elementary
*>  reflectors:
*>
*>  If m >= n,
*>
*>     Q = H(1) H(2) . . . H(n)  and  P = G(1) G(2) . . . G(n-1)
*>
*>  Each H(i) and G(i) has the form:
*>
*>     H(i) = I - tauq * v * v**T  and G(i) = I - taup * u * u**T
*>
*>  where tauq and taup are real scalars, and v and u are real vectors;
*>  v(1:i-1) = 0, v(i) = 1, and v(i+1:m) is stored on exit in A(i+1:m,i);
*>  u(1:i) = 0, u(i+1) = 1, and u(i+2:n) is stored on exit in A(i,i+2:n);
*>  tauq is stored in TAUQ(i) and taup in TAUP(i).
*>
*>  If m < n,
*>
*>     Q = H(1) H(2) . . . H(m-1)  and  P = G(1) G(2) . . . G(m)
*>
*>  Each H(i) and G(i) has the form:
*>
*>     H(i) = I - tauq * v * v**T  and G(i) = I - taup * u * u**T
*>
*>  where tauq and taup are real scalars, and v and u are real vectors;
*>  v(1:i) = 0, v(i+1) = 1, and v(i+2:m) is stored on exit in A(i+2:m,i);
*>  u(1:i-1) = 0, u(i) = 1, and u(i+1:n) is stored on exit in A(i,i+1:n);
*>  tauq is stored in TAUQ(i) and taup in TAUP(i).
*>
*>  The contents of A on exit are illustrated by the following examples:
*>
*>  m = 6 and n = 5 (m > n):          m = 5 and n = 6 (m < n):
*>
*>    (  d   e   u1  u1  u1 )           (  d   u1  u1  u1  u1  u1 )
*>    (  v1  d   e   u2  u2 )           (  e   d   u2  u2  u2  u2 )
*>    (  v1  v2  d   e   u3 )           (  v1  e   d   u3  u3  u3 )
*>    (  v1  v2  v3  d   e  )           (  v1  v2  e   d   u4  u4 )
*>    (  v1  v2  v3  v4  d  )           (  v1  v2  v3  e   d   u5 )
*>    (  v1  v2  v3  v4  v5 )
*>
*>  where d and e denote diagonal and off-diagonal elements of B, vi
*>  denotes an element of the vector defining H(i), and ui an element of
*>  the vector defining G(i).
*> \endverbatim
*>
*  =====================================================================
      SUBROUTINE DGEBD2( M, N, A, LDA, D, E, TAUQ, TAUP, WORK, INFO )
*
*  -- LAPACK computational routine (version 3.7.1) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     June 2017
*
*     .. Scalar Arguments ..
      INTEGER            INFO, LDA, M, N
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   A( LDA, * ), D( * ), E( * ), TAUP( * ),
     $                   TAUQ( * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ZERO, ONE
      PARAMETER          ( ZERO = 0.0D+0, ONE = 1.0D+0 )
*     ..
*     .. Local Scalars ..
      INTEGER            I
*     ..
*     .. External Subroutines ..
      EXTERNAL           DLARF, DLARFG, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, MIN
*     ..
*     .. Executable Statements ..
*
*     Test the input parameters
*
      INFO = 0
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -4
      END IF
      IF( INFO.LT.0 ) THEN
         CALL XERBLA( 'DGEBD2', -INFO )
         RETURN
      END IF
*
      IF( M.GE.N ) THEN
*
*        Reduce to upper bidiagonal form
*
         DO 10 I = 1, N
*
*           Generate elementary reflector H(i) to annihilate A(i+1:m,i)
*
            CALL DLARFG( M-I+1, A( I, I ), A( MIN( I+1, M ), I ), 1,
     $                   TAUQ( I ) )
            D( I ) = A( I, I )
            A( I, I ) = ONE
*
*           Apply H(i) to A(i:m,i+1:n) from the left
*
            IF( I.LT.N )
     $         CALL DLARF( 'Left', M-I+1, N-I, A( I, I ), 1, TAUQ( I ),
     $                     A( I, I+1 ), LDA, WORK )
            A( I, I ) = D( I )
*
            IF( I.LT.N ) THEN
*
*              Generate elementary reflector G(i) to annihilate
*              A(i,i+2:n)
*
               CALL DLARFG( N-I, A( I, I+1 ), A( I, MIN( I+2, N ) ),
     $                      LDA, TAUP( I ) )
               E( I ) = A( I, I+1 )
               A( I, I+1 ) = ONE
*
*              Apply G(i) to A(i+1:m,i+1:n) from the right
*
               CALL DLARF( 'Right', M-I, N-I, A( I, I+1 ), LDA,
     $                     TAUP( I ), A( I+1, I+1 ), LDA, WORK )
               A( I, I+1 ) = E( I )
            ELSE
               TAUP( I ) = ZERO
            END IF
   10    CONTINUE
      ELSE
*
*        Reduce to lower bidiagonal form
*
         DO 20 I = 1, M
*
*           Generate elementary reflector G(i) to annihilate A(i,i+1:n)
*
            CALL DLARFG( N-I+1, A( I, I ), A( I, MIN( I+1, N ) ), LDA,
     $                   TAUP( I ) )
            D( I ) = A( I, I )
            A( I, I ) = ONE
*
*           Apply G(i) to A(i+1:m,i:n) from the right
*
            IF( I.LT.M )
     $         CALL DLARF( 'Right', M-I, N-I+1, A( I, I ), LDA,
     $                     TAUP( I ), A( I+1, I ), LDA, WORK )
            A( I, I ) = D( I )
*
            IF( I.LT.M ) THEN
*
*              Generate elementary reflector H(i) to annihilate
*              A(i+2:m,i)
*
               CALL DLARFG( M-I, A( I+1, I ), A( MIN( I+2, M ), I ), 1,
     $                      TAUQ( I ) )
               E( I ) = A( I+1, I )
               A( I+1, I ) = ONE
*
*              Apply H(i) to A(i+1:m,i+1:n) from the left
*
               CALL DLARF( 'Left', M-I, N-I, A( I+1, I ), 1, TAUQ( I ),
     $                     A( I+1, I+1 ), LDA, WORK )
               A( I+1, I ) = E( I )
            ELSE
               TAUQ( I ) = ZERO
            END IF
   20    CONTINUE
      END IF
      RETURN
*
*     End of DGEBD2
*
      END
*> \brief \b DGEBRD
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGEBRD + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgebrd.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgebrd.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgebrd.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGEBRD( M, N, A, LDA, D, E, TAUQ, TAUP, WORK, LWORK,
*                          INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, LDA, LWORK, M, N
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   A( LDA, * ), D( * ), E( * ), TAUP( * ),
*      $                   TAUQ( * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGEBRD reduces a general real M-by-N matrix A to upper or lower
*> bidiagonal form B by an orthogonal transformation: Q**T * A * P = B.
*>
*> If m >= n, B is upper bidiagonal; if m < n, B is lower bidiagonal.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows in the matrix A.  M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns in the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the M-by-N general matrix to be reduced.
*>          On exit,
*>          if m >= n, the diagonal and the first superdiagonal are
*>            overwritten with the upper bidiagonal matrix B; the
*>            elements below the diagonal, with the array TAUQ, represent
*>            the orthogonal matrix Q as a product of elementary
*>            reflectors, and the elements above the first superdiagonal,
*>            with the array TAUP, represent the orthogonal matrix P as
*>            a product of elementary reflectors;
*>          if m < n, the diagonal and the first subdiagonal are
*>            overwritten with the lower bidiagonal matrix B; the
*>            elements below the first subdiagonal, with the array TAUQ,
*>            represent the orthogonal matrix Q as a product of
*>            elementary reflectors, and the elements above the diagonal,
*>            with the array TAUP, represent the orthogonal matrix P as
*>            a product of elementary reflectors.
*>          See Further Details.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,M).
*> \endverbatim
*>
*> \param[out] D
*> \verbatim
*>          D is DOUBLE PRECISION array, dimension (min(M,N))
*>          The diagonal elements of the bidiagonal matrix B:
*>          D(i) = A(i,i).
*> \endverbatim
*>
*> \param[out] E
*> \verbatim
*>          E is DOUBLE PRECISION array, dimension (min(M,N)-1)
*>          The off-diagonal elements of the bidiagonal matrix B:
*>          if m >= n, E(i) = A(i,i+1) for i = 1,2,...,n-1;
*>          if m < n, E(i) = A(i+1,i) for i = 1,2,...,m-1.
*> \endverbatim
*>
*> \param[out] TAUQ
*> \verbatim
*>          TAUQ is DOUBLE PRECISION array, dimension (min(M,N))
*>          The scalar factors of the elementary reflectors which
*>          represent the orthogonal matrix Q. See Further Details.
*> \endverbatim
*>
*> \param[out] TAUP
*> \verbatim
*>          TAUP is DOUBLE PRECISION array, dimension (min(M,N))
*>          The scalar factors of the elementary reflectors which
*>          represent the orthogonal matrix P. See Further Details.
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK))
*>          On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
*> \endverbatim
*>
*> \param[in] LWORK
*> \verbatim
*>          LWORK is INTEGER
*>          The length of the array WORK.  LWORK >= max(1,M,N).
*>          For optimum performance LWORK >= (M+N)*NB, where NB
*>          is the optimal blocksize.
*>
*>          If LWORK = -1, then a workspace query is assumed; the routine
*>          only calculates the optimal size of the WORK array, returns
*>          this value as the first entry of the WORK array, and no error
*>          message related to LWORK is issued by XERBLA.
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date November 2017
*
*> \ingroup doubleGEcomputational
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>  The matrices Q and P are represented as products of elementary
*>  reflectors:
*>
*>  If m >= n,
*>
*>     Q = H(1) H(2) . . . H(n)  and  P = G(1) G(2) . . . G(n-1)
*>
*>  Each H(i) and G(i) has the form:
*>
*>     H(i) = I - tauq * v * v**T  and G(i) = I - taup * u * u**T
*>
*>  where tauq and taup are real scalars, and v and u are real vectors;
*>  v(1:i-1) = 0, v(i) = 1, and v(i+1:m) is stored on exit in A(i+1:m,i);
*>  u(1:i) = 0, u(i+1) = 1, and u(i+2:n) is stored on exit in A(i,i+2:n);
*>  tauq is stored in TAUQ(i) and taup in TAUP(i).
*>
*>  If m < n,
*>
*>     Q = H(1) H(2) . . . H(m-1)  and  P = G(1) G(2) . . . G(m)
*>
*>  Each H(i) and G(i) has the form:
*>
*>     H(i) = I - tauq * v * v**T  and G(i) = I - taup * u * u**T
*>
*>  where tauq and taup are real scalars, and v and u are real vectors;
*>  v(1:i) = 0, v(i+1) = 1, and v(i+2:m) is stored on exit in A(i+2:m,i);
*>  u(1:i-1) = 0, u(i) = 1, and u(i+1:n) is stored on exit in A(i,i+1:n);
*>  tauq is stored in TAUQ(i) and taup in TAUP(i).
*>
*>  The contents of A on exit are illustrated by the following examples:
*>
*>  m = 6 and n = 5 (m > n):          m = 5 and n = 6 (m < n):
*>
*>    (  d   e   u1  u1  u1 )           (  d   u1  u1  u1  u1  u1 )
*>    (  v1  d   e   u2  u2 )           (  e   d   u2  u2  u2  u2 )
*>    (  v1  v2  d   e   u3 )           (  v1  e   d   u3  u3  u3 )
*>    (  v1  v2  v3  d   e  )           (  v1  v2  e   d   u4  u4 )
*>    (  v1  v2  v3  v4  d  )           (  v1  v2  v3  e   d   u5 )
*>    (  v1  v2  v3  v4  v5 )
*>
*>  where d and e denote diagonal and off-diagonal elements of B, vi
*>  denotes an element of the vector defining H(i), and ui an element of
*>  the vector defining G(i).
*> \endverbatim
*>
*  =====================================================================
      SUBROUTINE DGEBRD( M, N, A, LDA, D, E, TAUQ, TAUP, WORK, LWORK,
     $                   INFO )
*
*  -- LAPACK computational routine (version 3.8.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     November 2017
*
*     .. Scalar Arguments ..
      INTEGER            INFO, LDA, LWORK, M, N
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   A( LDA, * ), D( * ), E( * ), TAUP( * ),
     $                   TAUQ( * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ONE
      PARAMETER          ( ONE = 1.0D+0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            LQUERY
      INTEGER            I, IINFO, J, LDWRKX, LDWRKY, LWKOPT, MINMN, NB,
     $                   NBMIN, NX, WS
*     ..
*     .. External Subroutines ..
      EXTERNAL           DGEBD2, DGEMM, DLABRD, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          DBLE, MAX, MIN
*     ..
*     .. External Functions ..
      INTEGER            ILAENV
      EXTERNAL           ILAENV
*     ..
*     .. Executable Statements ..
*
*     Test the input parameters
*
      INFO = 0
      NB = MAX( 1, ILAENV( 1, 'DGEBRD', ' ', M, N, -1, -1 ) )
      LWKOPT = ( M+N )*NB
      WORK( 1 ) = DBLE( LWKOPT )
      LQUERY = ( LWORK.EQ.-1 )
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -4
      ELSE IF( LWORK.LT.MAX( 1, M, N ) .AND. .NOT.LQUERY ) THEN
         INFO = -10
      END IF
      IF( INFO.LT.0 ) THEN
         CALL XERBLA( 'DGEBRD', -INFO )
         RETURN
      ELSE IF( LQUERY ) THEN
         RETURN
      END IF
*
*     Quick return if possible
*
      MINMN = MIN( M, N )
      IF( MINMN.EQ.0 ) THEN
         WORK( 1 ) = 1
         RETURN
      END IF
*
      WS = MAX( M, N )
      LDWRKX = M
      LDWRKY = N
*
      IF( NB.GT.1 .AND. NB.LT.MINMN ) THEN
*
*        Set the crossover point NX.
*
         NX = MAX( NB, ILAENV( 3, 'DGEBRD', ' ', M, N, -1, -1 ) )
*
*        Determine when to switch from blocked to unblocked code.
*
         IF( NX.LT.MINMN ) THEN
            WS = ( M+N )*NB
            IF( LWORK.LT.WS ) THEN
*
*              Not enough work space for the optimal NB, consider using
*              a smaller block size.
*
               NBMIN = ILAENV( 2, 'DGEBRD', ' ', M, N, -1, -1 )
               IF( LWORK.GE.( M+N )*NBMIN ) THEN
                  NB = LWORK / ( M+N )
               ELSE
                  NB = 1
                  NX = MINMN
               END IF
            END IF
         END IF
      ELSE
         NX = MINMN
      END IF
*
      DO 30 I = 1, MINMN - NX, NB
*
*        Reduce rows and columns i:i+nb-1 to bidiagonal form and return
*        the matrices X and Y which are needed to update the unreduced
*        part of the matrix
*
         CALL DLABRD( M-I+1, N-I+1, NB, A( I, I ), LDA, D( I ), E( I ),
     $                TAUQ( I ), TAUP( I ), WORK, LDWRKX,
     $                WORK( LDWRKX*NB+1 ), LDWRKY )
*
*        Update the trailing submatrix A(i+nb:m,i+nb:n), using an update
*        of the form  A := A - V*Y**T - X*U**T
*
         CALL DGEMM( 'No transpose', 'Transpose', M-I-NB+1, N-I-NB+1,
     $               NB, -ONE, A( I+NB, I ), LDA,
     $               WORK( LDWRKX*NB+NB+1 ), LDWRKY, ONE,
     $               A( I+NB, I+NB ), LDA )
         CALL DGEMM( 'No transpose', 'No transpose', M-I-NB+1, N-I-NB+1,
     $               NB, -ONE, WORK( NB+1 ), LDWRKX, A( I, I+NB ), LDA,
     $               ONE, A( I+NB, I+NB ), LDA )
*
*        Copy diagonal and off-diagonal elements of B back into A
*
         IF( M.GE.N ) THEN
            DO 10 J = I, I + NB - 1
               A( J, J ) = D( J )
               A( J, J+1 ) = E( J )
   10       CONTINUE
         ELSE
            DO 20 J = I, I + NB - 1
               A( J, J ) = D( J )
               A( J+1, J ) = E( J )
   20       CONTINUE
         END IF
   30 CONTINUE
*
*     Use unblocked code to reduce the remainder of the matrix
*
      CALL DGEBD2( M-I+1, N-I+1, A( I, I ), LDA, D( I ), E( I ),
     $             TAUQ( I ), TAUP( I ), WORK, IINFO )
      WORK( 1 ) = WS
      RETURN
*
*     End of DGEBRD
*
      END
*> \brief \b DGECON
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGECON + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgecon.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgecon.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgecon.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGECON( NORM, N, A, LDA, ANORM, RCOND, WORK, IWORK,
*                          INFO )
*
*       .. Scalar Arguments ..
*       CHARACTER          NORM
*       INTEGER            INFO, LDA, N
*       DOUBLE PRECISION   ANORM, RCOND
*       ..
*       .. Array Arguments ..
*       INTEGER            IWORK( * )
*       DOUBLE PRECISION   A( LDA, * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGECON estimates the reciprocal of the condition number of a general
*> real matrix A, in either the 1-norm or the infinity-norm, using
*> the LU factorization computed by DGETRF.
*>
*> An estimate is obtained for norm(inv(A)), and the reciprocal of the
*> condition number is computed as
*>    RCOND = 1 / ( norm(A) * norm(inv(A)) ).
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] NORM
*> \verbatim
*>          NORM is CHARACTER*1
*>          Specifies whether the 1-norm condition number or the
*>          infinity-norm condition number is required:
*>          = '1' or 'O':  1-norm;
*>          = 'I':         Infinity-norm.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The order of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          The factors L and U from the factorization A = P*L*U
*>          as computed by DGETRF.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,N).
*> \endverbatim
*>
*> \param[in] ANORM
*> \verbatim
*>          ANORM is DOUBLE PRECISION
*>          If NORM = '1' or 'O', the 1-norm of the original matrix A.
*>          If NORM = 'I', the infinity-norm of the original matrix A.
*> \endverbatim
*>
*> \param[out] RCOND
*> \verbatim
*>          RCOND is DOUBLE PRECISION
*>          The reciprocal of the condition number of the matrix A,
*>          computed as RCOND = 1/(norm(A) * norm(inv(A))).
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (4*N)
*> \endverbatim
*>
*> \param[out] IWORK
*> \verbatim
*>          IWORK is INTEGER array, dimension (N)
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEcomputational
*
*  =====================================================================
      SUBROUTINE DGECON( NORM, N, A, LDA, ANORM, RCOND, WORK, IWORK,
     $                   INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      CHARACTER          NORM
      INTEGER            INFO, LDA, N
      DOUBLE PRECISION   ANORM, RCOND
*     ..
*     .. Array Arguments ..
      INTEGER            IWORK( * )
      DOUBLE PRECISION   A( LDA, * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ONE, ZERO
      PARAMETER          ( ONE = 1.0D+0, ZERO = 0.0D+0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            ONENRM
      CHARACTER          NORMIN
      INTEGER            IX, KASE, KASE1
      DOUBLE PRECISION   AINVNM, SCALE, SL, SMLNUM, SU
*     ..
*     .. Local Arrays ..
      INTEGER            ISAVE( 3 )
*     ..
*     .. External Functions ..
      LOGICAL            LSAME
      INTEGER            IDAMAX
      DOUBLE PRECISION   DLAMCH
      EXTERNAL           LSAME, IDAMAX, DLAMCH
*     ..
*     .. External Subroutines ..
      EXTERNAL           DLACN2, DLATRS, DRSCL, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          ABS, MAX
*     ..
*     .. Executable Statements ..
*
*     Test the input parameters.
*
      INFO = 0
      ONENRM = NORM.EQ.'1' .OR. LSAME( NORM, 'O' )
      IF( .NOT.ONENRM .AND. .NOT.LSAME( NORM, 'I' ) ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
         INFO = -4
      ELSE IF( ANORM.LT.ZERO ) THEN
         INFO = -5
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGECON', -INFO )
         RETURN
      END IF
*
*     Quick return if possible
*
      RCOND = ZERO
      IF( N.EQ.0 ) THEN
         RCOND = ONE
         RETURN
      ELSE IF( ANORM.EQ.ZERO ) THEN
         RETURN
      END IF
*
      SMLNUM = DLAMCH( 'Safe minimum' )
*
*     Estimate the norm of inv(A).
*
      AINVNM = ZERO
      NORMIN = 'N'
      IF( ONENRM ) THEN
         KASE1 = 1
      ELSE
         KASE1 = 2
      END IF
      KASE = 0
   10 CONTINUE
      CALL DLACN2( N, WORK( N+1 ), WORK, IWORK, AINVNM, KASE, ISAVE )
      IF( KASE.NE.0 ) THEN
         IF( KASE.EQ.KASE1 ) THEN
*
*           Multiply by inv(L).
*
            CALL DLATRS( 'Lower', 'No transpose', 'Unit', NORMIN, N, A,
     $                   LDA, WORK, SL, WORK( 2*N+1 ), INFO )
*
*           Multiply by inv(U).
*
            CALL DLATRS( 'Upper', 'No transpose', 'Non-unit', NORMIN, N,
     $                   A, LDA, WORK, SU, WORK( 3*N+1 ), INFO )
         ELSE
*
*           Multiply by inv(U**T).
*
            CALL DLATRS( 'Upper', 'Transpose', 'Non-unit', NORMIN, N, A,
     $                   LDA, WORK, SU, WORK( 3*N+1 ), INFO )
*
*           Multiply by inv(L**T).
*
            CALL DLATRS( 'Lower', 'Transpose', 'Unit', NORMIN, N, A,
     $                   LDA, WORK, SL, WORK( 2*N+1 ), INFO )
         END IF
*
*        Divide X by 1/(SL*SU) if doing so will not cause overflow.
*
         SCALE = SL*SU
         NORMIN = 'Y'
         IF( SCALE.NE.ONE ) THEN
            IX = IDAMAX( N, WORK, 1 )
            IF( SCALE.LT.ABS( WORK( IX ) )*SMLNUM .OR. SCALE.EQ.ZERO )
     $         GO TO 20
            CALL DRSCL( N, SCALE, WORK, 1 )
         END IF
         GO TO 10
      END IF
*
*     Compute the estimate of the reciprocal condition number.
*
      IF( AINVNM.NE.ZERO )
     $   RCOND = ( ONE / AINVNM ) / ANORM
*
   20 CONTINUE
      RETURN
*
*     End of DGECON
*
      END
*> \brief \b DGEEQU
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGEEQU + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgeequ.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgeequ.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgeequ.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGEEQU( M, N, A, LDA, R, C, ROWCND, COLCND, AMAX,
*                          INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, LDA, M, N
*       DOUBLE PRECISION   AMAX, COLCND, ROWCND
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   A( LDA, * ), C( * ), R( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGEEQU computes row and column scalings intended to equilibrate an
*> M-by-N matrix A and reduce its condition number.  R returns the row
*> scale factors and C the column scale factors, chosen to try to make
*> the largest element in each row and column of the matrix B with
*> elements B(i,j)=R(i)*A(i,j)*C(j) have absolute value 1.
*>
*> R(i) and C(j) are restricted to be between SMLNUM = smallest safe
*> number and BIGNUM = largest safe number.  Use of these scaling
*> factors is not guaranteed to reduce the condition number of A but
*> works well in practice.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A.  M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          The M-by-N matrix whose equilibration factors are
*>          to be computed.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,M).
*> \endverbatim
*>
*> \param[out] R
*> \verbatim
*>          R is DOUBLE PRECISION array, dimension (M)
*>          If INFO = 0 or INFO > M, R contains the row scale factors
*>          for A.
*> \endverbatim
*>
*> \param[out] C
*> \verbatim
*>          C is DOUBLE PRECISION array, dimension (N)
*>          If INFO = 0,  C contains the column scale factors for A.
*> \endverbatim
*>
*> \param[out] ROWCND
*> \verbatim
*>          ROWCND is DOUBLE PRECISION
*>          If INFO = 0 or INFO > M, ROWCND contains the ratio of the
*>          smallest R(i) to the largest R(i).  If ROWCND >= 0.1 and
*>          AMAX is neither too large nor too small, it is not worth
*>          scaling by R.
*> \endverbatim
*>
*> \param[out] COLCND
*> \verbatim
*>          COLCND is DOUBLE PRECISION
*>          If INFO = 0, COLCND contains the ratio of the smallest
*>          C(i) to the largest C(i).  If COLCND >= 0.1, it is not
*>          worth scaling by C.
*> \endverbatim
*>
*> \param[out] AMAX
*> \verbatim
*>          AMAX is DOUBLE PRECISION
*>          Absolute value of largest matrix element.  If AMAX is very
*>          close to overflow or very close to underflow, the matrix
*>          should be scaled.
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value
*>          > 0:  if INFO = i,  and i is
*>                <= M:  the i-th row of A is exactly zero
*>                >  M:  the (i-M)-th column of A is exactly zero
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEcomputational
*
*  =====================================================================
      SUBROUTINE DGEEQU( M, N, A, LDA, R, C, ROWCND, COLCND, AMAX,
     $                   INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER            INFO, LDA, M, N
      DOUBLE PRECISION   AMAX, COLCND, ROWCND
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   A( LDA, * ), C( * ), R( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ONE, ZERO
      PARAMETER          ( ONE = 1.0D+0, ZERO = 0.0D+0 )
*     ..
*     .. Local Scalars ..
      INTEGER            I, J
      DOUBLE PRECISION   BIGNUM, RCMAX, RCMIN, SMLNUM
*     ..
*     .. External Functions ..
      DOUBLE PRECISION   DLAMCH
      EXTERNAL           DLAMCH
*     ..
*     .. External Subroutines ..
      EXTERNAL           XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          ABS, MAX, MIN
*     ..
*     .. Executable Statements ..
*
*     Test the input parameters.
*
      INFO = 0
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -4
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGEEQU', -INFO )
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( M.EQ.0 .OR. N.EQ.0 ) THEN
         ROWCND = ONE
         COLCND = ONE
         AMAX = ZERO
         RETURN
      END IF
*
*     Get machine constants.
*
      SMLNUM = DLAMCH( 'S' )
      BIGNUM = ONE / SMLNUM
*
*     Compute row scale factors.
*
      DO 10 I = 1, M
         R( I ) = ZERO
   10 CONTINUE
*
*     Find the maximum element in each row.
*
      DO 30 J = 1, N
         DO 20 I = 1, M
            R( I ) = MAX( R( I ), ABS( A( I, J ) ) )
   20    CONTINUE
   30 CONTINUE
*
*     Find the maximum and minimum scale factors.
*
      RCMIN = BIGNUM
      RCMAX = ZERO
      DO 40 I = 1, M
         RCMAX = MAX( RCMAX, R( I ) )
         RCMIN = MIN( RCMIN, R( I ) )
   40 CONTINUE
      AMAX = RCMAX
*
      IF( RCMIN.EQ.ZERO ) THEN
*
*        Find the first zero scale factor and return an error code.
*
         DO 50 I = 1, M
            IF( R( I ).EQ.ZERO ) THEN
               INFO = I
               RETURN
            END IF
   50    CONTINUE
      ELSE
*
*        Invert the scale factors.
*
         DO 60 I = 1, M
            R( I ) = ONE / MIN( MAX( R( I ), SMLNUM ), BIGNUM )
   60    CONTINUE
*
*        Compute ROWCND = min(R(I)) / max(R(I))
*
         ROWCND = MAX( RCMIN, SMLNUM ) / MIN( RCMAX, BIGNUM )
      END IF
*
*     Compute column scale factors
*
      DO 70 J = 1, N
         C( J ) = ZERO
   70 CONTINUE
*
*     Find the maximum element in each column,
*     assuming the row scaling computed above.
*
      DO 90 J = 1, N
         DO 80 I = 1, M
            C( J ) = MAX( C( J ), ABS( A( I, J ) )*R( I ) )
   80    CONTINUE
   90 CONTINUE
*
*     Find the maximum and minimum scale factors.
*
      RCMIN = BIGNUM
      RCMAX = ZERO
      DO 100 J = 1, N
         RCMIN = MIN( RCMIN, C( J ) )
         RCMAX = MAX( RCMAX, C( J ) )
  100 CONTINUE
*
      IF( RCMIN.EQ.ZERO ) THEN
*
*        Find the first zero scale factor and return an error code.
*
         DO 110 J = 1, N
            IF( C( J ).EQ.ZERO ) THEN
               INFO = M + J
               RETURN
            END IF
  110    CONTINUE
      ELSE
*
*        Invert the scale factors.
*
         DO 120 J = 1, N
            C( J ) = ONE / MIN( MAX( C( J ), SMLNUM ), BIGNUM )
  120    CONTINUE
*
*        Compute COLCND = min(C(J)) / max(C(J))
*
         COLCND = MAX( RCMIN, SMLNUM ) / MIN( RCMAX, BIGNUM )
      END IF
*
      RETURN
*
*     End of DGEEQU
*
      END
*> \brief \b DGEEQUB
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGEEQUB + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgeequb.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgeequb.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgeequb.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGEEQUB( M, N, A, LDA, R, C, ROWCND, COLCND, AMAX,
*                           INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, LDA, M, N
*       DOUBLE PRECISION   AMAX, COLCND, ROWCND
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   A( LDA, * ), C( * ), R( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGEEQUB computes row and column scalings intended to equilibrate an
*> M-by-N matrix A and reduce its condition number.  R returns the row
*> scale factors and C the column scale factors, chosen to try to make
*> the largest element in each row and column of the matrix B with
*> elements B(i,j)=R(i)*A(i,j)*C(j) have an absolute value of at most
*> the radix.
*>
*> R(i) and C(j) are restricted to be a power of the radix between
*> SMLNUM = smallest safe number and BIGNUM = largest safe number.  Use
*> of these scaling factors is not guaranteed to reduce the condition
*> number of A but works well in practice.
*>
*> This routine differs from DGEEQU by restricting the scaling factors
*> to a power of the radix.  Barring over- and underflow, scaling by
*> these factors introduces no additional rounding errors.  However, the
*> scaled entries' magnitudes are no longer approximately 1 but lie
*> between sqrt(radix) and 1/sqrt(radix).
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A.  M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          The M-by-N matrix whose equilibration factors are
*>          to be computed.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,M).
*> \endverbatim
*>
*> \param[out] R
*> \verbatim
*>          R is DOUBLE PRECISION array, dimension (M)
*>          If INFO = 0 or INFO > M, R contains the row scale factors
*>          for A.
*> \endverbatim
*>
*> \param[out] C
*> \verbatim
*>          C is DOUBLE PRECISION array, dimension (N)
*>          If INFO = 0,  C contains the column scale factors for A.
*> \endverbatim
*>
*> \param[out] ROWCND
*> \verbatim
*>          ROWCND is DOUBLE PRECISION
*>          If INFO = 0 or INFO > M, ROWCND contains the ratio of the
*>          smallest R(i) to the largest R(i).  If ROWCND >= 0.1 and
*>          AMAX is neither too large nor too small, it is not worth
*>          scaling by R.
*> \endverbatim
*>
*> \param[out] COLCND
*> \verbatim
*>          COLCND is DOUBLE PRECISION
*>          If INFO = 0, COLCND contains the ratio of the smallest
*>          C(i) to the largest C(i).  If COLCND >= 0.1, it is not
*>          worth scaling by C.
*> \endverbatim
*>
*> \param[out] AMAX
*> \verbatim
*>          AMAX is DOUBLE PRECISION
*>          Absolute value of largest matrix element.  If AMAX is very
*>          close to overflow or very close to underflow, the matrix
*>          should be scaled.
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value
*>          > 0:  if INFO = i,  and i is
*>                <= M:  the i-th row of A is exactly zero
*>                >  M:  the (i-M)-th column of A is exactly zero
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEcomputational
*
*  =====================================================================
      SUBROUTINE DGEEQUB( M, N, A, LDA, R, C, ROWCND, COLCND, AMAX,
     $                    INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER            INFO, LDA, M, N
      DOUBLE PRECISION   AMAX, COLCND, ROWCND
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   A( LDA, * ), C( * ), R( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ONE, ZERO
      PARAMETER          ( ONE = 1.0D+0, ZERO = 0.0D+0 )
*     ..
*     .. Local Scalars ..
      INTEGER            I, J
      DOUBLE PRECISION   BIGNUM, RCMAX, RCMIN, SMLNUM, RADIX, LOGRDX
*     ..
*     .. External Functions ..
      DOUBLE PRECISION   DLAMCH
      EXTERNAL           DLAMCH
*     ..
*     .. External Subroutines ..
      EXTERNAL           XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          ABS, MAX, MIN, LOG
*     ..
*     .. Executable Statements ..
*
*     Test the input parameters.
*
      INFO = 0
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -4
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGEEQUB', -INFO )
         RETURN
      END IF
*
*     Quick return if possible.
*
      IF( M.EQ.0 .OR. N.EQ.0 ) THEN
         ROWCND = ONE
         COLCND = ONE
         AMAX = ZERO
         RETURN
      END IF
*
*     Get machine constants.  Assume SMLNUM is a power of the radix.
*
      SMLNUM = DLAMCH( 'S' )
      BIGNUM = ONE / SMLNUM
      RADIX = DLAMCH( 'B' )
      LOGRDX = LOG( RADIX )
*
*     Compute row scale factors.
*
      DO 10 I = 1, M
         R( I ) = ZERO
   10 CONTINUE
*
*     Find the maximum element in each row.
*
      DO 30 J = 1, N
         DO 20 I = 1, M
            R( I ) = MAX( R( I ), ABS( A( I, J ) ) )
   20    CONTINUE
   30 CONTINUE
      DO I = 1, M
         IF( R( I ).GT.ZERO ) THEN
            R( I ) = RADIX**INT( LOG( R( I ) ) / LOGRDX )
         END IF
      END DO
*
*     Find the maximum and minimum scale factors.
*
      RCMIN = BIGNUM
      RCMAX = ZERO
      DO 40 I = 1, M
         RCMAX = MAX( RCMAX, R( I ) )
         RCMIN = MIN( RCMIN, R( I ) )
   40 CONTINUE
      AMAX = RCMAX
*
      IF( RCMIN.EQ.ZERO ) THEN
*
*        Find the first zero scale factor and return an error code.
*
         DO 50 I = 1, M
            IF( R( I ).EQ.ZERO ) THEN
               INFO = I
               RETURN
            END IF
   50    CONTINUE
      ELSE
*
*        Invert the scale factors.
*
         DO 60 I = 1, M
            R( I ) = ONE / MIN( MAX( R( I ), SMLNUM ), BIGNUM )
   60    CONTINUE
*
*        Compute ROWCND = min(R(I)) / max(R(I)).
*
         ROWCND = MAX( RCMIN, SMLNUM ) / MIN( RCMAX, BIGNUM )
      END IF
*
*     Compute column scale factors
*
      DO 70 J = 1, N
         C( J ) = ZERO
   70 CONTINUE
*
*     Find the maximum element in each column,
*     assuming the row scaling computed above.
*
      DO 90 J = 1, N
         DO 80 I = 1, M
            C( J ) = MAX( C( J ), ABS( A( I, J ) )*R( I ) )
   80    CONTINUE
         IF( C( J ).GT.ZERO ) THEN
            C( J ) = RADIX**INT( LOG( C( J ) ) / LOGRDX )
         END IF
   90 CONTINUE
*
*     Find the maximum and minimum scale factors.
*
      RCMIN = BIGNUM
      RCMAX = ZERO
      DO 100 J = 1, N
         RCMIN = MIN( RCMIN, C( J ) )
         RCMAX = MAX( RCMAX, C( J ) )
  100 CONTINUE
*
      IF( RCMIN.EQ.ZERO ) THEN
*
*        Find the first zero scale factor and return an error code.
*
         DO 110 J = 1, N
            IF( C( J ).EQ.ZERO ) THEN
               INFO = M + J
               RETURN
            END IF
  110    CONTINUE
      ELSE
*
*        Invert the scale factors.
*
         DO 120 J = 1, N
            C( J ) = ONE / MIN( MAX( C( J ), SMLNUM ), BIGNUM )
  120    CONTINUE
*
*        Compute COLCND = min(C(J)) / max(C(J)).
*
         COLCND = MAX( RCMIN, SMLNUM ) / MIN( RCMAX, BIGNUM )
      END IF
*
      RETURN
*
*     End of DGEEQUB
*
      END
*> \brief <b> DGEES computes the eigenvalues, the Schur form, and, optionally, the matrix of Schur vectors for GE matrices</b>
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGEES + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgees.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgees.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgees.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGEES( JOBVS, SORT, SELECT, N, A, LDA, SDIM, WR, WI,
*                         VS, LDVS, WORK, LWORK, BWORK, INFO )
*
*       .. Scalar Arguments ..
*       CHARACTER          JOBVS, SORT
*       INTEGER            INFO, LDA, LDVS, LWORK, N, SDIM
*       ..
*       .. Array Arguments ..
*       LOGICAL            BWORK( * )
*       DOUBLE PRECISION   A( LDA, * ), VS( LDVS, * ), WI( * ), WORK( * ),
*      $                   WR( * )
*       ..
*       .. Function Arguments ..
*       LOGICAL            SELECT
*       EXTERNAL           SELECT
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGEES computes for an N-by-N real nonsymmetric matrix A, the
*> eigenvalues, the real Schur form T, and, optionally, the matrix of
*> Schur vectors Z.  This gives the Schur factorization A = Z*T*(Z**T).
*>
*> Optionally, it also orders the eigenvalues on the diagonal of the
*> real Schur form so that selected eigenvalues are at the top left.
*> The leading columns of Z then form an orthonormal basis for the
*> invariant subspace corresponding to the selected eigenvalues.
*>
*> A matrix is in real Schur form if it is upper quasi-triangular with
*> 1-by-1 and 2-by-2 blocks. 2-by-2 blocks will be standardized in the
*> form
*>         [  a  b  ]
*>         [  c  a  ]
*>
*> where b*c < 0. The eigenvalues of such a block are a +- sqrt(bc).
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] JOBVS
*> \verbatim
*>          JOBVS is CHARACTER*1
*>          = 'N': Schur vectors are not computed;
*>          = 'V': Schur vectors are computed.
*> \endverbatim
*>
*> \param[in] SORT
*> \verbatim
*>          SORT is CHARACTER*1
*>          Specifies whether or not to order the eigenvalues on the
*>          diagonal of the Schur form.
*>          = 'N': Eigenvalues are not ordered;
*>          = 'S': Eigenvalues are ordered (see SELECT).
*> \endverbatim
*>
*> \param[in] SELECT
*> \verbatim
*>          SELECT is a LOGICAL FUNCTION of two DOUBLE PRECISION arguments
*>          SELECT must be declared EXTERNAL in the calling subroutine.
*>          If SORT = 'S', SELECT is used to select eigenvalues to sort
*>          to the top left of the Schur form.
*>          If SORT = 'N', SELECT is not referenced.
*>          An eigenvalue WR(j)+sqrt(-1)*WI(j) is selected if
*>          SELECT(WR(j),WI(j)) is true; i.e., if either one of a complex
*>          conjugate pair of eigenvalues is selected, then both complex
*>          eigenvalues are selected.
*>          Note that a selected complex eigenvalue may no longer
*>          satisfy SELECT(WR(j),WI(j)) = .TRUE. after ordering, since
*>          ordering may change the value of complex eigenvalues
*>          (especially if the eigenvalue is ill-conditioned); in this
*>          case INFO is set to N+2 (see INFO below).
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The order of the matrix A. N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the N-by-N matrix A.
*>          On exit, A has been overwritten by its real Schur form T.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,N).
*> \endverbatim
*>
*> \param[out] SDIM
*> \verbatim
*>          SDIM is INTEGER
*>          If SORT = 'N', SDIM = 0.
*>          If SORT = 'S', SDIM = number of eigenvalues (after sorting)
*>                         for which SELECT is true. (Complex conjugate
*>                         pairs for which SELECT is true for either
*>                         eigenvalue count as 2.)
*> \endverbatim
*>
*> \param[out] WR
*> \verbatim
*>          WR is DOUBLE PRECISION array, dimension (N)
*> \endverbatim
*>
*> \param[out] WI
*> \verbatim
*>          WI is DOUBLE PRECISION array, dimension (N)
*>          WR and WI contain the real and imaginary parts,
*>          respectively, of the computed eigenvalues in the same order
*>          that they appear on the diagonal of the output Schur form T.
*>          Complex conjugate pairs of eigenvalues will appear
*>          consecutively with the eigenvalue having the positive
*>          imaginary part first.
*> \endverbatim
*>
*> \param[out] VS
*> \verbatim
*>          VS is DOUBLE PRECISION array, dimension (LDVS,N)
*>          If JOBVS = 'V', VS contains the orthogonal matrix Z of Schur
*>          vectors.
*>          If JOBVS = 'N', VS is not referenced.
*> \endverbatim
*>
*> \param[in] LDVS
*> \verbatim
*>          LDVS is INTEGER
*>          The leading dimension of the array VS.  LDVS >= 1; if
*>          JOBVS = 'V', LDVS >= N.
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK))
*>          On exit, if INFO = 0, WORK(1) contains the optimal LWORK.
*> \endverbatim
*>
*> \param[in] LWORK
*> \verbatim
*>          LWORK is INTEGER
*>          The dimension of the array WORK.  LWORK >= max(1,3*N).
*>          For good performance, LWORK must generally be larger.
*>
*>          If LWORK = -1, then a workspace query is assumed; the routine
*>          only calculates the optimal size of the WORK array, returns
*>          this value as the first entry of the WORK array, and no error
*>          message related to LWORK is issued by XERBLA.
*> \endverbatim
*>
*> \param[out] BWORK
*> \verbatim
*>          BWORK is LOGICAL array, dimension (N)
*>          Not referenced if SORT = 'N'.
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0: successful exit
*>          < 0: if INFO = -i, the i-th argument had an illegal value.
*>          > 0: if INFO = i, and i is
*>             <= N: the QR algorithm failed to compute all the
*>                   eigenvalues; elements 1:ILO-1 and i+1:N of WR and WI
*>                   contain those eigenvalues which have converged; if
*>                   JOBVS = 'V', VS contains the matrix which reduces A
*>                   to its partially converged Schur form.
*>             = N+1: the eigenvalues could not be reordered because some
*>                   eigenvalues were too close to separate (the problem
*>                   is very ill-conditioned);
*>             = N+2: after reordering, roundoff changed values of some
*>                   complex eigenvalues so that leading eigenvalues in
*>                   the Schur form no longer satisfy SELECT=.TRUE.  This
*>                   could also be caused by underflow due to scaling.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEeigen
*
*  =====================================================================
      SUBROUTINE DGEES( JOBVS, SORT, SELECT, N, A, LDA, SDIM, WR, WI,
     $                  VS, LDVS, WORK, LWORK, BWORK, INFO )
*
*  -- LAPACK driver routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      CHARACTER          JOBVS, SORT
      INTEGER            INFO, LDA, LDVS, LWORK, N, SDIM
*     ..
*     .. Array Arguments ..
      LOGICAL            BWORK( * )
      DOUBLE PRECISION   A( LDA, * ), VS( LDVS, * ), WI( * ), WORK( * ),
     $                   WR( * )
*     ..
*     .. Function Arguments ..
      LOGICAL            SELECT
      EXTERNAL           SELECT
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ZERO, ONE
      PARAMETER          ( ZERO = 0.0D0, ONE = 1.0D0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            CURSL, LASTSL, LQUERY, LST2SL, SCALEA, WANTST,
     $                   WANTVS
      INTEGER            HSWORK, I, I1, I2, IBAL, ICOND, IERR, IEVAL,
     $                   IHI, ILO, INXT, IP, ITAU, IWRK, MAXWRK, MINWRK
      DOUBLE PRECISION   ANRM, BIGNUM, CSCALE, EPS, S, SEP, SMLNUM
*     ..
*     .. Local Arrays ..
      INTEGER            IDUM( 1 )
      DOUBLE PRECISION   DUM( 1 )
*     ..
*     .. External Subroutines ..
      EXTERNAL           DCOPY, DGEBAK, DGEBAL, DGEHRD, DHSEQR, DLACPY,
     $                   DLABAD, DLASCL, DORGHR, DSWAP, DTRSEN, XERBLA
*     ..
*     .. External Functions ..
      LOGICAL            LSAME
      INTEGER            ILAENV
      DOUBLE PRECISION   DLAMCH, DLANGE
      EXTERNAL           LSAME, ILAENV, DLAMCH, DLANGE
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, SQRT
*     ..
*     .. Executable Statements ..
*
*     Test the input arguments
*
      INFO = 0
      LQUERY = ( LWORK.EQ.-1 )
      WANTVS = LSAME( JOBVS, 'V' )
      WANTST = LSAME( SORT, 'S' )
      IF( ( .NOT.WANTVS ) .AND. ( .NOT.LSAME( JOBVS, 'N' ) ) ) THEN
         INFO = -1
      ELSE IF( ( .NOT.WANTST ) .AND. ( .NOT.LSAME( SORT, 'N' ) ) ) THEN
         INFO = -2
      ELSE IF( N.LT.0 ) THEN
         INFO = -4
      ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
         INFO = -6
      ELSE IF( LDVS.LT.1 .OR. ( WANTVS .AND. LDVS.LT.N ) ) THEN
         INFO = -11
      END IF
*
*     Compute workspace
*      (Note: Comments in the code beginning "Workspace:" describe the
*       minimal amount of workspace needed at that point in the code,
*       as well as the preferred amount for good performance.
*       NB refers to the optimal block size for the immediately
*       following subroutine, as returned by ILAENV.
*       HSWORK refers to the workspace preferred by DHSEQR, as
*       calculated below. HSWORK is computed assuming ILO=1 and IHI=N,
*       the worst case.)
*
      IF( INFO.EQ.0 ) THEN
         IF( N.EQ.0 ) THEN
            MINWRK = 1
            MAXWRK = 1
         ELSE
            MAXWRK = 2*N + N*ILAENV( 1, 'DGEHRD', ' ', N, 1, N, 0 )
            MINWRK = 3*N
*
            CALL DHSEQR( 'S', JOBVS, N, 1, N, A, LDA, WR, WI, VS, LDVS,
     $             WORK, -1, IEVAL )
            HSWORK = WORK( 1 )
*
            IF( .NOT.WANTVS ) THEN
               MAXWRK = MAX( MAXWRK, N + HSWORK )
            ELSE
               MAXWRK = MAX( MAXWRK, 2*N + ( N - 1 )*ILAENV( 1,
     $                       'DORGHR', ' ', N, 1, N, -1 ) )
               MAXWRK = MAX( MAXWRK, N + HSWORK )
            END IF
         END IF
         WORK( 1 ) = MAXWRK
*
         IF( LWORK.LT.MINWRK .AND. .NOT.LQUERY ) THEN
            INFO = -13
         END IF
      END IF
*
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGEES ', -INFO )
         RETURN
      ELSE IF( LQUERY ) THEN
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( N.EQ.0 ) THEN
         SDIM = 0
         RETURN
      END IF
*
*     Get machine constants
*
      EPS = DLAMCH( 'P' )
      SMLNUM = DLAMCH( 'S' )
      BIGNUM = ONE / SMLNUM
      CALL DLABAD( SMLNUM, BIGNUM )
      SMLNUM = SQRT( SMLNUM ) / EPS
      BIGNUM = ONE / SMLNUM
*
*     Scale A if max element outside range [SMLNUM,BIGNUM]
*
      ANRM = DLANGE( 'M', N, N, A, LDA, DUM )
      SCALEA = .FALSE.
      IF( ANRM.GT.ZERO .AND. ANRM.LT.SMLNUM ) THEN
         SCALEA = .TRUE.
         CSCALE = SMLNUM
      ELSE IF( ANRM.GT.BIGNUM ) THEN
         SCALEA = .TRUE.
         CSCALE = BIGNUM
      END IF
      IF( SCALEA )
     $   CALL DLASCL( 'G', 0, 0, ANRM, CSCALE, N, N, A, LDA, IERR )
*
*     Permute the matrix to make it more nearly triangular
*     (Workspace: need N)
*
      IBAL = 1
      CALL DGEBAL( 'P', N, A, LDA, ILO, IHI, WORK( IBAL ), IERR )
*
*     Reduce to upper Hessenberg form
*     (Workspace: need 3*N, prefer 2*N+N*NB)
*
      ITAU = N + IBAL
      IWRK = N + ITAU
      CALL DGEHRD( N, ILO, IHI, A, LDA, WORK( ITAU ), WORK( IWRK ),
     $             LWORK-IWRK+1, IERR )
*
      IF( WANTVS ) THEN
*
*        Copy Householder vectors to VS
*
         CALL DLACPY( 'L', N, N, A, LDA, VS, LDVS )
*
*        Generate orthogonal matrix in VS
*        (Workspace: need 3*N-1, prefer 2*N+(N-1)*NB)
*
         CALL DORGHR( N, ILO, IHI, VS, LDVS, WORK( ITAU ), WORK( IWRK ),
     $                LWORK-IWRK+1, IERR )
      END IF
*
      SDIM = 0
*
*     Perform QR iteration, accumulating Schur vectors in VS if desired
*     (Workspace: need N+1, prefer N+HSWORK (see comments) )
*
      IWRK = ITAU
      CALL DHSEQR( 'S', JOBVS, N, ILO, IHI, A, LDA, WR, WI, VS, LDVS,
     $             WORK( IWRK ), LWORK-IWRK+1, IEVAL )
      IF( IEVAL.GT.0 )
     $   INFO = IEVAL
*
*     Sort eigenvalues if desired
*
      IF( WANTST .AND. INFO.EQ.0 ) THEN
         IF( SCALEA ) THEN
            CALL DLASCL( 'G', 0, 0, CSCALE, ANRM, N, 1, WR, N, IERR )
            CALL DLASCL( 'G', 0, 0, CSCALE, ANRM, N, 1, WI, N, IERR )
         END IF
         DO 10 I = 1, N
            BWORK( I ) = SELECT( WR( I ), WI( I ) )
   10    CONTINUE
*
*        Reorder eigenvalues and transform Schur vectors
*        (Workspace: none needed)
*
         CALL DTRSEN( 'N', JOBVS, BWORK, N, A, LDA, VS, LDVS, WR, WI,
     $                SDIM, S, SEP, WORK( IWRK ), LWORK-IWRK+1, IDUM, 1,
     $                ICOND )
         IF( ICOND.GT.0 )
     $      INFO = N + ICOND
      END IF
*
      IF( WANTVS ) THEN
*
*        Undo balancing
*        (Workspace: need N)
*
         CALL DGEBAK( 'P', 'R', N, ILO, IHI, WORK( IBAL ), N, VS, LDVS,
     $                IERR )
      END IF
*
      IF( SCALEA ) THEN
*
*        Undo scaling for the Schur form of A
*
         CALL DLASCL( 'H', 0, 0, CSCALE, ANRM, N, N, A, LDA, IERR )
         CALL DCOPY( N, A, LDA+1, WR, 1 )
         IF( CSCALE.EQ.SMLNUM ) THEN
*
*           If scaling back towards underflow, adjust WI if an
*           offdiagonal element of a 2-by-2 block in the Schur form
*           underflows.
*
            IF( IEVAL.GT.0 ) THEN
               I1 = IEVAL + 1
               I2 = IHI - 1
               CALL DLASCL( 'G', 0, 0, CSCALE, ANRM, ILO-1, 1, WI,
     $                      MAX( ILO-1, 1 ), IERR )
            ELSE IF( WANTST ) THEN
               I1 = 1
               I2 = N - 1
            ELSE
               I1 = ILO
               I2 = IHI - 1
            END IF
            INXT = I1 - 1
            DO 20 I = I1, I2
               IF( I.LT.INXT )
     $            GO TO 20
               IF( WI( I ).EQ.ZERO ) THEN
                  INXT = I + 1
               ELSE
                  IF( A( I+1, I ).EQ.ZERO ) THEN
                     WI( I ) = ZERO
                     WI( I+1 ) = ZERO
                  ELSE IF( A( I+1, I ).NE.ZERO .AND. A( I, I+1 ).EQ.
     $                     ZERO ) THEN
                     WI( I ) = ZERO
                     WI( I+1 ) = ZERO
                     IF( I.GT.1 )
     $                  CALL DSWAP( I-1, A( 1, I ), 1, A( 1, I+1 ), 1 )
                     IF( N.GT.I+1 )
     $                  CALL DSWAP( N-I-1, A( I, I+2 ), LDA,
     $                              A( I+1, I+2 ), LDA )
                     IF( WANTVS ) THEN
                        CALL DSWAP( N, VS( 1, I ), 1, VS( 1, I+1 ), 1 )
                     END IF
                     A( I, I+1 ) = A( I+1, I )
                     A( I+1, I ) = ZERO
                  END IF
                  INXT = I + 2
               END IF
   20       CONTINUE
         END IF
*
*        Undo scaling for the imaginary part of the eigenvalues
*
         CALL DLASCL( 'G', 0, 0, CSCALE, ANRM, N-IEVAL, 1,
     $                WI( IEVAL+1 ), MAX( N-IEVAL, 1 ), IERR )
      END IF
*
      IF( WANTST .AND. INFO.EQ.0 ) THEN
*
*        Check if reordering successful
*
         LASTSL = .TRUE.
         LST2SL = .TRUE.
         SDIM = 0
         IP = 0
         DO 30 I = 1, N
            CURSL = SELECT( WR( I ), WI( I ) )
            IF( WI( I ).EQ.ZERO ) THEN
               IF( CURSL )
     $            SDIM = SDIM + 1
               IP = 0
               IF( CURSL .AND. .NOT.LASTSL )
     $            INFO = N + 2
            ELSE
               IF( IP.EQ.1 ) THEN
*
*                 Last eigenvalue of conjugate pair
*
                  CURSL = CURSL .OR. LASTSL
                  LASTSL = CURSL
                  IF( CURSL )
     $               SDIM = SDIM + 2
                  IP = -1
                  IF( CURSL .AND. .NOT.LST2SL )
     $               INFO = N + 2
               ELSE
*
*                 First eigenvalue of conjugate pair
*
                  IP = 1
               END IF
            END IF
            LST2SL = LASTSL
            LASTSL = CURSL
   30    CONTINUE
      END IF
*
      WORK( 1 ) = MAXWRK
      RETURN
*
*     End of DGEES
*
      END
*> \brief <b> DGEESX computes the eigenvalues, the Schur form, and, optionally, the matrix of Schur vectors for GE matrices</b>
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGEESX + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgeesx.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgeesx.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgeesx.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGEESX( JOBVS, SORT, SELECT, SENSE, N, A, LDA, SDIM,
*                          WR, WI, VS, LDVS, RCONDE, RCONDV, WORK, LWORK,
*                          IWORK, LIWORK, BWORK, INFO )
*
*       .. Scalar Arguments ..
*       CHARACTER          JOBVS, SENSE, SORT
*       INTEGER            INFO, LDA, LDVS, LIWORK, LWORK, N, SDIM
*       DOUBLE PRECISION   RCONDE, RCONDV
*       ..
*       .. Array Arguments ..
*       LOGICAL            BWORK( * )
*       INTEGER            IWORK( * )
*       DOUBLE PRECISION   A( LDA, * ), VS( LDVS, * ), WI( * ), WORK( * ),
*      $                   WR( * )
*       ..
*       .. Function Arguments ..
*       LOGICAL            SELECT
*       EXTERNAL           SELECT
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGEESX computes for an N-by-N real nonsymmetric matrix A, the
*> eigenvalues, the real Schur form T, and, optionally, the matrix of
*> Schur vectors Z.  This gives the Schur factorization A = Z*T*(Z**T).
*>
*> Optionally, it also orders the eigenvalues on the diagonal of the
*> real Schur form so that selected eigenvalues are at the top left;
*> computes a reciprocal condition number for the average of the
*> selected eigenvalues (RCONDE); and computes a reciprocal condition
*> number for the right invariant subspace corresponding to the
*> selected eigenvalues (RCONDV).  The leading columns of Z form an
*> orthonormal basis for this invariant subspace.
*>
*> For further explanation of the reciprocal condition numbers RCONDE
*> and RCONDV, see Section 4.10 of the LAPACK Users' Guide (where
*> these quantities are called s and sep respectively).
*>
*> A real matrix is in real Schur form if it is upper quasi-triangular
*> with 1-by-1 and 2-by-2 blocks. 2-by-2 blocks will be standardized in
*> the form
*>           [  a  b  ]
*>           [  c  a  ]
*>
*> where b*c < 0. The eigenvalues of such a block are a +- sqrt(bc).
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] JOBVS
*> \verbatim
*>          JOBVS is CHARACTER*1
*>          = 'N': Schur vectors are not computed;
*>          = 'V': Schur vectors are computed.
*> \endverbatim
*>
*> \param[in] SORT
*> \verbatim
*>          SORT is CHARACTER*1
*>          Specifies whether or not to order the eigenvalues on the
*>          diagonal of the Schur form.
*>          = 'N': Eigenvalues are not ordered;
*>          = 'S': Eigenvalues are ordered (see SELECT).
*> \endverbatim
*>
*> \param[in] SELECT
*> \verbatim
*>          SELECT is a LOGICAL FUNCTION of two DOUBLE PRECISION arguments
*>          SELECT must be declared EXTERNAL in the calling subroutine.
*>          If SORT = 'S', SELECT is used to select eigenvalues to sort
*>          to the top left of the Schur form.
*>          If SORT = 'N', SELECT is not referenced.
*>          An eigenvalue WR(j)+sqrt(-1)*WI(j) is selected if
*>          SELECT(WR(j),WI(j)) is true; i.e., if either one of a
*>          complex conjugate pair of eigenvalues is selected, then both
*>          are.  Note that a selected complex eigenvalue may no longer
*>          satisfy SELECT(WR(j),WI(j)) = .TRUE. after ordering, since
*>          ordering may change the value of complex eigenvalues
*>          (especially if the eigenvalue is ill-conditioned); in this
*>          case INFO may be set to N+3 (see INFO below).
*> \endverbatim
*>
*> \param[in] SENSE
*> \verbatim
*>          SENSE is CHARACTER*1
*>          Determines which reciprocal condition numbers are computed.
*>          = 'N': None are computed;
*>          = 'E': Computed for average of selected eigenvalues only;
*>          = 'V': Computed for selected right invariant subspace only;
*>          = 'B': Computed for both.
*>          If SENSE = 'E', 'V' or 'B', SORT must equal 'S'.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The order of the matrix A. N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA, N)
*>          On entry, the N-by-N matrix A.
*>          On exit, A is overwritten by its real Schur form T.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,N).
*> \endverbatim
*>
*> \param[out] SDIM
*> \verbatim
*>          SDIM is INTEGER
*>          If SORT = 'N', SDIM = 0.
*>          If SORT = 'S', SDIM = number of eigenvalues (after sorting)
*>                         for which SELECT is true. (Complex conjugate
*>                         pairs for which SELECT is true for either
*>                         eigenvalue count as 2.)
*> \endverbatim
*>
*> \param[out] WR
*> \verbatim
*>          WR is DOUBLE PRECISION array, dimension (N)
*> \endverbatim
*>
*> \param[out] WI
*> \verbatim
*>          WI is DOUBLE PRECISION array, dimension (N)
*>          WR and WI contain the real and imaginary parts, respectively,
*>          of the computed eigenvalues, in the same order that they
*>          appear on the diagonal of the output Schur form T.  Complex
*>          conjugate pairs of eigenvalues appear consecutively with the
*>          eigenvalue having the positive imaginary part first.
*> \endverbatim
*>
*> \param[out] VS
*> \verbatim
*>          VS is DOUBLE PRECISION array, dimension (LDVS,N)
*>          If JOBVS = 'V', VS contains the orthogonal matrix Z of Schur
*>          vectors.
*>          If JOBVS = 'N', VS is not referenced.
*> \endverbatim
*>
*> \param[in] LDVS
*> \verbatim
*>          LDVS is INTEGER
*>          The leading dimension of the array VS.  LDVS >= 1, and if
*>          JOBVS = 'V', LDVS >= N.
*> \endverbatim
*>
*> \param[out] RCONDE
*> \verbatim
*>          RCONDE is DOUBLE PRECISION
*>          If SENSE = 'E' or 'B', RCONDE contains the reciprocal
*>          condition number for the average of the selected eigenvalues.
*>          Not referenced if SENSE = 'N' or 'V'.
*> \endverbatim
*>
*> \param[out] RCONDV
*> \verbatim
*>          RCONDV is DOUBLE PRECISION
*>          If SENSE = 'V' or 'B', RCONDV contains the reciprocal
*>          condition number for the selected right invariant subspace.
*>          Not referenced if SENSE = 'N' or 'E'.
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK))
*>          On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
*> \endverbatim
*>
*> \param[in] LWORK
*> \verbatim
*>          LWORK is INTEGER
*>          The dimension of the array WORK.  LWORK >= max(1,3*N).
*>          Also, if SENSE = 'E' or 'V' or 'B',
*>          LWORK >= N+2*SDIM*(N-SDIM), where SDIM is the number of
*>          selected eigenvalues computed by this routine.  Note that
*>          N+2*SDIM*(N-SDIM) <= N+N*N/2. Note also that an error is only
*>          returned if LWORK < max(1,3*N), but if SENSE = 'E' or 'V' or
*>          'B' this may not be large enough.
*>          For good performance, LWORK must generally be larger.
*>
*>          If LWORK = -1, then a workspace query is assumed; the routine
*>          only calculates upper bounds on the optimal sizes of the
*>          arrays WORK and IWORK, returns these values as the first
*>          entries of the WORK and IWORK arrays, and no error messages
*>          related to LWORK or LIWORK are issued by XERBLA.
*> \endverbatim
*>
*> \param[out] IWORK
*> \verbatim
*>          IWORK is INTEGER array, dimension (MAX(1,LIWORK))
*>          On exit, if INFO = 0, IWORK(1) returns the optimal LIWORK.
*> \endverbatim
*>
*> \param[in] LIWORK
*> \verbatim
*>          LIWORK is INTEGER
*>          The dimension of the array IWORK.
*>          LIWORK >= 1; if SENSE = 'V' or 'B', LIWORK >= SDIM*(N-SDIM).
*>          Note that SDIM*(N-SDIM) <= N*N/4. Note also that an error is
*>          only returned if LIWORK < 1, but if SENSE = 'V' or 'B' this
*>          may not be large enough.
*>
*>          If LIWORK = -1, then a workspace query is assumed; the
*>          routine only calculates upper bounds on the optimal sizes of
*>          the arrays WORK and IWORK, returns these values as the first
*>          entries of the WORK and IWORK arrays, and no error messages
*>          related to LWORK or LIWORK are issued by XERBLA.
*> \endverbatim
*>
*> \param[out] BWORK
*> \verbatim
*>          BWORK is LOGICAL array, dimension (N)
*>          Not referenced if SORT = 'N'.
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0: successful exit
*>          < 0: if INFO = -i, the i-th argument had an illegal value.
*>          > 0: if INFO = i, and i is
*>             <= N: the QR algorithm failed to compute all the
*>                   eigenvalues; elements 1:ILO-1 and i+1:N of WR and WI
*>                   contain those eigenvalues which have converged; if
*>                   JOBVS = 'V', VS contains the transformation which
*>                   reduces A to its partially converged Schur form.
*>             = N+1: the eigenvalues could not be reordered because some
*>                   eigenvalues were too close to separate (the problem
*>                   is very ill-conditioned);
*>             = N+2: after reordering, roundoff changed values of some
*>                   complex eigenvalues so that leading eigenvalues in
*>                   the Schur form no longer satisfy SELECT=.TRUE.  This
*>                   could also be caused by underflow due to scaling.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date June 2016
*
*> \ingroup doubleGEeigen
*
*  =====================================================================
      SUBROUTINE DGEESX( JOBVS, SORT, SELECT, SENSE, N, A, LDA, SDIM,
     $                   WR, WI, VS, LDVS, RCONDE, RCONDV, WORK, LWORK,
     $                   IWORK, LIWORK, BWORK, INFO )
*
*  -- LAPACK driver routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     June 2016
*
*     .. Scalar Arguments ..
      CHARACTER          JOBVS, SENSE, SORT
      INTEGER            INFO, LDA, LDVS, LIWORK, LWORK, N, SDIM
      DOUBLE PRECISION   RCONDE, RCONDV
*     ..
*     .. Array Arguments ..
      LOGICAL            BWORK( * )
      INTEGER            IWORK( * )
      DOUBLE PRECISION   A( LDA, * ), VS( LDVS, * ), WI( * ), WORK( * ),
     $                   WR( * )
*     ..
*     .. Function Arguments ..
      LOGICAL            SELECT
      EXTERNAL           SELECT
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ZERO, ONE
      PARAMETER          ( ZERO = 0.0D0, ONE = 1.0D0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            CURSL, LASTSL, LQUERY, LST2SL, SCALEA, WANTSB,
     $                   WANTSE, WANTSN, WANTST, WANTSV, WANTVS
      INTEGER            HSWORK, I, I1, I2, IBAL, ICOND, IERR, IEVAL,
     $                   IHI, ILO, INXT, IP, ITAU, IWRK, LIWRK, LWRK,
     $                   MAXWRK, MINWRK
      DOUBLE PRECISION   ANRM, BIGNUM, CSCALE, EPS, SMLNUM
*     ..
*     .. Local Arrays ..
      DOUBLE PRECISION   DUM( 1 )
*     ..
*     .. External Subroutines ..
      EXTERNAL           DCOPY, DGEBAK, DGEBAL, DGEHRD, DHSEQR, DLACPY,
     $                   DLASCL, DORGHR, DSWAP, DTRSEN, XERBLA
*     ..
*     .. External Functions ..
      LOGICAL            LSAME
      INTEGER            ILAENV
      DOUBLE PRECISION   DLAMCH, DLANGE
      EXTERNAL           LSAME, ILAENV, DLABAD, DLAMCH, DLANGE
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, SQRT
*     ..
*     .. Executable Statements ..
*
*     Test the input arguments
*
      INFO = 0
      WANTVS = LSAME( JOBVS, 'V' )
      WANTST = LSAME( SORT, 'S' )
      WANTSN = LSAME( SENSE, 'N' )
      WANTSE = LSAME( SENSE, 'E' )
      WANTSV = LSAME( SENSE, 'V' )
      WANTSB = LSAME( SENSE, 'B' )
      LQUERY = ( LWORK.EQ.-1 .OR. LIWORK.EQ.-1 )
*
      IF( ( .NOT.WANTVS ) .AND. ( .NOT.LSAME( JOBVS, 'N' ) ) ) THEN
         INFO = -1
      ELSE IF( ( .NOT.WANTST ) .AND. ( .NOT.LSAME( SORT, 'N' ) ) ) THEN
         INFO = -2
      ELSE IF( .NOT.( WANTSN .OR. WANTSE .OR. WANTSV .OR. WANTSB ) .OR.
     $         ( .NOT.WANTST .AND. .NOT.WANTSN ) ) THEN
         INFO = -4
      ELSE IF( N.LT.0 ) THEN
         INFO = -5
      ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
         INFO = -7
      ELSE IF( LDVS.LT.1 .OR. ( WANTVS .AND. LDVS.LT.N ) ) THEN
         INFO = -12
      END IF
*
*     Compute workspace
*      (Note: Comments in the code beginning "RWorkspace:" describe the
*       minimal amount of real workspace needed at that point in the
*       code, as well as the preferred amount for good performance.
*       IWorkspace refers to integer workspace.
*       NB refers to the optimal block size for the immediately
*       following subroutine, as returned by ILAENV.
*       HSWORK refers to the workspace preferred by DHSEQR, as
*       calculated below. HSWORK is computed assuming ILO=1 and IHI=N,
*       the worst case.
*       If SENSE = 'E', 'V' or 'B', then the amount of workspace needed
*       depends on SDIM, which is computed by the routine DTRSEN later
*       in the code.)
*
      IF( INFO.EQ.0 ) THEN
         LIWRK = 1
         IF( N.EQ.0 ) THEN
            MINWRK = 1
            LWRK = 1
         ELSE
            MAXWRK = 2*N + N*ILAENV( 1, 'DGEHRD', ' ', N, 1, N, 0 )
            MINWRK = 3*N
*
            CALL DHSEQR( 'S', JOBVS, N, 1, N, A, LDA, WR, WI, VS, LDVS,
     $             WORK, -1, IEVAL )
            HSWORK = WORK( 1 )
*
            IF( .NOT.WANTVS ) THEN
               MAXWRK = MAX( MAXWRK, N + HSWORK )
            ELSE
               MAXWRK = MAX( MAXWRK, 2*N + ( N - 1 )*ILAENV( 1,
     $                       'DORGHR', ' ', N, 1, N, -1 ) )
               MAXWRK = MAX( MAXWRK, N + HSWORK )
            END IF
            LWRK = MAXWRK
            IF( .NOT.WANTSN )
     $         LWRK = MAX( LWRK, N + ( N*N )/2 )
            IF( WANTSV .OR. WANTSB )
     $         LIWRK = ( N*N )/4
         END IF
         IWORK( 1 ) = LIWRK
         WORK( 1 ) = LWRK
*
         IF( LWORK.LT.MINWRK .AND. .NOT.LQUERY ) THEN
            INFO = -16
         ELSE IF( LIWORK.LT.1 .AND. .NOT.LQUERY ) THEN
            INFO = -18
         END IF
      END IF
*
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGEESX', -INFO )
         RETURN
      ELSE IF( LQUERY ) THEN
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( N.EQ.0 ) THEN
         SDIM = 0
         RETURN
      END IF
*
*     Get machine constants
*
      EPS = DLAMCH( 'P' )
      SMLNUM = DLAMCH( 'S' )
      BIGNUM = ONE / SMLNUM
      CALL DLABAD( SMLNUM, BIGNUM )
      SMLNUM = SQRT( SMLNUM ) / EPS
      BIGNUM = ONE / SMLNUM
*
*     Scale A if max element outside range [SMLNUM,BIGNUM]
*
      ANRM = DLANGE( 'M', N, N, A, LDA, DUM )
      SCALEA = .FALSE.
      IF( ANRM.GT.ZERO .AND. ANRM.LT.SMLNUM ) THEN
         SCALEA = .TRUE.
         CSCALE = SMLNUM
      ELSE IF( ANRM.GT.BIGNUM ) THEN
         SCALEA = .TRUE.
         CSCALE = BIGNUM
      END IF
      IF( SCALEA )
     $   CALL DLASCL( 'G', 0, 0, ANRM, CSCALE, N, N, A, LDA, IERR )
*
*     Permute the matrix to make it more nearly triangular
*     (RWorkspace: need N)
*
      IBAL = 1
      CALL DGEBAL( 'P', N, A, LDA, ILO, IHI, WORK( IBAL ), IERR )
*
*     Reduce to upper Hessenberg form
*     (RWorkspace: need 3*N, prefer 2*N+N*NB)
*
      ITAU = N + IBAL
      IWRK = N + ITAU
      CALL DGEHRD( N, ILO, IHI, A, LDA, WORK( ITAU ), WORK( IWRK ),
     $             LWORK-IWRK+1, IERR )
*
      IF( WANTVS ) THEN
*
*        Copy Householder vectors to VS
*
         CALL DLACPY( 'L', N, N, A, LDA, VS, LDVS )
*
*        Generate orthogonal matrix in VS
*        (RWorkspace: need 3*N-1, prefer 2*N+(N-1)*NB)
*
         CALL DORGHR( N, ILO, IHI, VS, LDVS, WORK( ITAU ), WORK( IWRK ),
     $                LWORK-IWRK+1, IERR )
      END IF
*
      SDIM = 0
*
*     Perform QR iteration, accumulating Schur vectors in VS if desired
*     (RWorkspace: need N+1, prefer N+HSWORK (see comments) )
*
      IWRK = ITAU
      CALL DHSEQR( 'S', JOBVS, N, ILO, IHI, A, LDA, WR, WI, VS, LDVS,
     $             WORK( IWRK ), LWORK-IWRK+1, IEVAL )
      IF( IEVAL.GT.0 )
     $   INFO = IEVAL
*
*     Sort eigenvalues if desired
*
      IF( WANTST .AND. INFO.EQ.0 ) THEN
         IF( SCALEA ) THEN
            CALL DLASCL( 'G', 0, 0, CSCALE, ANRM, N, 1, WR, N, IERR )
            CALL DLASCL( 'G', 0, 0, CSCALE, ANRM, N, 1, WI, N, IERR )
         END IF
         DO 10 I = 1, N
            BWORK( I ) = SELECT( WR( I ), WI( I ) )
   10    CONTINUE
*
*        Reorder eigenvalues, transform Schur vectors, and compute
*        reciprocal condition numbers
*        (RWorkspace: if SENSE is not 'N', need N+2*SDIM*(N-SDIM)
*                     otherwise, need N )
*        (IWorkspace: if SENSE is 'V' or 'B', need SDIM*(N-SDIM)
*                     otherwise, need 0 )
*
         CALL DTRSEN( SENSE, JOBVS, BWORK, N, A, LDA, VS, LDVS, WR, WI,
     $                SDIM, RCONDE, RCONDV, WORK( IWRK ), LWORK-IWRK+1,
     $                IWORK, LIWORK, ICOND )
         IF( .NOT.WANTSN )
     $      MAXWRK = MAX( MAXWRK, N+2*SDIM*( N-SDIM ) )
         IF( ICOND.EQ.-15 ) THEN
*
*           Not enough real workspace
*
            INFO = -16
         ELSE IF( ICOND.EQ.-17 ) THEN
*
*           Not enough integer workspace
*
            INFO = -18
         ELSE IF( ICOND.GT.0 ) THEN
*
*           DTRSEN failed to reorder or to restore standard Schur form
*
            INFO = ICOND + N
         END IF
      END IF
*
      IF( WANTVS ) THEN
*
*        Undo balancing
*        (RWorkspace: need N)
*
         CALL DGEBAK( 'P', 'R', N, ILO, IHI, WORK( IBAL ), N, VS, LDVS,
     $                IERR )
      END IF
*
      IF( SCALEA ) THEN
*
*        Undo scaling for the Schur form of A
*
         CALL DLASCL( 'H', 0, 0, CSCALE, ANRM, N, N, A, LDA, IERR )
         CALL DCOPY( N, A, LDA+1, WR, 1 )
         IF( ( WANTSV .OR. WANTSB ) .AND. INFO.EQ.0 ) THEN
            DUM( 1 ) = RCONDV
            CALL DLASCL( 'G', 0, 0, CSCALE, ANRM, 1, 1, DUM, 1, IERR )
            RCONDV = DUM( 1 )
         END IF
         IF( CSCALE.EQ.SMLNUM ) THEN
*
*           If scaling back towards underflow, adjust WI if an
*           offdiagonal element of a 2-by-2 block in the Schur form
*           underflows.
*
            IF( IEVAL.GT.0 ) THEN
               I1 = IEVAL + 1
               I2 = IHI - 1
               CALL DLASCL( 'G', 0, 0, CSCALE, ANRM, ILO-1, 1, WI, N,
     $                      IERR )
            ELSE IF( WANTST ) THEN
               I1 = 1
               I2 = N - 1
            ELSE
               I1 = ILO
               I2 = IHI - 1
            END IF
            INXT = I1 - 1
            DO 20 I = I1, I2
               IF( I.LT.INXT )
     $            GO TO 20
               IF( WI( I ).EQ.ZERO ) THEN
                  INXT = I + 1
               ELSE
                  IF( A( I+1, I ).EQ.ZERO ) THEN
                     WI( I ) = ZERO
                     WI( I+1 ) = ZERO
                  ELSE IF( A( I+1, I ).NE.ZERO .AND. A( I, I+1 ).EQ.
     $                     ZERO ) THEN
                     WI( I ) = ZERO
                     WI( I+1 ) = ZERO
                     IF( I.GT.1 )
     $                  CALL DSWAP( I-1, A( 1, I ), 1, A( 1, I+1 ), 1 )
                     IF( N.GT.I+1 )
     $                  CALL DSWAP( N-I-1, A( I, I+2 ), LDA,
     $                              A( I+1, I+2 ), LDA )
                     CALL DSWAP( N, VS( 1, I ), 1, VS( 1, I+1 ), 1 )
                     A( I, I+1 ) = A( I+1, I )
                     A( I+1, I ) = ZERO
                  END IF
                  INXT = I + 2
               END IF
   20       CONTINUE
         END IF
         CALL DLASCL( 'G', 0, 0, CSCALE, ANRM, N-IEVAL, 1,
     $                WI( IEVAL+1 ), MAX( N-IEVAL, 1 ), IERR )
      END IF
*
      IF( WANTST .AND. INFO.EQ.0 ) THEN
*
*        Check if reordering successful
*
         LASTSL = .TRUE.
         LST2SL = .TRUE.
         SDIM = 0
         IP = 0
         DO 30 I = 1, N
            CURSL = SELECT( WR( I ), WI( I ) )
            IF( WI( I ).EQ.ZERO ) THEN
               IF( CURSL )
     $            SDIM = SDIM + 1
               IP = 0
               IF( CURSL .AND. .NOT.LASTSL )
     $            INFO = N + 2
            ELSE
               IF( IP.EQ.1 ) THEN
*
*                 Last eigenvalue of conjugate pair
*
                  CURSL = CURSL .OR. LASTSL
                  LASTSL = CURSL
                  IF( CURSL )
     $               SDIM = SDIM + 2
                  IP = -1
                  IF( CURSL .AND. .NOT.LST2SL )
     $               INFO = N + 2
               ELSE
*
*                 First eigenvalue of conjugate pair
*
                  IP = 1
               END IF
            END IF
            LST2SL = LASTSL
            LASTSL = CURSL
   30    CONTINUE
      END IF
*
      WORK( 1 ) = MAXWRK
      IF( WANTSV .OR. WANTSB ) THEN
         IWORK( 1 ) = MAX( 1, SDIM*( N-SDIM ) )
      ELSE
         IWORK( 1 ) = 1
      END IF
*
      RETURN
*
*     End of DGEESX
*
      END
*> \brief <b> DGEEV computes the eigenvalues and, optionally, the left and/or right eigenvectors for GE matrices</b>
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGEEV + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgeev.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgeev.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgeev.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGEEV( JOBVL, JOBVR, N, A, LDA, WR, WI, VL, LDVL, VR,
*                         LDVR, WORK, LWORK, INFO )
*
*       .. Scalar Arguments ..
*       CHARACTER          JOBVL, JOBVR
*       INTEGER            INFO, LDA, LDVL, LDVR, LWORK, N
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   A( LDA, * ), VL( LDVL, * ), VR( LDVR, * ),
*      $                   WI( * ), WORK( * ), WR( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGEEV computes for an N-by-N real nonsymmetric matrix A, the
*> eigenvalues and, optionally, the left and/or right eigenvectors.
*>
*> The right eigenvector v(j) of A satisfies
*>                  A * v(j) = lambda(j) * v(j)
*> where lambda(j) is its eigenvalue.
*> The left eigenvector u(j) of A satisfies
*>               u(j)**H * A = lambda(j) * u(j)**H
*> where u(j)**H denotes the conjugate-transpose of u(j).
*>
*> The computed eigenvectors are normalized to have Euclidean norm
*> equal to 1 and largest component real.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] JOBVL
*> \verbatim
*>          JOBVL is CHARACTER*1
*>          = 'N': left eigenvectors of A are not computed;
*>          = 'V': left eigenvectors of A are computed.
*> \endverbatim
*>
*> \param[in] JOBVR
*> \verbatim
*>          JOBVR is CHARACTER*1
*>          = 'N': right eigenvectors of A are not computed;
*>          = 'V': right eigenvectors of A are computed.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The order of the matrix A. N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the N-by-N matrix A.
*>          On exit, A has been overwritten.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,N).
*> \endverbatim
*>
*> \param[out] WR
*> \verbatim
*>          WR is DOUBLE PRECISION array, dimension (N)
*> \endverbatim
*>
*> \param[out] WI
*> \verbatim
*>          WI is DOUBLE PRECISION array, dimension (N)
*>          WR and WI contain the real and imaginary parts,
*>          respectively, of the computed eigenvalues.  Complex
*>          conjugate pairs of eigenvalues appear consecutively
*>          with the eigenvalue having the positive imaginary part
*>          first.
*> \endverbatim
*>
*> \param[out] VL
*> \verbatim
*>          VL is DOUBLE PRECISION array, dimension (LDVL,N)
*>          If JOBVL = 'V', the left eigenvectors u(j) are stored one
*>          after another in the columns of VL, in the same order
*>          as their eigenvalues.
*>          If JOBVL = 'N', VL is not referenced.
*>          If the j-th eigenvalue is real, then u(j) = VL(:,j),
*>          the j-th column of VL.
*>          If the j-th and (j+1)-st eigenvalues form a complex
*>          conjugate pair, then u(j) = VL(:,j) + i*VL(:,j+1) and
*>          u(j+1) = VL(:,j) - i*VL(:,j+1).
*> \endverbatim
*>
*> \param[in] LDVL
*> \verbatim
*>          LDVL is INTEGER
*>          The leading dimension of the array VL.  LDVL >= 1; if
*>          JOBVL = 'V', LDVL >= N.
*> \endverbatim
*>
*> \param[out] VR
*> \verbatim
*>          VR is DOUBLE PRECISION array, dimension (LDVR,N)
*>          If JOBVR = 'V', the right eigenvectors v(j) are stored one
*>          after another in the columns of VR, in the same order
*>          as their eigenvalues.
*>          If JOBVR = 'N', VR is not referenced.
*>          If the j-th eigenvalue is real, then v(j) = VR(:,j),
*>          the j-th column of VR.
*>          If the j-th and (j+1)-st eigenvalues form a complex
*>          conjugate pair, then v(j) = VR(:,j) + i*VR(:,j+1) and
*>          v(j+1) = VR(:,j) - i*VR(:,j+1).
*> \endverbatim
*>
*> \param[in] LDVR
*> \verbatim
*>          LDVR is INTEGER
*>          The leading dimension of the array VR.  LDVR >= 1; if
*>          JOBVR = 'V', LDVR >= N.
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK))
*>          On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
*> \endverbatim
*>
*> \param[in] LWORK
*> \verbatim
*>          LWORK is INTEGER
*>          The dimension of the array WORK.  LWORK >= max(1,3*N), and
*>          if JOBVL = 'V' or JOBVR = 'V', LWORK >= 4*N.  For good
*>          performance, LWORK must generally be larger.
*>
*>          If LWORK = -1, then a workspace query is assumed; the routine
*>          only calculates the optimal size of the WORK array, returns
*>          this value as the first entry of the WORK array, and no error
*>          message related to LWORK is issued by XERBLA.
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value.
*>          > 0:  if INFO = i, the QR algorithm failed to compute all the
*>                eigenvalues, and no eigenvectors have been computed;
*>                elements i+1:N of WR and WI contain eigenvalues which
*>                have converged.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date June 2016
*
*  @precisions fortran d -> s
*
*> \ingroup doubleGEeigen
*
*  =====================================================================
      SUBROUTINE DGEEV( JOBVL, JOBVR, N, A, LDA, WR, WI, VL, LDVL, VR,
     $                  LDVR, WORK, LWORK, INFO )
      implicit none
*
*  -- LAPACK driver routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     June 2016
*
*     .. Scalar Arguments ..
      CHARACTER          JOBVL, JOBVR
      INTEGER            INFO, LDA, LDVL, LDVR, LWORK, N
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   A( LDA, * ), VL( LDVL, * ), VR( LDVR, * ),
     $                   WI( * ), WORK( * ), WR( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ZERO, ONE
      PARAMETER          ( ZERO = 0.0D0, ONE = 1.0D0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            LQUERY, SCALEA, WANTVL, WANTVR
      CHARACTER          SIDE
      INTEGER            HSWORK, I, IBAL, IERR, IHI, ILO, ITAU, IWRK, K,
     $                   LWORK_TREVC, MAXWRK, MINWRK, NOUT
      DOUBLE PRECISION   ANRM, BIGNUM, CS, CSCALE, EPS, R, SCL, SMLNUM,
     $                   SN
*     ..
*     .. Local Arrays ..
      LOGICAL            SELECT( 1 )
      DOUBLE PRECISION   DUM( 1 )
*     ..
*     .. External Subroutines ..
      EXTERNAL           DGEBAK, DGEBAL, DGEHRD, DHSEQR, DLABAD, DLACPY,
     $                   DLARTG, DLASCL, DORGHR, DROT, DSCAL, DTREVC3,
     $                   XERBLA
*     ..
*     .. External Functions ..
      LOGICAL            LSAME
      INTEGER            IDAMAX, ILAENV
      DOUBLE PRECISION   DLAMCH, DLANGE, DLAPY2, DNRM2
      EXTERNAL           LSAME, IDAMAX, ILAENV, DLAMCH, DLANGE, DLAPY2,
     $                   DNRM2
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, SQRT
*     ..
*     .. Executable Statements ..
*
*     Test the input arguments
*
      INFO = 0
      LQUERY = ( LWORK.EQ.-1 )
      WANTVL = LSAME( JOBVL, 'V' )
      WANTVR = LSAME( JOBVR, 'V' )
      IF( ( .NOT.WANTVL ) .AND. ( .NOT.LSAME( JOBVL, 'N' ) ) ) THEN
         INFO = -1
      ELSE IF( ( .NOT.WANTVR ) .AND. ( .NOT.LSAME( JOBVR, 'N' ) ) ) THEN
         INFO = -2
      ELSE IF( N.LT.0 ) THEN
         INFO = -3
      ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
         INFO = -5
      ELSE IF( LDVL.LT.1 .OR. ( WANTVL .AND. LDVL.LT.N ) ) THEN
         INFO = -9
      ELSE IF( LDVR.LT.1 .OR. ( WANTVR .AND. LDVR.LT.N ) ) THEN
         INFO = -11
      END IF
*
*     Compute workspace
*      (Note: Comments in the code beginning "Workspace:" describe the
*       minimal amount of workspace needed at that point in the code,
*       as well as the preferred amount for good performance.
*       NB refers to the optimal block size for the immediately
*       following subroutine, as returned by ILAENV.
*       HSWORK refers to the workspace preferred by DHSEQR, as
*       calculated below. HSWORK is computed assuming ILO=1 and IHI=N,
*       the worst case.)
*
      IF( INFO.EQ.0 ) THEN
         IF( N.EQ.0 ) THEN
            MINWRK = 1
            MAXWRK = 1
         ELSE
            MAXWRK = 2*N + N*ILAENV( 1, 'DGEHRD', ' ', N, 1, N, 0 )
            IF( WANTVL ) THEN
               MINWRK = 4*N
               MAXWRK = MAX( MAXWRK, 2*N + ( N - 1 )*ILAENV( 1,
     $                       'DORGHR', ' ', N, 1, N, -1 ) )
               CALL DHSEQR( 'S', 'V', N, 1, N, A, LDA, WR, WI, VL, LDVL,
     $                      WORK, -1, INFO )
               HSWORK = INT( WORK(1) )
               MAXWRK = MAX( MAXWRK, N + 1, N + HSWORK )
               CALL DTREVC3( 'L', 'B', SELECT, N, A, LDA,
     $                       VL, LDVL, VR, LDVR, N, NOUT,
     $                       WORK, -1, IERR )
               LWORK_TREVC = INT( WORK(1) )
               MAXWRK = MAX( MAXWRK, N + LWORK_TREVC )
               MAXWRK = MAX( MAXWRK, 4*N )
            ELSE IF( WANTVR ) THEN
               MINWRK = 4*N
               MAXWRK = MAX( MAXWRK, 2*N + ( N - 1 )*ILAENV( 1,
     $                       'DORGHR', ' ', N, 1, N, -1 ) )
               CALL DHSEQR( 'S', 'V', N, 1, N, A, LDA, WR, WI, VR, LDVR,
     $                      WORK, -1, INFO )
               HSWORK = INT( WORK(1) )
               MAXWRK = MAX( MAXWRK, N + 1, N + HSWORK )
               CALL DTREVC3( 'R', 'B', SELECT, N, A, LDA,
     $                       VL, LDVL, VR, LDVR, N, NOUT,
     $                       WORK, -1, IERR )
               LWORK_TREVC = INT( WORK(1) )
               MAXWRK = MAX( MAXWRK, N + LWORK_TREVC )
               MAXWRK = MAX( MAXWRK, 4*N )
            ELSE
               MINWRK = 3*N
               CALL DHSEQR( 'E', 'N', N, 1, N, A, LDA, WR, WI, VR, LDVR,
     $                      WORK, -1, INFO )
               HSWORK = INT( WORK(1) )
               MAXWRK = MAX( MAXWRK, N + 1, N + HSWORK )
            END IF
            MAXWRK = MAX( MAXWRK, MINWRK )
         END IF
         WORK( 1 ) = MAXWRK
*
         IF( LWORK.LT.MINWRK .AND. .NOT.LQUERY ) THEN
            INFO = -13
         END IF
      END IF
*
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGEEV ', -INFO )
         RETURN
      ELSE IF( LQUERY ) THEN
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( N.EQ.0 )
     $   RETURN
*
*     Get machine constants
*
      EPS = DLAMCH( 'P' )
      SMLNUM = DLAMCH( 'S' )
      BIGNUM = ONE / SMLNUM
      CALL DLABAD( SMLNUM, BIGNUM )
      SMLNUM = SQRT( SMLNUM ) / EPS
      BIGNUM = ONE / SMLNUM
*
*     Scale A if max element outside range [SMLNUM,BIGNUM]
*
      ANRM = DLANGE( 'M', N, N, A, LDA, DUM )
      SCALEA = .FALSE.
      IF( ANRM.GT.ZERO .AND. ANRM.LT.SMLNUM ) THEN
         SCALEA = .TRUE.
         CSCALE = SMLNUM
      ELSE IF( ANRM.GT.BIGNUM ) THEN
         SCALEA = .TRUE.
         CSCALE = BIGNUM
      END IF
      IF( SCALEA )
     $   CALL DLASCL( 'G', 0, 0, ANRM, CSCALE, N, N, A, LDA, IERR )
*
*     Balance the matrix
*     (Workspace: need N)
*
      IBAL = 1
      CALL DGEBAL( 'B', N, A, LDA, ILO, IHI, WORK( IBAL ), IERR )
*
*     Reduce to upper Hessenberg form
*     (Workspace: need 3*N, prefer 2*N+N*NB)
*
      ITAU = IBAL + N
      IWRK = ITAU + N
      CALL DGEHRD( N, ILO, IHI, A, LDA, WORK( ITAU ), WORK( IWRK ),
     $             LWORK-IWRK+1, IERR )
*
      IF( WANTVL ) THEN
*
*        Want left eigenvectors
*        Copy Householder vectors to VL
*
         SIDE = 'L'
         CALL DLACPY( 'L', N, N, A, LDA, VL, LDVL )
*
*        Generate orthogonal matrix in VL
*        (Workspace: need 3*N-1, prefer 2*N+(N-1)*NB)
*
         CALL DORGHR( N, ILO, IHI, VL, LDVL, WORK( ITAU ), WORK( IWRK ),
     $                LWORK-IWRK+1, IERR )
*
*        Perform QR iteration, accumulating Schur vectors in VL
*        (Workspace: need N+1, prefer N+HSWORK (see comments) )
*
         IWRK = ITAU
         CALL DHSEQR( 'S', 'V', N, ILO, IHI, A, LDA, WR, WI, VL, LDVL,
     $                WORK( IWRK ), LWORK-IWRK+1, INFO )
*
         IF( WANTVR ) THEN
*
*           Want left and right eigenvectors
*           Copy Schur vectors to VR
*
            SIDE = 'B'
            CALL DLACPY( 'F', N, N, VL, LDVL, VR, LDVR )
         END IF
*
      ELSE IF( WANTVR ) THEN
*
*        Want right eigenvectors
*        Copy Householder vectors to VR
*
         SIDE = 'R'
         CALL DLACPY( 'L', N, N, A, LDA, VR, LDVR )
*
*        Generate orthogonal matrix in VR
*        (Workspace: need 3*N-1, prefer 2*N+(N-1)*NB)
*
         CALL DORGHR( N, ILO, IHI, VR, LDVR, WORK( ITAU ), WORK( IWRK ),
     $                LWORK-IWRK+1, IERR )
*
*        Perform QR iteration, accumulating Schur vectors in VR
*        (Workspace: need N+1, prefer N+HSWORK (see comments) )
*
         IWRK = ITAU
         CALL DHSEQR( 'S', 'V', N, ILO, IHI, A, LDA, WR, WI, VR, LDVR,
     $                WORK( IWRK ), LWORK-IWRK+1, INFO )
*
      ELSE
*
*        Compute eigenvalues only
*        (Workspace: need N+1, prefer N+HSWORK (see comments) )
*
         IWRK = ITAU
         CALL DHSEQR( 'E', 'N', N, ILO, IHI, A, LDA, WR, WI, VR, LDVR,
     $                WORK( IWRK ), LWORK-IWRK+1, INFO )
      END IF
*
*     If INFO .NE. 0 from DHSEQR, then quit
*
      IF( INFO.NE.0 )
     $   GO TO 50
*
      IF( WANTVL .OR. WANTVR ) THEN
*
*        Compute left and/or right eigenvectors
*        (Workspace: need 4*N, prefer N + N + 2*N*NB)
*
         CALL DTREVC3( SIDE, 'B', SELECT, N, A, LDA, VL, LDVL, VR, LDVR,
     $                 N, NOUT, WORK( IWRK ), LWORK-IWRK+1, IERR )
      END IF
*
      IF( WANTVL ) THEN
*
*        Undo balancing of left eigenvectors
*        (Workspace: need N)
*
         CALL DGEBAK( 'B', 'L', N, ILO, IHI, WORK( IBAL ), N, VL, LDVL,
     $                IERR )
*
*        Normalize left eigenvectors and make largest component real
*
         DO 20 I = 1, N
            IF( WI( I ).EQ.ZERO ) THEN
               SCL = ONE / DNRM2( N, VL( 1, I ), 1 )
               CALL DSCAL( N, SCL, VL( 1, I ), 1 )
            ELSE IF( WI( I ).GT.ZERO ) THEN
               SCL = ONE / DLAPY2( DNRM2( N, VL( 1, I ), 1 ),
     $               DNRM2( N, VL( 1, I+1 ), 1 ) )
               CALL DSCAL( N, SCL, VL( 1, I ), 1 )
               CALL DSCAL( N, SCL, VL( 1, I+1 ), 1 )
               DO 10 K = 1, N
                  WORK( IWRK+K-1 ) = VL( K, I )**2 + VL( K, I+1 )**2
   10          CONTINUE
               K = IDAMAX( N, WORK( IWRK ), 1 )
               CALL DLARTG( VL( K, I ), VL( K, I+1 ), CS, SN, R )
               CALL DROT( N, VL( 1, I ), 1, VL( 1, I+1 ), 1, CS, SN )
               VL( K, I+1 ) = ZERO
            END IF
   20    CONTINUE
      END IF
*
      IF( WANTVR ) THEN
*
*        Undo balancing of right eigenvectors
*        (Workspace: need N)
*
         CALL DGEBAK( 'B', 'R', N, ILO, IHI, WORK( IBAL ), N, VR, LDVR,
     $                IERR )
*
*        Normalize right eigenvectors and make largest component real
*
         DO 40 I = 1, N
            IF( WI( I ).EQ.ZERO ) THEN
               SCL = ONE / DNRM2( N, VR( 1, I ), 1 )
               CALL DSCAL( N, SCL, VR( 1, I ), 1 )
            ELSE IF( WI( I ).GT.ZERO ) THEN
               SCL = ONE / DLAPY2( DNRM2( N, VR( 1, I ), 1 ),
     $               DNRM2( N, VR( 1, I+1 ), 1 ) )
               CALL DSCAL( N, SCL, VR( 1, I ), 1 )
               CALL DSCAL( N, SCL, VR( 1, I+1 ), 1 )
               DO 30 K = 1, N
                  WORK( IWRK+K-1 ) = VR( K, I )**2 + VR( K, I+1 )**2
   30          CONTINUE
               K = IDAMAX( N, WORK( IWRK ), 1 )
               CALL DLARTG( VR( K, I ), VR( K, I+1 ), CS, SN, R )
               CALL DROT( N, VR( 1, I ), 1, VR( 1, I+1 ), 1, CS, SN )
               VR( K, I+1 ) = ZERO
            END IF
   40    CONTINUE
      END IF
*
*     Undo scaling if necessary
*
   50 CONTINUE
      IF( SCALEA ) THEN
         CALL DLASCL( 'G', 0, 0, CSCALE, ANRM, N-INFO, 1, WR( INFO+1 ),
     $                MAX( N-INFO, 1 ), IERR )
         CALL DLASCL( 'G', 0, 0, CSCALE, ANRM, N-INFO, 1, WI( INFO+1 ),
     $                MAX( N-INFO, 1 ), IERR )
         IF( INFO.GT.0 ) THEN
            CALL DLASCL( 'G', 0, 0, CSCALE, ANRM, ILO-1, 1, WR, N,
     $                   IERR )
            CALL DLASCL( 'G', 0, 0, CSCALE, ANRM, ILO-1, 1, WI, N,
     $                   IERR )
         END IF
      END IF
*
      WORK( 1 ) = MAXWRK
      RETURN
*
*     End of DGEEV
*
      END
*> \brief <b> DGEEVX computes the eigenvalues and, optionally, the left and/or right eigenvectors for GE matrices</b>
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGEEVX + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgeevx.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgeevx.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgeevx.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGEEVX( BALANC, JOBVL, JOBVR, SENSE, N, A, LDA, WR, WI,
*                          VL, LDVL, VR, LDVR, ILO, IHI, SCALE, ABNRM,
*                          RCONDE, RCONDV, WORK, LWORK, IWORK, INFO )
*
*       .. Scalar Arguments ..
*       CHARACTER          BALANC, JOBVL, JOBVR, SENSE
*       INTEGER            IHI, ILO, INFO, LDA, LDVL, LDVR, LWORK, N
*       DOUBLE PRECISION   ABNRM
*       ..
*       .. Array Arguments ..
*       INTEGER            IWORK( * )
*       DOUBLE PRECISION   A( LDA, * ), RCONDE( * ), RCONDV( * ),
*      $                   SCALE( * ), VL( LDVL, * ), VR( LDVR, * ),
*      $                   WI( * ), WORK( * ), WR( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGEEVX computes for an N-by-N real nonsymmetric matrix A, the
*> eigenvalues and, optionally, the left and/or right eigenvectors.
*>
*> Optionally also, it computes a balancing transformation to improve
*> the conditioning of the eigenvalues and eigenvectors (ILO, IHI,
*> SCALE, and ABNRM), reciprocal condition numbers for the eigenvalues
*> (RCONDE), and reciprocal condition numbers for the right
*> eigenvectors (RCONDV).
*>
*> The right eigenvector v(j) of A satisfies
*>                  A * v(j) = lambda(j) * v(j)
*> where lambda(j) is its eigenvalue.
*> The left eigenvector u(j) of A satisfies
*>               u(j)**H * A = lambda(j) * u(j)**H
*> where u(j)**H denotes the conjugate-transpose of u(j).
*>
*> The computed eigenvectors are normalized to have Euclidean norm
*> equal to 1 and largest component real.
*>
*> Balancing a matrix means permuting the rows and columns to make it
*> more nearly upper triangular, and applying a diagonal similarity
*> transformation D * A * D**(-1), where D is a diagonal matrix, to
*> make its rows and columns closer in norm and the condition numbers
*> of its eigenvalues and eigenvectors smaller.  The computed
*> reciprocal condition numbers correspond to the balanced matrix.
*> Permuting rows and columns will not change the condition numbers
*> (in exact arithmetic) but diagonal scaling will.  For further
*> explanation of balancing, see section 4.10.2 of the LAPACK
*> Users' Guide.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] BALANC
*> \verbatim
*>          BALANC is CHARACTER*1
*>          Indicates how the input matrix should be diagonally scaled
*>          and/or permuted to improve the conditioning of its
*>          eigenvalues.
*>          = 'N': Do not diagonally scale or permute;
*>          = 'P': Perform permutations to make the matrix more nearly
*>                 upper triangular. Do not diagonally scale;
*>          = 'S': Diagonally scale the matrix, i.e. replace A by
*>                 D*A*D**(-1), where D is a diagonal matrix chosen
*>                 to make the rows and columns of A more equal in
*>                 norm. Do not permute;
*>          = 'B': Both diagonally scale and permute A.
*>
*>          Computed reciprocal condition numbers will be for the matrix
*>          after balancing and/or permuting. Permuting does not change
*>          condition numbers (in exact arithmetic), but balancing does.
*> \endverbatim
*>
*> \param[in] JOBVL
*> \verbatim
*>          JOBVL is CHARACTER*1
*>          = 'N': left eigenvectors of A are not computed;
*>          = 'V': left eigenvectors of A are computed.
*>          If SENSE = 'E' or 'B', JOBVL must = 'V'.
*> \endverbatim
*>
*> \param[in] JOBVR
*> \verbatim
*>          JOBVR is CHARACTER*1
*>          = 'N': right eigenvectors of A are not computed;
*>          = 'V': right eigenvectors of A are computed.
*>          If SENSE = 'E' or 'B', JOBVR must = 'V'.
*> \endverbatim
*>
*> \param[in] SENSE
*> \verbatim
*>          SENSE is CHARACTER*1
*>          Determines which reciprocal condition numbers are computed.
*>          = 'N': None are computed;
*>          = 'E': Computed for eigenvalues only;
*>          = 'V': Computed for right eigenvectors only;
*>          = 'B': Computed for eigenvalues and right eigenvectors.
*>
*>          If SENSE = 'E' or 'B', both left and right eigenvectors
*>          must also be computed (JOBVL = 'V' and JOBVR = 'V').
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The order of the matrix A. N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the N-by-N matrix A.
*>          On exit, A has been overwritten.  If JOBVL = 'V' or
*>          JOBVR = 'V', A contains the real Schur form of the balanced
*>          version of the input matrix A.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,N).
*> \endverbatim
*>
*> \param[out] WR
*> \verbatim
*>          WR is DOUBLE PRECISION array, dimension (N)
*> \endverbatim
*>
*> \param[out] WI
*> \verbatim
*>          WI is DOUBLE PRECISION array, dimension (N)
*>          WR and WI contain the real and imaginary parts,
*>          respectively, of the computed eigenvalues.  Complex
*>          conjugate pairs of eigenvalues will appear consecutively
*>          with the eigenvalue having the positive imaginary part
*>          first.
*> \endverbatim
*>
*> \param[out] VL
*> \verbatim
*>          VL is DOUBLE PRECISION array, dimension (LDVL,N)
*>          If JOBVL = 'V', the left eigenvectors u(j) are stored one
*>          after another in the columns of VL, in the same order
*>          as their eigenvalues.
*>          If JOBVL = 'N', VL is not referenced.
*>          If the j-th eigenvalue is real, then u(j) = VL(:,j),
*>          the j-th column of VL.
*>          If the j-th and (j+1)-st eigenvalues form a complex
*>          conjugate pair, then u(j) = VL(:,j) + i*VL(:,j+1) and
*>          u(j+1) = VL(:,j) - i*VL(:,j+1).
*> \endverbatim
*>
*> \param[in] LDVL
*> \verbatim
*>          LDVL is INTEGER
*>          The leading dimension of the array VL.  LDVL >= 1; if
*>          JOBVL = 'V', LDVL >= N.
*> \endverbatim
*>
*> \param[out] VR
*> \verbatim
*>          VR is DOUBLE PRECISION array, dimension (LDVR,N)
*>          If JOBVR = 'V', the right eigenvectors v(j) are stored one
*>          after another in the columns of VR, in the same order
*>          as their eigenvalues.
*>          If JOBVR = 'N', VR is not referenced.
*>          If the j-th eigenvalue is real, then v(j) = VR(:,j),
*>          the j-th column of VR.
*>          If the j-th and (j+1)-st eigenvalues form a complex
*>          conjugate pair, then v(j) = VR(:,j) + i*VR(:,j+1) and
*>          v(j+1) = VR(:,j) - i*VR(:,j+1).
*> \endverbatim
*>
*> \param[in] LDVR
*> \verbatim
*>          LDVR is INTEGER
*>          The leading dimension of the array VR.  LDVR >= 1, and if
*>          JOBVR = 'V', LDVR >= N.
*> \endverbatim
*>
*> \param[out] ILO
*> \verbatim
*>          ILO is INTEGER
*> \endverbatim
*>
*> \param[out] IHI
*> \verbatim
*>          IHI is INTEGER
*>          ILO and IHI are integer values determined when A was
*>          balanced.  The balanced A(i,j) = 0 if I > J and
*>          J = 1,...,ILO-1 or I = IHI+1,...,N.
*> \endverbatim
*>
*> \param[out] SCALE
*> \verbatim
*>          SCALE is DOUBLE PRECISION array, dimension (N)
*>          Details of the permutations and scaling factors applied
*>          when balancing A.  If P(j) is the index of the row and column
*>          interchanged with row and column j, and D(j) is the scaling
*>          factor applied to row and column j, then
*>          SCALE(J) = P(J),    for J = 1,...,ILO-1
*>                   = D(J),    for J = ILO,...,IHI
*>                   = P(J)     for J = IHI+1,...,N.
*>          The order in which the interchanges are made is N to IHI+1,
*>          then 1 to ILO-1.
*> \endverbatim
*>
*> \param[out] ABNRM
*> \verbatim
*>          ABNRM is DOUBLE PRECISION
*>          The one-norm of the balanced matrix (the maximum
*>          of the sum of absolute values of elements of any column).
*> \endverbatim
*>
*> \param[out] RCONDE
*> \verbatim
*>          RCONDE is DOUBLE PRECISION array, dimension (N)
*>          RCONDE(j) is the reciprocal condition number of the j-th
*>          eigenvalue.
*> \endverbatim
*>
*> \param[out] RCONDV
*> \verbatim
*>          RCONDV is DOUBLE PRECISION array, dimension (N)
*>          RCONDV(j) is the reciprocal condition number of the j-th
*>          right eigenvector.
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK))
*>          On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
*> \endverbatim
*>
*> \param[in] LWORK
*> \verbatim
*>          LWORK is INTEGER
*>          The dimension of the array WORK.   If SENSE = 'N' or 'E',
*>          LWORK >= max(1,2*N), and if JOBVL = 'V' or JOBVR = 'V',
*>          LWORK >= 3*N.  If SENSE = 'V' or 'B', LWORK >= N*(N+6).
*>          For good performance, LWORK must generally be larger.
*>
*>          If LWORK = -1, then a workspace query is assumed; the routine
*>          only calculates the optimal size of the WORK array, returns
*>          this value as the first entry of the WORK array, and no error
*>          message related to LWORK is issued by XERBLA.
*> \endverbatim
*>
*> \param[out] IWORK
*> \verbatim
*>          IWORK is INTEGER array, dimension (2*N-2)
*>          If SENSE = 'N' or 'E', not referenced.
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value.
*>          > 0:  if INFO = i, the QR algorithm failed to compute all the
*>                eigenvalues, and no eigenvectors or condition numbers
*>                have been computed; elements 1:ILO-1 and i+1:N of WR
*>                and WI contain eigenvalues which have converged.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date June 2016
*
*  @precisions fortran d -> s
*
*> \ingroup doubleGEeigen
*
*  =====================================================================
      SUBROUTINE DGEEVX( BALANC, JOBVL, JOBVR, SENSE, N, A, LDA, WR, WI,
     $                   VL, LDVL, VR, LDVR, ILO, IHI, SCALE, ABNRM,
     $                   RCONDE, RCONDV, WORK, LWORK, IWORK, INFO )
      implicit none
*
*  -- LAPACK driver routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     June 2016
*
*     .. Scalar Arguments ..
      CHARACTER          BALANC, JOBVL, JOBVR, SENSE
      INTEGER            IHI, ILO, INFO, LDA, LDVL, LDVR, LWORK, N
      DOUBLE PRECISION   ABNRM
*     ..
*     .. Array Arguments ..
      INTEGER            IWORK( * )
      DOUBLE PRECISION   A( LDA, * ), RCONDE( * ), RCONDV( * ),
     $                   SCALE( * ), VL( LDVL, * ), VR( LDVR, * ),
     $                   WI( * ), WORK( * ), WR( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ZERO, ONE
      PARAMETER          ( ZERO = 0.0D0, ONE = 1.0D0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            LQUERY, SCALEA, WANTVL, WANTVR, WNTSNB, WNTSNE,
     $                   WNTSNN, WNTSNV
      CHARACTER          JOB, SIDE
      INTEGER            HSWORK, I, ICOND, IERR, ITAU, IWRK, K,
     $                   LWORK_TREVC, MAXWRK, MINWRK, NOUT
      DOUBLE PRECISION   ANRM, BIGNUM, CS, CSCALE, EPS, R, SCL, SMLNUM,
     $                   SN
*     ..
*     .. Local Arrays ..
      LOGICAL            SELECT( 1 )
      DOUBLE PRECISION   DUM( 1 )
*     ..
*     .. External Subroutines ..
      EXTERNAL           DGEBAK, DGEBAL, DGEHRD, DHSEQR, DLABAD, DLACPY,
     $                   DLARTG, DLASCL, DORGHR, DROT, DSCAL, DTREVC3,
     $                   DTRSNA, XERBLA
*     ..
*     .. External Functions ..
      LOGICAL            LSAME
      INTEGER            IDAMAX, ILAENV
      DOUBLE PRECISION   DLAMCH, DLANGE, DLAPY2, DNRM2
      EXTERNAL           LSAME, IDAMAX, ILAENV, DLAMCH, DLANGE, DLAPY2,
     $                   DNRM2
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, SQRT
*     ..
*     .. Executable Statements ..
*
*     Test the input arguments
*
      INFO = 0
      LQUERY = ( LWORK.EQ.-1 )
      WANTVL = LSAME( JOBVL, 'V' )
      WANTVR = LSAME( JOBVR, 'V' )
      WNTSNN = LSAME( SENSE, 'N' )
      WNTSNE = LSAME( SENSE, 'E' )
      WNTSNV = LSAME( SENSE, 'V' )
      WNTSNB = LSAME( SENSE, 'B' )
      IF( .NOT.( LSAME( BALANC, 'N' ) .OR. LSAME( BALANC, 'S' )
     $      .OR. LSAME( BALANC, 'P' ) .OR. LSAME( BALANC, 'B' ) ) )
     $     THEN
         INFO = -1
      ELSE IF( ( .NOT.WANTVL ) .AND. ( .NOT.LSAME( JOBVL, 'N' ) ) ) THEN
         INFO = -2
      ELSE IF( ( .NOT.WANTVR ) .AND. ( .NOT.LSAME( JOBVR, 'N' ) ) ) THEN
         INFO = -3
      ELSE IF( .NOT.( WNTSNN .OR. WNTSNE .OR. WNTSNB .OR. WNTSNV ) .OR.
     $         ( ( WNTSNE .OR. WNTSNB ) .AND. .NOT.( WANTVL .AND.
     $         WANTVR ) ) ) THEN
         INFO = -4
      ELSE IF( N.LT.0 ) THEN
         INFO = -5
      ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
         INFO = -7
      ELSE IF( LDVL.LT.1 .OR. ( WANTVL .AND. LDVL.LT.N ) ) THEN
         INFO = -11
      ELSE IF( LDVR.LT.1 .OR. ( WANTVR .AND. LDVR.LT.N ) ) THEN
         INFO = -13
      END IF
*
*     Compute workspace
*      (Note: Comments in the code beginning "Workspace:" describe the
*       minimal amount of workspace needed at that point in the code,
*       as well as the preferred amount for good performance.
*       NB refers to the optimal block size for the immediately
*       following subroutine, as returned by ILAENV.
*       HSWORK refers to the workspace preferred by DHSEQR, as
*       calculated below. HSWORK is computed assuming ILO=1 and IHI=N,
*       the worst case.)
*
      IF( INFO.EQ.0 ) THEN
         IF( N.EQ.0 ) THEN
            MINWRK = 1
            MAXWRK = 1
         ELSE
            MAXWRK = N + N*ILAENV( 1, 'DGEHRD', ' ', N, 1, N, 0 )
*
            IF( WANTVL ) THEN
               CALL DTREVC3( 'L', 'B', SELECT, N, A, LDA,
     $                       VL, LDVL, VR, LDVR,
     $                       N, NOUT, WORK, -1, IERR )
               LWORK_TREVC = INT( WORK(1) )
               MAXWRK = MAX( MAXWRK, N + LWORK_TREVC )
               CALL DHSEQR( 'S', 'V', N, 1, N, A, LDA, WR, WI, VL, LDVL,
     $                WORK, -1, INFO )
            ELSE IF( WANTVR ) THEN
               CALL DTREVC3( 'R', 'B', SELECT, N, A, LDA,
     $                       VL, LDVL, VR, LDVR,
     $                       N, NOUT, WORK, -1, IERR )
               LWORK_TREVC = INT( WORK(1) )
               MAXWRK = MAX( MAXWRK, N + LWORK_TREVC )
               CALL DHSEQR( 'S', 'V', N, 1, N, A, LDA, WR, WI, VR, LDVR,
     $                WORK, -1, INFO )
            ELSE
               IF( WNTSNN ) THEN
                  CALL DHSEQR( 'E', 'N', N, 1, N, A, LDA, WR, WI, VR,
     $                LDVR, WORK, -1, INFO )
               ELSE
                  CALL DHSEQR( 'S', 'N', N, 1, N, A, LDA, WR, WI, VR,
     $                LDVR, WORK, -1, INFO )
               END IF
            END IF
            HSWORK = INT( WORK(1) )
*
            IF( ( .NOT.WANTVL ) .AND. ( .NOT.WANTVR ) ) THEN
               MINWRK = 2*N
               IF( .NOT.WNTSNN )
     $            MINWRK = MAX( MINWRK, N*N+6*N )
               MAXWRK = MAX( MAXWRK, HSWORK )
               IF( .NOT.WNTSNN )
     $            MAXWRK = MAX( MAXWRK, N*N + 6*N )
            ELSE
               MINWRK = 3*N
               IF( ( .NOT.WNTSNN ) .AND. ( .NOT.WNTSNE ) )
     $            MINWRK = MAX( MINWRK, N*N + 6*N )
               MAXWRK = MAX( MAXWRK, HSWORK )
               MAXWRK = MAX( MAXWRK, N + ( N - 1 )*ILAENV( 1, 'DORGHR',
     $                       ' ', N, 1, N, -1 ) )
               IF( ( .NOT.WNTSNN ) .AND. ( .NOT.WNTSNE ) )
     $            MAXWRK = MAX( MAXWRK, N*N + 6*N )
               MAXWRK = MAX( MAXWRK, 3*N )
            END IF
            MAXWRK = MAX( MAXWRK, MINWRK )
         END IF
         WORK( 1 ) = MAXWRK
*
         IF( LWORK.LT.MINWRK .AND. .NOT.LQUERY ) THEN
            INFO = -21
         END IF
      END IF
*
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGEEVX', -INFO )
         RETURN
      ELSE IF( LQUERY ) THEN
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( N.EQ.0 )
     $   RETURN
*
*     Get machine constants
*
      EPS = DLAMCH( 'P' )
      SMLNUM = DLAMCH( 'S' )
      BIGNUM = ONE / SMLNUM
      CALL DLABAD( SMLNUM, BIGNUM )
      SMLNUM = SQRT( SMLNUM ) / EPS
      BIGNUM = ONE / SMLNUM
*
*     Scale A if max element outside range [SMLNUM,BIGNUM]
*
      ICOND = 0
      ANRM = DLANGE( 'M', N, N, A, LDA, DUM )
      SCALEA = .FALSE.
      IF( ANRM.GT.ZERO .AND. ANRM.LT.SMLNUM ) THEN
         SCALEA = .TRUE.
         CSCALE = SMLNUM
      ELSE IF( ANRM.GT.BIGNUM ) THEN
         SCALEA = .TRUE.
         CSCALE = BIGNUM
      END IF
      IF( SCALEA )
     $   CALL DLASCL( 'G', 0, 0, ANRM, CSCALE, N, N, A, LDA, IERR )
*
*     Balance the matrix and compute ABNRM
*
      CALL DGEBAL( BALANC, N, A, LDA, ILO, IHI, SCALE, IERR )
      ABNRM = DLANGE( '1', N, N, A, LDA, DUM )
      IF( SCALEA ) THEN
         DUM( 1 ) = ABNRM
         CALL DLASCL( 'G', 0, 0, CSCALE, ANRM, 1, 1, DUM, 1, IERR )
         ABNRM = DUM( 1 )
      END IF
*
*     Reduce to upper Hessenberg form
*     (Workspace: need 2*N, prefer N+N*NB)
*
      ITAU = 1
      IWRK = ITAU + N
      CALL DGEHRD( N, ILO, IHI, A, LDA, WORK( ITAU ), WORK( IWRK ),
     $             LWORK-IWRK+1, IERR )
*
      IF( WANTVL ) THEN
*
*        Want left eigenvectors
*        Copy Householder vectors to VL
*
         SIDE = 'L'
         CALL DLACPY( 'L', N, N, A, LDA, VL, LDVL )
*
*        Generate orthogonal matrix in VL
*        (Workspace: need 2*N-1, prefer N+(N-1)*NB)
*
         CALL DORGHR( N, ILO, IHI, VL, LDVL, WORK( ITAU ), WORK( IWRK ),
     $                LWORK-IWRK+1, IERR )
*
*        Perform QR iteration, accumulating Schur vectors in VL
*        (Workspace: need 1, prefer HSWORK (see comments) )
*
         IWRK = ITAU
         CALL DHSEQR( 'S', 'V', N, ILO, IHI, A, LDA, WR, WI, VL, LDVL,
     $                WORK( IWRK ), LWORK-IWRK+1, INFO )
*
         IF( WANTVR ) THEN
*
*           Want left and right eigenvectors
*           Copy Schur vectors to VR
*
            SIDE = 'B'
            CALL DLACPY( 'F', N, N, VL, LDVL, VR, LDVR )
         END IF
*
      ELSE IF( WANTVR ) THEN
*
*        Want right eigenvectors
*        Copy Householder vectors to VR
*
         SIDE = 'R'
         CALL DLACPY( 'L', N, N, A, LDA, VR, LDVR )
*
*        Generate orthogonal matrix in VR
*        (Workspace: need 2*N-1, prefer N+(N-1)*NB)
*
         CALL DORGHR( N, ILO, IHI, VR, LDVR, WORK( ITAU ), WORK( IWRK ),
     $                LWORK-IWRK+1, IERR )
*
*        Perform QR iteration, accumulating Schur vectors in VR
*        (Workspace: need 1, prefer HSWORK (see comments) )
*
         IWRK = ITAU
         CALL DHSEQR( 'S', 'V', N, ILO, IHI, A, LDA, WR, WI, VR, LDVR,
     $                WORK( IWRK ), LWORK-IWRK+1, INFO )
*
      ELSE
*
*        Compute eigenvalues only
*        If condition numbers desired, compute Schur form
*
         IF( WNTSNN ) THEN
            JOB = 'E'
         ELSE
            JOB = 'S'
         END IF
*
*        (Workspace: need 1, prefer HSWORK (see comments) )
*
         IWRK = ITAU
         CALL DHSEQR( JOB, 'N', N, ILO, IHI, A, LDA, WR, WI, VR, LDVR,
     $                WORK( IWRK ), LWORK-IWRK+1, INFO )
      END IF
*
*     If INFO .NE. 0 from DHSEQR, then quit
*
      IF( INFO.NE.0 )
     $   GO TO 50
*
      IF( WANTVL .OR. WANTVR ) THEN
*
*        Compute left and/or right eigenvectors
*        (Workspace: need 3*N, prefer N + 2*N*NB)
*
         CALL DTREVC3( SIDE, 'B', SELECT, N, A, LDA, VL, LDVL, VR, LDVR,
     $                 N, NOUT, WORK( IWRK ), LWORK-IWRK+1, IERR )
      END IF
*
*     Compute condition numbers if desired
*     (Workspace: need N*N+6*N unless SENSE = 'E')
*
      IF( .NOT.WNTSNN ) THEN
         CALL DTRSNA( SENSE, 'A', SELECT, N, A, LDA, VL, LDVL, VR, LDVR,
     $                RCONDE, RCONDV, N, NOUT, WORK( IWRK ), N, IWORK,
     $                ICOND )
      END IF
*
      IF( WANTVL ) THEN
*
*        Undo balancing of left eigenvectors
*
         CALL DGEBAK( BALANC, 'L', N, ILO, IHI, SCALE, N, VL, LDVL,
     $                IERR )
*
*        Normalize left eigenvectors and make largest component real
*
         DO 20 I = 1, N
            IF( WI( I ).EQ.ZERO ) THEN
               SCL = ONE / DNRM2( N, VL( 1, I ), 1 )
               CALL DSCAL( N, SCL, VL( 1, I ), 1 )
            ELSE IF( WI( I ).GT.ZERO ) THEN
               SCL = ONE / DLAPY2( DNRM2( N, VL( 1, I ), 1 ),
     $               DNRM2( N, VL( 1, I+1 ), 1 ) )
               CALL DSCAL( N, SCL, VL( 1, I ), 1 )
               CALL DSCAL( N, SCL, VL( 1, I+1 ), 1 )
               DO 10 K = 1, N
                  WORK( K ) = VL( K, I )**2 + VL( K, I+1 )**2
   10          CONTINUE
               K = IDAMAX( N, WORK, 1 )
               CALL DLARTG( VL( K, I ), VL( K, I+1 ), CS, SN, R )
               CALL DROT( N, VL( 1, I ), 1, VL( 1, I+1 ), 1, CS, SN )
               VL( K, I+1 ) = ZERO
            END IF
   20    CONTINUE
      END IF
*
      IF( WANTVR ) THEN
*
*        Undo balancing of right eigenvectors
*
         CALL DGEBAK( BALANC, 'R', N, ILO, IHI, SCALE, N, VR, LDVR,
     $                IERR )
*
*        Normalize right eigenvectors and make largest component real
*
         DO 40 I = 1, N
            IF( WI( I ).EQ.ZERO ) THEN
               SCL = ONE / DNRM2( N, VR( 1, I ), 1 )
               CALL DSCAL( N, SCL, VR( 1, I ), 1 )
            ELSE IF( WI( I ).GT.ZERO ) THEN
               SCL = ONE / DLAPY2( DNRM2( N, VR( 1, I ), 1 ),
     $               DNRM2( N, VR( 1, I+1 ), 1 ) )
               CALL DSCAL( N, SCL, VR( 1, I ), 1 )
               CALL DSCAL( N, SCL, VR( 1, I+1 ), 1 )
               DO 30 K = 1, N
                  WORK( K ) = VR( K, I )**2 + VR( K, I+1 )**2
   30          CONTINUE
               K = IDAMAX( N, WORK, 1 )
               CALL DLARTG( VR( K, I ), VR( K, I+1 ), CS, SN, R )
               CALL DROT( N, VR( 1, I ), 1, VR( 1, I+1 ), 1, CS, SN )
               VR( K, I+1 ) = ZERO
            END IF
   40    CONTINUE
      END IF
*
*     Undo scaling if necessary
*
   50 CONTINUE
      IF( SCALEA ) THEN
         CALL DLASCL( 'G', 0, 0, CSCALE, ANRM, N-INFO, 1, WR( INFO+1 ),
     $                MAX( N-INFO, 1 ), IERR )
         CALL DLASCL( 'G', 0, 0, CSCALE, ANRM, N-INFO, 1, WI( INFO+1 ),
     $                MAX( N-INFO, 1 ), IERR )
         IF( INFO.EQ.0 ) THEN
            IF( ( WNTSNV .OR. WNTSNB ) .AND. ICOND.EQ.0 )
     $         CALL DLASCL( 'G', 0, 0, CSCALE, ANRM, N, 1, RCONDV, N,
     $                      IERR )
         ELSE
            CALL DLASCL( 'G', 0, 0, CSCALE, ANRM, ILO-1, 1, WR, N,
     $                   IERR )
            CALL DLASCL( 'G', 0, 0, CSCALE, ANRM, ILO-1, 1, WI, N,
     $                   IERR )
         END IF
      END IF
*
      WORK( 1 ) = MAXWRK
      RETURN
*
*     End of DGEEVX
*
      END
*> \brief <b> DGEEVX computes the eigenvalues and, optionally, the left and/or right eigenvectors for GE matrices</b>
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGEGS + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgegs.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgegs.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgegs.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGEGS( JOBVSL, JOBVSR, N, A, LDA, B, LDB, ALPHAR,
*                         ALPHAI, BETA, VSL, LDVSL, VSR, LDVSR, WORK,
*                         LWORK, INFO )
*
*       .. Scalar Arguments ..
*       CHARACTER          JOBVSL, JOBVSR
*       INTEGER            INFO, LDA, LDB, LDVSL, LDVSR, LWORK, N
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   A( LDA, * ), ALPHAI( * ), ALPHAR( * ),
*      $                   B( LDB, * ), BETA( * ), VSL( LDVSL, * ),
*      $                   VSR( LDVSR, * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> This routine is deprecated and has been replaced by routine DGGES.
*>
*> DGEGS computes the eigenvalues, real Schur form, and, optionally,
*> left and or/right Schur vectors of a real matrix pair (A,B).
*> Given two square matrices A and B, the generalized real Schur
*> factorization has the form
*>
*>   A = Q*S*Z**T,  B = Q*T*Z**T
*>
*> where Q and Z are orthogonal matrices, T is upper triangular, and S
*> is an upper quasi-triangular matrix with 1-by-1 and 2-by-2 diagonal
*> blocks, the 2-by-2 blocks corresponding to complex conjugate pairs
*> of eigenvalues of (A,B).  The columns of Q are the left Schur vectors
*> and the columns of Z are the right Schur vectors.
*>
*> If only the eigenvalues of (A,B) are needed, the driver routine
*> DGEGV should be used instead.  See DGEGV for a description of the
*> eigenvalues of the generalized nonsymmetric eigenvalue problem
*> (GNEP).
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] JOBVSL
*> \verbatim
*>          JOBVSL is CHARACTER*1
*>          = 'N':  do not compute the left Schur vectors;
*>          = 'V':  compute the left Schur vectors (returned in VSL).
*> \endverbatim
*>
*> \param[in] JOBVSR
*> \verbatim
*>          JOBVSR is CHARACTER*1
*>          = 'N':  do not compute the right Schur vectors;
*>          = 'V':  compute the right Schur vectors (returned in VSR).
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The order of the matrices A, B, VSL, and VSR.  N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA, N)
*>          On entry, the matrix A.
*>          On exit, the upper quasi-triangular matrix S from the
*>          generalized real Schur factorization.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of A.  LDA >= max(1,N).
*> \endverbatim
*>
*> \param[in,out] B
*> \verbatim
*>          B is DOUBLE PRECISION array, dimension (LDB, N)
*>          On entry, the matrix B.
*>          On exit, the upper triangular matrix T from the generalized
*>          real Schur factorization.
*> \endverbatim
*>
*> \param[in] LDB
*> \verbatim
*>          LDB is INTEGER
*>          The leading dimension of B.  LDB >= max(1,N).
*> \endverbatim
*>
*> \param[out] ALPHAR
*> \verbatim
*>          ALPHAR is DOUBLE PRECISION array, dimension (N)
*>          The real parts of each scalar alpha defining an eigenvalue
*>          of GNEP.
*> \endverbatim
*>
*> \param[out] ALPHAI
*> \verbatim
*>          ALPHAI is DOUBLE PRECISION array, dimension (N)
*>          The imaginary parts of each scalar alpha defining an
*>          eigenvalue of GNEP.  If ALPHAI(j) is zero, then the j-th
*>          eigenvalue is real; if positive, then the j-th and (j+1)-st
*>          eigenvalues are a complex conjugate pair, with
*>          ALPHAI(j+1) = -ALPHAI(j).
*> \endverbatim
*>
*> \param[out] BETA
*> \verbatim
*>          BETA is DOUBLE PRECISION array, dimension (N)
*>          The scalars beta that define the eigenvalues of GNEP.
*>          Together, the quantities alpha = (ALPHAR(j),ALPHAI(j)) and
*>          beta = BETA(j) represent the j-th eigenvalue of the matrix
*>          pair (A,B), in one of the forms lambda = alpha/beta or
*>          mu = beta/alpha.  Since either lambda or mu may overflow,
*>          they should not, in general, be computed.
*> \endverbatim
*>
*> \param[out] VSL
*> \verbatim
*>          VSL is DOUBLE PRECISION array, dimension (LDVSL,N)
*>          If JOBVSL = 'V', the matrix of left Schur vectors Q.
*>          Not referenced if JOBVSL = 'N'.
*> \endverbatim
*>
*> \param[in] LDVSL
*> \verbatim
*>          LDVSL is INTEGER
*>          The leading dimension of the matrix VSL. LDVSL >=1, and
*>          if JOBVSL = 'V', LDVSL >= N.
*> \endverbatim
*>
*> \param[out] VSR
*> \verbatim
*>          VSR is DOUBLE PRECISION array, dimension (LDVSR,N)
*>          If JOBVSR = 'V', the matrix of right Schur vectors Z.
*>          Not referenced if JOBVSR = 'N'.
*> \endverbatim
*>
*> \param[in] LDVSR
*> \verbatim
*>          LDVSR is INTEGER
*>          The leading dimension of the matrix VSR. LDVSR >= 1, and
*>          if JOBVSR = 'V', LDVSR >= N.
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK))
*>          On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
*> \endverbatim
*>
*> \param[in] LWORK
*> \verbatim
*>          LWORK is INTEGER
*>          The dimension of the array WORK.  LWORK >= max(1,4*N).
*>          For good performance, LWORK must generally be larger.
*>          To compute the optimal value of LWORK, call ILAENV to get
*>          blocksizes (for DGEQRF, DORMQR, and DORGQR.)  Then compute:
*>          NB  -- MAX of the blocksizes for DGEQRF, DORMQR, and DORGQR
*>          The optimal LWORK is  2*N + N*(NB+1).
*>
*>          If LWORK = -1, then a workspace query is assumed; the routine
*>          only calculates the optimal size of the WORK array, returns
*>          this value as the first entry of the WORK array, and no error
*>          message related to LWORK is issued by XERBLA.
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value.
*>          = 1,...,N:
*>                The QZ iteration failed.  (A,B) are not in Schur
*>                form, but ALPHAR(j), ALPHAI(j), and BETA(j) should
*>                be correct for j=INFO+1,...,N.
*>          > N:  errors that usually indicate LAPACK problems:
*>                =N+1: error return from DGGBAL
*>                =N+2: error return from DGEQRF
*>                =N+3: error return from DORMQR
*>                =N+4: error return from DORGQR
*>                =N+5: error return from DGGHRD
*>                =N+6: error return from DHGEQZ (other than failed
*>                                                iteration)
*>                =N+7: error return from DGGBAK (computing VSL)
*>                =N+8: error return from DGGBAK (computing VSR)
*>                =N+9: error return from DLASCL (various places)
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEeigen
*
*  =====================================================================
      SUBROUTINE DGEGS( JOBVSL, JOBVSR, N, A, LDA, B, LDB, ALPHAR,
     $                  ALPHAI, BETA, VSL, LDVSL, VSR, LDVSR, WORK,
     $                  LWORK, INFO )
*
*  -- LAPACK driver routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      CHARACTER          JOBVSL, JOBVSR
      INTEGER            INFO, LDA, LDB, LDVSL, LDVSR, LWORK, N
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   A( LDA, * ), ALPHAI( * ), ALPHAR( * ),
     $                   B( LDB, * ), BETA( * ), VSL( LDVSL, * ),
     $                   VSR( LDVSR, * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ZERO, ONE
      PARAMETER          ( ZERO = 0.0D0, ONE = 1.0D0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            ILASCL, ILBSCL, ILVSL, ILVSR, LQUERY
      INTEGER            ICOLS, IHI, IINFO, IJOBVL, IJOBVR, ILEFT, ILO,
     $                   IRIGHT, IROWS, ITAU, IWORK, LOPT, LWKMIN,
     $                   LWKOPT, NB, NB1, NB2, NB3
      DOUBLE PRECISION   ANRM, ANRMTO, BIGNUM, BNRM, BNRMTO, EPS,
     $                   SAFMIN, SMLNUM
*     ..
*     .. External Subroutines ..
      EXTERNAL           DGEQRF, DGGBAK, DGGBAL, DGGHRD, DHGEQZ, DLACPY,
     $                   DLASCL, DLASET, DORGQR, DORMQR, XERBLA
*     ..
*     .. External Functions ..
      LOGICAL            LSAME
      INTEGER            ILAENV
      DOUBLE PRECISION   DLAMCH, DLANGE
      EXTERNAL           LSAME, ILAENV, DLAMCH, DLANGE
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          INT, MAX
*     ..
*     .. Executable Statements ..
*
*     Decode the input arguments
*
      IF( LSAME( JOBVSL, 'N' ) ) THEN
         IJOBVL = 1
         ILVSL = .FALSE.
      ELSE IF( LSAME( JOBVSL, 'V' ) ) THEN
         IJOBVL = 2
         ILVSL = .TRUE.
      ELSE
         IJOBVL = -1
         ILVSL = .FALSE.
      END IF
*
      IF( LSAME( JOBVSR, 'N' ) ) THEN
         IJOBVR = 1
         ILVSR = .FALSE.
      ELSE IF( LSAME( JOBVSR, 'V' ) ) THEN
         IJOBVR = 2
         ILVSR = .TRUE.
      ELSE
         IJOBVR = -1
         ILVSR = .FALSE.
      END IF
*
*     Test the input arguments
*
      LWKMIN = MAX( 4*N, 1 )
      LWKOPT = LWKMIN
      WORK( 1 ) = LWKOPT
      LQUERY = ( LWORK.EQ.-1 )
      INFO = 0
      IF( IJOBVL.LE.0 ) THEN
         INFO = -1
      ELSE IF( IJOBVR.LE.0 ) THEN
         INFO = -2
      ELSE IF( N.LT.0 ) THEN
         INFO = -3
      ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
         INFO = -5
      ELSE IF( LDB.LT.MAX( 1, N ) ) THEN
         INFO = -7
      ELSE IF( LDVSL.LT.1 .OR. ( ILVSL .AND. LDVSL.LT.N ) ) THEN
         INFO = -12
      ELSE IF( LDVSR.LT.1 .OR. ( ILVSR .AND. LDVSR.LT.N ) ) THEN
         INFO = -14
      ELSE IF( LWORK.LT.LWKMIN .AND. .NOT.LQUERY ) THEN
         INFO = -16
      END IF
*
      IF( INFO.EQ.0 ) THEN
         NB1 = ILAENV( 1, 'DGEQRF', ' ', N, N, -1, -1 )
         NB2 = ILAENV( 1, 'DORMQR', ' ', N, N, N, -1 )
         NB3 = ILAENV( 1, 'DORGQR', ' ', N, N, N, -1 )
         NB = MAX( NB1, NB2, NB3 )
         LOPT = 2*N + N*( NB+1 )
         WORK( 1 ) = LOPT
      END IF
*
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGEGS ', -INFO )
         RETURN
      ELSE IF( LQUERY ) THEN
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( N.EQ.0 )
     $   RETURN
*
*     Get machine constants
*
      EPS = DLAMCH( 'E' )*DLAMCH( 'B' )
      SAFMIN = DLAMCH( 'S' )
      SMLNUM = N*SAFMIN / EPS
      BIGNUM = ONE / SMLNUM
*
*     Scale A if max element outside range [SMLNUM,BIGNUM]
*
      ANRM = DLANGE( 'M', N, N, A, LDA, WORK )
      ILASCL = .FALSE.
      IF( ANRM.GT.ZERO .AND. ANRM.LT.SMLNUM ) THEN
         ANRMTO = SMLNUM
         ILASCL = .TRUE.
      ELSE IF( ANRM.GT.BIGNUM ) THEN
         ANRMTO = BIGNUM
         ILASCL = .TRUE.
      END IF
*
      IF( ILASCL ) THEN
         CALL DLASCL( 'G', -1, -1, ANRM, ANRMTO, N, N, A, LDA, IINFO )
         IF( IINFO.NE.0 ) THEN
            INFO = N + 9
            RETURN
         END IF
      END IF
*
*     Scale B if max element outside range [SMLNUM,BIGNUM]
*
      BNRM = DLANGE( 'M', N, N, B, LDB, WORK )
      ILBSCL = .FALSE.
      IF( BNRM.GT.ZERO .AND. BNRM.LT.SMLNUM ) THEN
         BNRMTO = SMLNUM
         ILBSCL = .TRUE.
      ELSE IF( BNRM.GT.BIGNUM ) THEN
         BNRMTO = BIGNUM
         ILBSCL = .TRUE.
      END IF
*
      IF( ILBSCL ) THEN
         CALL DLASCL( 'G', -1, -1, BNRM, BNRMTO, N, N, B, LDB, IINFO )
         IF( IINFO.NE.0 ) THEN
            INFO = N + 9
            RETURN
         END IF
      END IF
*
*     Permute the matrix to make it more nearly triangular
*     Workspace layout:  (2*N words -- "work..." not actually used)
*        left_permutation, right_permutation, work...
*
      ILEFT = 1
      IRIGHT = N + 1
      IWORK = IRIGHT + N
      CALL DGGBAL( 'P', N, A, LDA, B, LDB, ILO, IHI, WORK( ILEFT ),
     $             WORK( IRIGHT ), WORK( IWORK ), IINFO )
      IF( IINFO.NE.0 ) THEN
         INFO = N + 1
         GO TO 10
      END IF
*
*     Reduce B to triangular form, and initialize VSL and/or VSR
*     Workspace layout:  ("work..." must have at least N words)
*        left_permutation, right_permutation, tau, work...
*
      IROWS = IHI + 1 - ILO
      ICOLS = N + 1 - ILO
      ITAU = IWORK
      IWORK = ITAU + IROWS
      CALL DGEQRF( IROWS, ICOLS, B( ILO, ILO ), LDB, WORK( ITAU ),
     $             WORK( IWORK ), LWORK+1-IWORK, IINFO )
      IF( IINFO.GE.0 )
     $   LWKOPT = MAX( LWKOPT, INT( WORK( IWORK ) )+IWORK-1 )
      IF( IINFO.NE.0 ) THEN
         INFO = N + 2
         GO TO 10
      END IF
*
      CALL DORMQR( 'L', 'T', IROWS, ICOLS, IROWS, B( ILO, ILO ), LDB,
     $             WORK( ITAU ), A( ILO, ILO ), LDA, WORK( IWORK ),
     $             LWORK+1-IWORK, IINFO )
      IF( IINFO.GE.0 )
     $   LWKOPT = MAX( LWKOPT, INT( WORK( IWORK ) )+IWORK-1 )
      IF( IINFO.NE.0 ) THEN
         INFO = N + 3
         GO TO 10
      END IF
*
      IF( ILVSL ) THEN
         CALL DLASET( 'Full', N, N, ZERO, ONE, VSL, LDVSL )
         CALL DLACPY( 'L', IROWS-1, IROWS-1, B( ILO+1, ILO ), LDB,
     $                VSL( ILO+1, ILO ), LDVSL )
         CALL DORGQR( IROWS, IROWS, IROWS, VSL( ILO, ILO ), LDVSL,
     $                WORK( ITAU ), WORK( IWORK ), LWORK+1-IWORK,
     $                IINFO )
         IF( IINFO.GE.0 )
     $      LWKOPT = MAX( LWKOPT, INT( WORK( IWORK ) )+IWORK-1 )
         IF( IINFO.NE.0 ) THEN
            INFO = N + 4
            GO TO 10
         END IF
      END IF
*
      IF( ILVSR )
     $   CALL DLASET( 'Full', N, N, ZERO, ONE, VSR, LDVSR )
*
*     Reduce to generalized Hessenberg form
*
      CALL DGGHRD( JOBVSL, JOBVSR, N, ILO, IHI, A, LDA, B, LDB, VSL,
     $             LDVSL, VSR, LDVSR, IINFO )
      IF( IINFO.NE.0 ) THEN
         INFO = N + 5
         GO TO 10
      END IF
*
*     Perform QZ algorithm, computing Schur vectors if desired
*     Workspace layout:  ("work..." must have at least 1 word)
*        left_permutation, right_permutation, work...
*
      IWORK = ITAU
      CALL DHGEQZ( 'S', JOBVSL, JOBVSR, N, ILO, IHI, A, LDA, B, LDB,
     $             ALPHAR, ALPHAI, BETA, VSL, LDVSL, VSR, LDVSR,
     $             WORK( IWORK ), LWORK+1-IWORK, IINFO )
      IF( IINFO.GE.0 )
     $   LWKOPT = MAX( LWKOPT, INT( WORK( IWORK ) )+IWORK-1 )
      IF( IINFO.NE.0 ) THEN
         IF( IINFO.GT.0 .AND. IINFO.LE.N ) THEN
            INFO = IINFO
         ELSE IF( IINFO.GT.N .AND. IINFO.LE.2*N ) THEN
            INFO = IINFO - N
         ELSE
            INFO = N + 6
         END IF
         GO TO 10
      END IF
*
*     Apply permutation to VSL and VSR
*
      IF( ILVSL ) THEN
         CALL DGGBAK( 'P', 'L', N, ILO, IHI, WORK( ILEFT ),
     $                WORK( IRIGHT ), N, VSL, LDVSL, IINFO )
         IF( IINFO.NE.0 ) THEN
            INFO = N + 7
            GO TO 10
         END IF
      END IF
      IF( ILVSR ) THEN
         CALL DGGBAK( 'P', 'R', N, ILO, IHI, WORK( ILEFT ),
     $                WORK( IRIGHT ), N, VSR, LDVSR, IINFO )
         IF( IINFO.NE.0 ) THEN
            INFO = N + 8
            GO TO 10
         END IF
      END IF
*
*     Undo scaling
*
      IF( ILASCL ) THEN
         CALL DLASCL( 'H', -1, -1, ANRMTO, ANRM, N, N, A, LDA, IINFO )
         IF( IINFO.NE.0 ) THEN
            INFO = N + 9
            RETURN
         END IF
         CALL DLASCL( 'G', -1, -1, ANRMTO, ANRM, N, 1, ALPHAR, N,
     $                IINFO )
         IF( IINFO.NE.0 ) THEN
            INFO = N + 9
            RETURN
         END IF
         CALL DLASCL( 'G', -1, -1, ANRMTO, ANRM, N, 1, ALPHAI, N,
     $                IINFO )
         IF( IINFO.NE.0 ) THEN
            INFO = N + 9
            RETURN
         END IF
      END IF
*
      IF( ILBSCL ) THEN
         CALL DLASCL( 'U', -1, -1, BNRMTO, BNRM, N, N, B, LDB, IINFO )
         IF( IINFO.NE.0 ) THEN
            INFO = N + 9
            RETURN
         END IF
         CALL DLASCL( 'G', -1, -1, BNRMTO, BNRM, N, 1, BETA, N, IINFO )
         IF( IINFO.NE.0 ) THEN
            INFO = N + 9
            RETURN
         END IF
      END IF
*
   10 CONTINUE
      WORK( 1 ) = LWKOPT
*
      RETURN
*
*     End of DGEGS
*
      END
*> \brief <b> DGEEVX computes the eigenvalues and, optionally, the left and/or right eigenvectors for GE matrices</b>
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGEGV + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgegv.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgegv.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgegv.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGEGV( JOBVL, JOBVR, N, A, LDA, B, LDB, ALPHAR, ALPHAI,
*                         BETA, VL, LDVL, VR, LDVR, WORK, LWORK, INFO )
*
*       .. Scalar Arguments ..
*       CHARACTER          JOBVL, JOBVR
*       INTEGER            INFO, LDA, LDB, LDVL, LDVR, LWORK, N
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   A( LDA, * ), ALPHAI( * ), ALPHAR( * ),
*      $                   B( LDB, * ), BETA( * ), VL( LDVL, * ),
*      $                   VR( LDVR, * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> This routine is deprecated and has been replaced by routine DGGEV.
*>
*> DGEGV computes the eigenvalues and, optionally, the left and/or right
*> eigenvectors of a real matrix pair (A,B).
*> Given two square matrices A and B,
*> the generalized nonsymmetric eigenvalue problem (GNEP) is to find the
*> eigenvalues lambda and corresponding (non-zero) eigenvectors x such
*> that
*>
*>    A*x = lambda*B*x.
*>
*> An alternate form is to find the eigenvalues mu and corresponding
*> eigenvectors y such that
*>
*>    mu*A*y = B*y.
*>
*> These two forms are equivalent with mu = 1/lambda and x = y if
*> neither lambda nor mu is zero.  In order to deal with the case that
*> lambda or mu is zero or small, two values alpha and beta are returned
*> for each eigenvalue, such that lambda = alpha/beta and
*> mu = beta/alpha.
*>
*> The vectors x and y in the above equations are right eigenvectors of
*> the matrix pair (A,B).  Vectors u and v satisfying
*>
*>    u**H*A = lambda*u**H*B  or  mu*v**H*A = v**H*B
*>
*> are left eigenvectors of (A,B).
*>
*> Note: this routine performs "full balancing" on A and B
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] JOBVL
*> \verbatim
*>          JOBVL is CHARACTER*1
*>          = 'N':  do not compute the left generalized eigenvectors;
*>          = 'V':  compute the left generalized eigenvectors (returned
*>                  in VL).
*> \endverbatim
*>
*> \param[in] JOBVR
*> \verbatim
*>          JOBVR is CHARACTER*1
*>          = 'N':  do not compute the right generalized eigenvectors;
*>          = 'V':  compute the right generalized eigenvectors (returned
*>                  in VR).
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The order of the matrices A, B, VL, and VR.  N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA, N)
*>          On entry, the matrix A.
*>          If JOBVL = 'V' or JOBVR = 'V', then on exit A
*>          contains the real Schur form of A from the generalized Schur
*>          factorization of the pair (A,B) after balancing.
*>          If no eigenvectors were computed, then only the diagonal
*>          blocks from the Schur form will be correct.  See DGGHRD and
*>          DHGEQZ for details.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of A.  LDA >= max(1,N).
*> \endverbatim
*>
*> \param[in,out] B
*> \verbatim
*>          B is DOUBLE PRECISION array, dimension (LDB, N)
*>          On entry, the matrix B.
*>          If JOBVL = 'V' or JOBVR = 'V', then on exit B contains the
*>          upper triangular matrix obtained from B in the generalized
*>          Schur factorization of the pair (A,B) after balancing.
*>          If no eigenvectors were computed, then only those elements of
*>          B corresponding to the diagonal blocks from the Schur form of
*>          A will be correct.  See DGGHRD and DHGEQZ for details.
*> \endverbatim
*>
*> \param[in] LDB
*> \verbatim
*>          LDB is INTEGER
*>          The leading dimension of B.  LDB >= max(1,N).
*> \endverbatim
*>
*> \param[out] ALPHAR
*> \verbatim
*>          ALPHAR is DOUBLE PRECISION array, dimension (N)
*>          The real parts of each scalar alpha defining an eigenvalue of
*>          GNEP.
*> \endverbatim
*>
*> \param[out] ALPHAI
*> \verbatim
*>          ALPHAI is DOUBLE PRECISION array, dimension (N)
*>          The imaginary parts of each scalar alpha defining an
*>          eigenvalue of GNEP.  If ALPHAI(j) is zero, then the j-th
*>          eigenvalue is real; if positive, then the j-th and
*>          (j+1)-st eigenvalues are a complex conjugate pair, with
*>          ALPHAI(j+1) = -ALPHAI(j).
*> \endverbatim
*>
*> \param[out] BETA
*> \verbatim
*>          BETA is DOUBLE PRECISION array, dimension (N)
*>          The scalars beta that define the eigenvalues of GNEP.
*>
*>          Together, the quantities alpha = (ALPHAR(j),ALPHAI(j)) and
*>          beta = BETA(j) represent the j-th eigenvalue of the matrix
*>          pair (A,B), in one of the forms lambda = alpha/beta or
*>          mu = beta/alpha.  Since either lambda or mu may overflow,
*>          they should not, in general, be computed.
*> \endverbatim
*>
*> \param[out] VL
*> \verbatim
*>          VL is DOUBLE PRECISION array, dimension (LDVL,N)
*>          If JOBVL = 'V', the left eigenvectors u(j) are stored
*>          in the columns of VL, in the same order as their eigenvalues.
*>          If the j-th eigenvalue is real, then u(j) = VL(:,j).
*>          If the j-th and (j+1)-st eigenvalues form a complex conjugate
*>          pair, then
*>             u(j) = VL(:,j) + i*VL(:,j+1)
*>          and
*>            u(j+1) = VL(:,j) - i*VL(:,j+1).
*>
*>          Each eigenvector is scaled so that its largest component has
*>          abs(real part) + abs(imag. part) = 1, except for eigenvectors
*>          corresponding to an eigenvalue with alpha = beta = 0, which
*>          are set to zero.
*>          Not referenced if JOBVL = 'N'.
*> \endverbatim
*>
*> \param[in] LDVL
*> \verbatim
*>          LDVL is INTEGER
*>          The leading dimension of the matrix VL. LDVL >= 1, and
*>          if JOBVL = 'V', LDVL >= N.
*> \endverbatim
*>
*> \param[out] VR
*> \verbatim
*>          VR is DOUBLE PRECISION array, dimension (LDVR,N)
*>          If JOBVR = 'V', the right eigenvectors x(j) are stored
*>          in the columns of VR, in the same order as their eigenvalues.
*>          If the j-th eigenvalue is real, then x(j) = VR(:,j).
*>          If the j-th and (j+1)-st eigenvalues form a complex conjugate
*>          pair, then
*>            x(j) = VR(:,j) + i*VR(:,j+1)
*>          and
*>            x(j+1) = VR(:,j) - i*VR(:,j+1).
*>
*>          Each eigenvector is scaled so that its largest component has
*>          abs(real part) + abs(imag. part) = 1, except for eigenvalues
*>          corresponding to an eigenvalue with alpha = beta = 0, which
*>          are set to zero.
*>          Not referenced if JOBVR = 'N'.
*> \endverbatim
*>
*> \param[in] LDVR
*> \verbatim
*>          LDVR is INTEGER
*>          The leading dimension of the matrix VR. LDVR >= 1, and
*>          if JOBVR = 'V', LDVR >= N.
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK))
*>          On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
*> \endverbatim
*>
*> \param[in] LWORK
*> \verbatim
*>          LWORK is INTEGER
*>          The dimension of the array WORK.  LWORK >= max(1,8*N).
*>          For good performance, LWORK must generally be larger.
*>          To compute the optimal value of LWORK, call ILAENV to get
*>          blocksizes (for DGEQRF, DORMQR, and DORGQR.)  Then compute:
*>          NB  -- MAX of the blocksizes for DGEQRF, DORMQR, and DORGQR;
*>          The optimal LWORK is:
*>              2*N + MAX( 6*N, N*(NB+1) ).
*>
*>          If LWORK = -1, then a workspace query is assumed; the routine
*>          only calculates the optimal size of the WORK array, returns
*>          this value as the first entry of the WORK array, and no error
*>          message related to LWORK is issued by XERBLA.
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value.
*>          = 1,...,N:
*>                The QZ iteration failed.  No eigenvectors have been
*>                calculated, but ALPHAR(j), ALPHAI(j), and BETA(j)
*>                should be correct for j=INFO+1,...,N.
*>          > N:  errors that usually indicate LAPACK problems:
*>                =N+1: error return from DGGBAL
*>                =N+2: error return from DGEQRF
*>                =N+3: error return from DORMQR
*>                =N+4: error return from DORGQR
*>                =N+5: error return from DGGHRD
*>                =N+6: error return from DHGEQZ (other than failed
*>                                                iteration)
*>                =N+7: error return from DTGEVC
*>                =N+8: error return from DGGBAK (computing VL)
*>                =N+9: error return from DGGBAK (computing VR)
*>                =N+10: error return from DLASCL (various calls)
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEeigen
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>  Balancing
*>  ---------
*>
*>  This driver calls DGGBAL to both permute and scale rows and columns
*>  of A and B.  The permutations PL and PR are chosen so that PL*A*PR
*>  and PL*B*R will be upper triangular except for the diagonal blocks
*>  A(i:j,i:j) and B(i:j,i:j), with i and j as close together as
*>  possible.  The diagonal scaling matrices DL and DR are chosen so
*>  that the pair  DL*PL*A*PR*DR, DL*PL*B*PR*DR have elements close to
*>  one (except for the elements that start out zero.)
*>
*>  After the eigenvalues and eigenvectors of the balanced matrices
*>  have been computed, DGGBAK transforms the eigenvectors back to what
*>  they would have been (in perfect arithmetic) if they had not been
*>  balanced.
*>
*>  Contents of A and B on Exit
*>  -------- -- - --- - -- ----
*>
*>  If any eigenvectors are computed (either JOBVL='V' or JOBVR='V' or
*>  both), then on exit the arrays A and B will contain the real Schur
*>  form[*] of the "balanced" versions of A and B.  If no eigenvectors
*>  are computed, then only the diagonal blocks will be correct.
*>
*>  [*] See DHGEQZ, DGEGS, or read the book "Matrix Computations",
*>      by Golub & van Loan, pub. by Johns Hopkins U. Press.
*> \endverbatim
*>
*  =====================================================================
      SUBROUTINE DGEGV( JOBVL, JOBVR, N, A, LDA, B, LDB, ALPHAR, ALPHAI,
     $                  BETA, VL, LDVL, VR, LDVR, WORK, LWORK, INFO )
*
*  -- LAPACK driver routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      CHARACTER          JOBVL, JOBVR
      INTEGER            INFO, LDA, LDB, LDVL, LDVR, LWORK, N
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   A( LDA, * ), ALPHAI( * ), ALPHAR( * ),
     $                   B( LDB, * ), BETA( * ), VL( LDVL, * ),
     $                   VR( LDVR, * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ZERO, ONE
      PARAMETER          ( ZERO = 0.0D0, ONE = 1.0D0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            ILIMIT, ILV, ILVL, ILVR, LQUERY
      CHARACTER          CHTEMP
      INTEGER            ICOLS, IHI, IINFO, IJOBVL, IJOBVR, ILEFT, ILO,
     $                   IN, IRIGHT, IROWS, ITAU, IWORK, JC, JR, LOPT,
     $                   LWKMIN, LWKOPT, NB, NB1, NB2, NB3
      DOUBLE PRECISION   ABSAI, ABSAR, ABSB, ANRM, ANRM1, ANRM2, BNRM,
     $                   BNRM1, BNRM2, EPS, ONEPLS, SAFMAX, SAFMIN,
     $                   SALFAI, SALFAR, SBETA, SCALE, TEMP
*     ..
*     .. Local Arrays ..
      LOGICAL            LDUMMA( 1 )
*     ..
*     .. External Subroutines ..
      EXTERNAL           DGEQRF, DGGBAK, DGGBAL, DGGHRD, DHGEQZ, DLACPY,
     $                   DLASCL, DLASET, DORGQR, DORMQR, DTGEVC, XERBLA
*     ..
*     .. External Functions ..
      LOGICAL            LSAME
      INTEGER            ILAENV
      DOUBLE PRECISION   DLAMCH, DLANGE
      EXTERNAL           LSAME, ILAENV, DLAMCH, DLANGE
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          ABS, INT, MAX
*     ..
*     .. Executable Statements ..
*
*     Decode the input arguments
*
      IF( LSAME( JOBVL, 'N' ) ) THEN
         IJOBVL = 1
         ILVL = .FALSE.
      ELSE IF( LSAME( JOBVL, 'V' ) ) THEN
         IJOBVL = 2
         ILVL = .TRUE.
      ELSE
         IJOBVL = -1
         ILVL = .FALSE.
      END IF
*
      IF( LSAME( JOBVR, 'N' ) ) THEN
         IJOBVR = 1
         ILVR = .FALSE.
      ELSE IF( LSAME( JOBVR, 'V' ) ) THEN
         IJOBVR = 2
         ILVR = .TRUE.
      ELSE
         IJOBVR = -1
         ILVR = .FALSE.
      END IF
      ILV = ILVL .OR. ILVR
*
*     Test the input arguments
*
      LWKMIN = MAX( 8*N, 1 )
      LWKOPT = LWKMIN
      WORK( 1 ) = LWKOPT
      LQUERY = ( LWORK.EQ.-1 )
      INFO = 0
      IF( IJOBVL.LE.0 ) THEN
         INFO = -1
      ELSE IF( IJOBVR.LE.0 ) THEN
         INFO = -2
      ELSE IF( N.LT.0 ) THEN
         INFO = -3
      ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
         INFO = -5
      ELSE IF( LDB.LT.MAX( 1, N ) ) THEN
         INFO = -7
      ELSE IF( LDVL.LT.1 .OR. ( ILVL .AND. LDVL.LT.N ) ) THEN
         INFO = -12
      ELSE IF( LDVR.LT.1 .OR. ( ILVR .AND. LDVR.LT.N ) ) THEN
         INFO = -14
      ELSE IF( LWORK.LT.LWKMIN .AND. .NOT.LQUERY ) THEN
         INFO = -16
      END IF
*
      IF( INFO.EQ.0 ) THEN
         NB1 = ILAENV( 1, 'DGEQRF', ' ', N, N, -1, -1 )
         NB2 = ILAENV( 1, 'DORMQR', ' ', N, N, N, -1 )
         NB3 = ILAENV( 1, 'DORGQR', ' ', N, N, N, -1 )
         NB = MAX( NB1, NB2, NB3 )
         LOPT = 2*N + MAX( 6*N, N*( NB+1 ) )
         WORK( 1 ) = LOPT
      END IF
*
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGEGV ', -INFO )
         RETURN
      ELSE IF( LQUERY ) THEN
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( N.EQ.0 )
     $   RETURN
*
*     Get machine constants
*
      EPS = DLAMCH( 'E' )*DLAMCH( 'B' )
      SAFMIN = DLAMCH( 'S' )
      SAFMIN = SAFMIN + SAFMIN
      SAFMAX = ONE / SAFMIN
      ONEPLS = ONE + ( 4*EPS )
*
*     Scale A
*
      ANRM = DLANGE( 'M', N, N, A, LDA, WORK )
      ANRM1 = ANRM
      ANRM2 = ONE
      IF( ANRM.LT.ONE ) THEN
         IF( SAFMAX*ANRM.LT.ONE ) THEN
            ANRM1 = SAFMIN
            ANRM2 = SAFMAX*ANRM
         END IF
      END IF
*
      IF( ANRM.GT.ZERO ) THEN
         CALL DLASCL( 'G', -1, -1, ANRM, ONE, N, N, A, LDA, IINFO )
         IF( IINFO.NE.0 ) THEN
            INFO = N + 10
            RETURN
         END IF
      END IF
*
*     Scale B
*
      BNRM = DLANGE( 'M', N, N, B, LDB, WORK )
      BNRM1 = BNRM
      BNRM2 = ONE
      IF( BNRM.LT.ONE ) THEN
         IF( SAFMAX*BNRM.LT.ONE ) THEN
            BNRM1 = SAFMIN
            BNRM2 = SAFMAX*BNRM
         END IF
      END IF
*
      IF( BNRM.GT.ZERO ) THEN
         CALL DLASCL( 'G', -1, -1, BNRM, ONE, N, N, B, LDB, IINFO )
         IF( IINFO.NE.0 ) THEN
            INFO = N + 10
            RETURN
         END IF
      END IF
*
*     Permute the matrix to make it more nearly triangular
*     Workspace layout:  (8*N words -- "work" requires 6*N words)
*        left_permutation, right_permutation, work...
*
      ILEFT = 1
      IRIGHT = N + 1
      IWORK = IRIGHT + N
      CALL DGGBAL( 'P', N, A, LDA, B, LDB, ILO, IHI, WORK( ILEFT ),
     $             WORK( IRIGHT ), WORK( IWORK ), IINFO )
      IF( IINFO.NE.0 ) THEN
         INFO = N + 1
         GO TO 120
      END IF
*
*     Reduce B to triangular form, and initialize VL and/or VR
*     Workspace layout:  ("work..." must have at least N words)
*        left_permutation, right_permutation, tau, work...
*
      IROWS = IHI + 1 - ILO
      IF( ILV ) THEN
         ICOLS = N + 1 - ILO
      ELSE
         ICOLS = IROWS
      END IF
      ITAU = IWORK
      IWORK = ITAU + IROWS
      CALL DGEQRF( IROWS, ICOLS, B( ILO, ILO ), LDB, WORK( ITAU ),
     $             WORK( IWORK ), LWORK+1-IWORK, IINFO )
      IF( IINFO.GE.0 )
     $   LWKOPT = MAX( LWKOPT, INT( WORK( IWORK ) )+IWORK-1 )
      IF( IINFO.NE.0 ) THEN
         INFO = N + 2
         GO TO 120
      END IF
*
      CALL DORMQR( 'L', 'T', IROWS, ICOLS, IROWS, B( ILO, ILO ), LDB,
     $             WORK( ITAU ), A( ILO, ILO ), LDA, WORK( IWORK ),
     $             LWORK+1-IWORK, IINFO )
      IF( IINFO.GE.0 )
     $   LWKOPT = MAX( LWKOPT, INT( WORK( IWORK ) )+IWORK-1 )
      IF( IINFO.NE.0 ) THEN
         INFO = N + 3
         GO TO 120
      END IF
*
      IF( ILVL ) THEN
         CALL DLASET( 'Full', N, N, ZERO, ONE, VL, LDVL )
         CALL DLACPY( 'L', IROWS-1, IROWS-1, B( ILO+1, ILO ), LDB,
     $                VL( ILO+1, ILO ), LDVL )
         CALL DORGQR( IROWS, IROWS, IROWS, VL( ILO, ILO ), LDVL,
     $                WORK( ITAU ), WORK( IWORK ), LWORK+1-IWORK,
     $                IINFO )
         IF( IINFO.GE.0 )
     $      LWKOPT = MAX( LWKOPT, INT( WORK( IWORK ) )+IWORK-1 )
         IF( IINFO.NE.0 ) THEN
            INFO = N + 4
            GO TO 120
         END IF
      END IF
*
      IF( ILVR )
     $   CALL DLASET( 'Full', N, N, ZERO, ONE, VR, LDVR )
*
*     Reduce to generalized Hessenberg form
*
      IF( ILV ) THEN
*
*        Eigenvectors requested -- work on whole matrix.
*
         CALL DGGHRD( JOBVL, JOBVR, N, ILO, IHI, A, LDA, B, LDB, VL,
     $                LDVL, VR, LDVR, IINFO )
      ELSE
         CALL DGGHRD( 'N', 'N', IROWS, 1, IROWS, A( ILO, ILO ), LDA,
     $                B( ILO, ILO ), LDB, VL, LDVL, VR, LDVR, IINFO )
      END IF
      IF( IINFO.NE.0 ) THEN
         INFO = N + 5
         GO TO 120
      END IF
*
*     Perform QZ algorithm
*     Workspace layout:  ("work..." must have at least 1 word)
*        left_permutation, right_permutation, work...
*
      IWORK = ITAU
      IF( ILV ) THEN
         CHTEMP = 'S'
      ELSE
         CHTEMP = 'E'
      END IF
      CALL DHGEQZ( CHTEMP, JOBVL, JOBVR, N, ILO, IHI, A, LDA, B, LDB,
     $             ALPHAR, ALPHAI, BETA, VL, LDVL, VR, LDVR,
     $             WORK( IWORK ), LWORK+1-IWORK, IINFO )
      IF( IINFO.GE.0 )
     $   LWKOPT = MAX( LWKOPT, INT( WORK( IWORK ) )+IWORK-1 )
      IF( IINFO.NE.0 ) THEN
         IF( IINFO.GT.0 .AND. IINFO.LE.N ) THEN
            INFO = IINFO
         ELSE IF( IINFO.GT.N .AND. IINFO.LE.2*N ) THEN
            INFO = IINFO - N
         ELSE
            INFO = N + 6
         END IF
         GO TO 120
      END IF
*
      IF( ILV ) THEN
*
*        Compute Eigenvectors  (DTGEVC requires 6*N words of workspace)
*
         IF( ILVL ) THEN
            IF( ILVR ) THEN
               CHTEMP = 'B'
            ELSE
               CHTEMP = 'L'
            END IF
         ELSE
            CHTEMP = 'R'
         END IF
*
         CALL DTGEVC( CHTEMP, 'B', LDUMMA, N, A, LDA, B, LDB, VL, LDVL,
     $                VR, LDVR, N, IN, WORK( IWORK ), IINFO )
         IF( IINFO.NE.0 ) THEN
            INFO = N + 7
            GO TO 120
         END IF
*
*        Undo balancing on VL and VR, rescale
*
         IF( ILVL ) THEN
            CALL DGGBAK( 'P', 'L', N, ILO, IHI, WORK( ILEFT ),
     $                   WORK( IRIGHT ), N, VL, LDVL, IINFO )
            IF( IINFO.NE.0 ) THEN
               INFO = N + 8
               GO TO 120
            END IF
            DO 50 JC = 1, N
               IF( ALPHAI( JC ).LT.ZERO )
     $            GO TO 50
               TEMP = ZERO
               IF( ALPHAI( JC ).EQ.ZERO ) THEN
                  DO 10 JR = 1, N
                     TEMP = MAX( TEMP, ABS( VL( JR, JC ) ) )
   10             CONTINUE
               ELSE
                  DO 20 JR = 1, N
                     TEMP = MAX( TEMP, ABS( VL( JR, JC ) )+
     $                      ABS( VL( JR, JC+1 ) ) )
   20             CONTINUE
               END IF
               IF( TEMP.LT.SAFMIN )
     $            GO TO 50
               TEMP = ONE / TEMP
               IF( ALPHAI( JC ).EQ.ZERO ) THEN
                  DO 30 JR = 1, N
                     VL( JR, JC ) = VL( JR, JC )*TEMP
   30             CONTINUE
               ELSE
                  DO 40 JR = 1, N
                     VL( JR, JC ) = VL( JR, JC )*TEMP
                     VL( JR, JC+1 ) = VL( JR, JC+1 )*TEMP
   40             CONTINUE
               END IF
   50       CONTINUE
         END IF
         IF( ILVR ) THEN
            CALL DGGBAK( 'P', 'R', N, ILO, IHI, WORK( ILEFT ),
     $                   WORK( IRIGHT ), N, VR, LDVR, IINFO )
            IF( IINFO.NE.0 ) THEN
               INFO = N + 9
               GO TO 120
            END IF
            DO 100 JC = 1, N
               IF( ALPHAI( JC ).LT.ZERO )
     $            GO TO 100
               TEMP = ZERO
               IF( ALPHAI( JC ).EQ.ZERO ) THEN
                  DO 60 JR = 1, N
                     TEMP = MAX( TEMP, ABS( VR( JR, JC ) ) )
   60             CONTINUE
               ELSE
                  DO 70 JR = 1, N
                     TEMP = MAX( TEMP, ABS( VR( JR, JC ) )+
     $                      ABS( VR( JR, JC+1 ) ) )
   70             CONTINUE
               END IF
               IF( TEMP.LT.SAFMIN )
     $            GO TO 100
               TEMP = ONE / TEMP
               IF( ALPHAI( JC ).EQ.ZERO ) THEN
                  DO 80 JR = 1, N
                     VR( JR, JC ) = VR( JR, JC )*TEMP
   80             CONTINUE
               ELSE
                  DO 90 JR = 1, N
                     VR( JR, JC ) = VR( JR, JC )*TEMP
                     VR( JR, JC+1 ) = VR( JR, JC+1 )*TEMP
   90             CONTINUE
               END IF
  100       CONTINUE
         END IF
*
*        End of eigenvector calculation
*
      END IF
*
*     Undo scaling in alpha, beta
*
*     Note: this does not give the alpha and beta for the unscaled
*     problem.
*
*     Un-scaling is limited to avoid underflow in alpha and beta
*     if they are significant.
*
      DO 110 JC = 1, N
         ABSAR = ABS( ALPHAR( JC ) )
         ABSAI = ABS( ALPHAI( JC ) )
         ABSB = ABS( BETA( JC ) )
         SALFAR = ANRM*ALPHAR( JC )
         SALFAI = ANRM*ALPHAI( JC )
         SBETA = BNRM*BETA( JC )
         ILIMIT = .FALSE.
         SCALE = ONE
*
*        Check for significant underflow in ALPHAI
*
         IF( ABS( SALFAI ).LT.SAFMIN .AND. ABSAI.GE.
     $       MAX( SAFMIN, EPS*ABSAR, EPS*ABSB ) ) THEN
            ILIMIT = .TRUE.
            SCALE = ( ONEPLS*SAFMIN / ANRM1 ) /
     $              MAX( ONEPLS*SAFMIN, ANRM2*ABSAI )
*
         ELSE IF( SALFAI.EQ.ZERO ) THEN
*
*           If insignificant underflow in ALPHAI, then make the
*           conjugate eigenvalue real.
*
            IF( ALPHAI( JC ).LT.ZERO .AND. JC.GT.1 ) THEN
               ALPHAI( JC-1 ) = ZERO
            ELSE IF( ALPHAI( JC ).GT.ZERO .AND. JC.LT.N ) THEN
               ALPHAI( JC+1 ) = ZERO
            END IF
         END IF
*
*        Check for significant underflow in ALPHAR
*
         IF( ABS( SALFAR ).LT.SAFMIN .AND. ABSAR.GE.
     $       MAX( SAFMIN, EPS*ABSAI, EPS*ABSB ) ) THEN
            ILIMIT = .TRUE.
            SCALE = MAX( SCALE, ( ONEPLS*SAFMIN / ANRM1 ) /
     $              MAX( ONEPLS*SAFMIN, ANRM2*ABSAR ) )
         END IF
*
*        Check for significant underflow in BETA
*
         IF( ABS( SBETA ).LT.SAFMIN .AND. ABSB.GE.
     $       MAX( SAFMIN, EPS*ABSAR, EPS*ABSAI ) ) THEN
            ILIMIT = .TRUE.
            SCALE = MAX( SCALE, ( ONEPLS*SAFMIN / BNRM1 ) /
     $              MAX( ONEPLS*SAFMIN, BNRM2*ABSB ) )
         END IF
*
*        Check for possible overflow when limiting scaling
*
         IF( ILIMIT ) THEN
            TEMP = ( SCALE*SAFMIN )*MAX( ABS( SALFAR ), ABS( SALFAI ),
     $             ABS( SBETA ) )
            IF( TEMP.GT.ONE )
     $         SCALE = SCALE / TEMP
            IF( SCALE.LT.ONE )
     $         ILIMIT = .FALSE.
         END IF
*
*        Recompute un-scaled ALPHAR, ALPHAI, BETA if necessary.
*
         IF( ILIMIT ) THEN
            SALFAR = ( SCALE*ALPHAR( JC ) )*ANRM
            SALFAI = ( SCALE*ALPHAI( JC ) )*ANRM
            SBETA = ( SCALE*BETA( JC ) )*BNRM
         END IF
         ALPHAR( JC ) = SALFAR
         ALPHAI( JC ) = SALFAI
         BETA( JC ) = SBETA
  110 CONTINUE
*
  120 CONTINUE
      WORK( 1 ) = LWKOPT
*
      RETURN
*
*     End of DGEGV
*
      END
*> \brief \b DGEHD2 reduces a general square matrix to upper Hessenberg form using an unblocked algorithm.
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGEHD2 + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgehd2.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgehd2.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgehd2.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGEHD2( N, ILO, IHI, A, LDA, TAU, WORK, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            IHI, ILO, INFO, LDA, N
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGEHD2 reduces a real general matrix A to upper Hessenberg form H by
*> an orthogonal similarity transformation:  Q**T * A * Q = H .
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The order of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in] ILO
*> \verbatim
*>          ILO is INTEGER
*> \endverbatim
*>
*> \param[in] IHI
*> \verbatim
*>          IHI is INTEGER
*>
*>          It is assumed that A is already upper triangular in rows
*>          and columns 1:ILO-1 and IHI+1:N. ILO and IHI are normally
*>          set by a previous call to DGEBAL; otherwise they should be
*>          set to 1 and N respectively. See Further Details.
*>          1 <= ILO <= IHI <= max(1,N).
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the n by n general matrix to be reduced.
*>          On exit, the upper triangle and the first subdiagonal of A
*>          are overwritten with the upper Hessenberg matrix H, and the
*>          elements below the first subdiagonal, with the array TAU,
*>          represent the orthogonal matrix Q as a product of elementary
*>          reflectors. See Further Details.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,N).
*> \endverbatim
*>
*> \param[out] TAU
*> \verbatim
*>          TAU is DOUBLE PRECISION array, dimension (N-1)
*>          The scalar factors of the elementary reflectors (see Further
*>          Details).
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (N)
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit.
*>          < 0:  if INFO = -i, the i-th argument had an illegal value.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEcomputational
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>  The matrix Q is represented as a product of (ihi-ilo) elementary
*>  reflectors
*>
*>     Q = H(ilo) H(ilo+1) . . . H(ihi-1).
*>
*>  Each H(i) has the form
*>
*>     H(i) = I - tau * v * v**T
*>
*>  where tau is a real scalar, and v is a real vector with
*>  v(1:i) = 0, v(i+1) = 1 and v(ihi+1:n) = 0; v(i+2:ihi) is stored on
*>  exit in A(i+2:ihi,i), and tau in TAU(i).
*>
*>  The contents of A are illustrated by the following example, with
*>  n = 7, ilo = 2 and ihi = 6:
*>
*>  on entry,                        on exit,
*>
*>  ( a   a   a   a   a   a   a )    (  a   a   h   h   h   h   a )
*>  (     a   a   a   a   a   a )    (      a   h   h   h   h   a )
*>  (     a   a   a   a   a   a )    (      h   h   h   h   h   h )
*>  (     a   a   a   a   a   a )    (      v2  h   h   h   h   h )
*>  (     a   a   a   a   a   a )    (      v2  v3  h   h   h   h )
*>  (     a   a   a   a   a   a )    (      v2  v3  v4  h   h   h )
*>  (                         a )    (                          a )
*>
*>  where a denotes an element of the original matrix A, h denotes a
*>  modified element of the upper Hessenberg matrix H, and vi denotes an
*>  element of the vector defining H(i).
*> \endverbatim
*>
*  =====================================================================
      SUBROUTINE DGEHD2( N, ILO, IHI, A, LDA, TAU, WORK, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER            IHI, ILO, INFO, LDA, N
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ONE
      PARAMETER          ( ONE = 1.0D+0 )
*     ..
*     .. Local Scalars ..
      INTEGER            I
      DOUBLE PRECISION   AII
*     ..
*     .. External Subroutines ..
      EXTERNAL           DLARF, DLARFG, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, MIN
*     ..
*     .. Executable Statements ..
*
*     Test the input parameters
*
      INFO = 0
      IF( N.LT.0 ) THEN
         INFO = -1
      ELSE IF( ILO.LT.1 .OR. ILO.GT.MAX( 1, N ) ) THEN
         INFO = -2
      ELSE IF( IHI.LT.MIN( ILO, N ) .OR. IHI.GT.N ) THEN
         INFO = -3
      ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
         INFO = -5
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGEHD2', -INFO )
         RETURN
      END IF
*
      DO 10 I = ILO, IHI - 1
*
*        Compute elementary reflector H(i) to annihilate A(i+2:ihi,i)
*
         CALL DLARFG( IHI-I, A( I+1, I ), A( MIN( I+2, N ), I ), 1,
     $                TAU( I ) )
         AII = A( I+1, I )
         A( I+1, I ) = ONE
*
*        Apply H(i) to A(1:ihi,i+1:ihi) from the right
*
         CALL DLARF( 'Right', IHI, IHI-I, A( I+1, I ), 1, TAU( I ),
     $               A( 1, I+1 ), LDA, WORK )
*
*        Apply H(i) to A(i+1:ihi,i+1:n) from the left
*
         CALL DLARF( 'Left', IHI-I, N-I, A( I+1, I ), 1, TAU( I ),
     $               A( I+1, I+1 ), LDA, WORK )
*
         A( I+1, I ) = AII
   10 CONTINUE
*
      RETURN
*
*     End of DGEHD2
*
      END
*> \brief \b DGEHRD
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGEHRD + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgehrd.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgehrd.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgehrd.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGEHRD( N, ILO, IHI, A, LDA, TAU, WORK, LWORK, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            IHI, ILO, INFO, LDA, LWORK, N
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION  A( LDA, * ), TAU( * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGEHRD reduces a real general matrix A to upper Hessenberg form H by
*> an orthogonal similarity transformation:  Q**T * A * Q = H .
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The order of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in] ILO
*> \verbatim
*>          ILO is INTEGER
*> \endverbatim
*>
*> \param[in] IHI
*> \verbatim
*>          IHI is INTEGER
*>
*>          It is assumed that A is already upper triangular in rows
*>          and columns 1:ILO-1 and IHI+1:N. ILO and IHI are normally
*>          set by a previous call to DGEBAL; otherwise they should be
*>          set to 1 and N respectively. See Further Details.
*>          1 <= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the N-by-N general matrix to be reduced.
*>          On exit, the upper triangle and the first subdiagonal of A
*>          are overwritten with the upper Hessenberg matrix H, and the
*>          elements below the first subdiagonal, with the array TAU,
*>          represent the orthogonal matrix Q as a product of elementary
*>          reflectors. See Further Details.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,N).
*> \endverbatim
*>
*> \param[out] TAU
*> \verbatim
*>          TAU is DOUBLE PRECISION array, dimension (N-1)
*>          The scalar factors of the elementary reflectors (see Further
*>          Details). Elements 1:ILO-1 and IHI:N-1 of TAU are set to
*>          zero.
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (LWORK)
*>          On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
*> \endverbatim
*>
*> \param[in] LWORK
*> \verbatim
*>          LWORK is INTEGER
*>          The length of the array WORK.  LWORK >= max(1,N).
*>          For good performance, LWORK should generally be larger.
*>
*>          If LWORK = -1, then a workspace query is assumed; the routine
*>          only calculates the optimal size of the WORK array, returns
*>          this value as the first entry of the WORK array, and no error
*>          message related to LWORK is issued by XERBLA.
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEcomputational
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>  The matrix Q is represented as a product of (ihi-ilo) elementary
*>  reflectors
*>
*>     Q = H(ilo) H(ilo+1) . . . H(ihi-1).
*>
*>  Each H(i) has the form
*>
*>     H(i) = I - tau * v * v**T
*>
*>  where tau is a real scalar, and v is a real vector with
*>  v(1:i) = 0, v(i+1) = 1 and v(ihi+1:n) = 0; v(i+2:ihi) is stored on
*>  exit in A(i+2:ihi,i), and tau in TAU(i).
*>
*>  The contents of A are illustrated by the following example, with
*>  n = 7, ilo = 2 and ihi = 6:
*>
*>  on entry,                        on exit,
*>
*>  ( a   a   a   a   a   a   a )    (  a   a   h   h   h   h   a )
*>  (     a   a   a   a   a   a )    (      a   h   h   h   h   a )
*>  (     a   a   a   a   a   a )    (      h   h   h   h   h   h )
*>  (     a   a   a   a   a   a )    (      v2  h   h   h   h   h )
*>  (     a   a   a   a   a   a )    (      v2  v3  h   h   h   h )
*>  (     a   a   a   a   a   a )    (      v2  v3  v4  h   h   h )
*>  (                         a )    (                          a )
*>
*>  where a denotes an element of the original matrix A, h denotes a
*>  modified element of the upper Hessenberg matrix H, and vi denotes an
*>  element of the vector defining H(i).
*>
*>  This file is a slight modification of LAPACK-3.0's DGEHRD
*>  subroutine incorporating improvements proposed by Quintana-Orti and
*>  Van de Geijn (2006). (See DLAHR2.)
*> \endverbatim
*>
*  =====================================================================
      SUBROUTINE DGEHRD( N, ILO, IHI, A, LDA, TAU, WORK, LWORK, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER            IHI, ILO, INFO, LDA, LWORK, N
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION  A( LDA, * ), TAU( * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      INTEGER            NBMAX, LDT, TSIZE
      PARAMETER          ( NBMAX = 64, LDT = NBMAX+1,
     $                     TSIZE = LDT*NBMAX )
      DOUBLE PRECISION  ZERO, ONE
      PARAMETER          ( ZERO = 0.0D+0,
     $                     ONE = 1.0D+0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            LQUERY
      INTEGER            I, IB, IINFO, IWT, J, LDWORK, LWKOPT, NB,
     $                   NBMIN, NH, NX
      DOUBLE PRECISION  EI
*     ..
*     .. External Subroutines ..
      EXTERNAL           DAXPY, DGEHD2, DGEMM, DLAHR2, DLARFB, DTRMM,
     $                   XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, MIN
*     ..
*     .. External Functions ..
      INTEGER            ILAENV
      EXTERNAL           ILAENV
*     ..
*     .. Executable Statements ..
*
*     Test the input parameters
*
      INFO = 0
      LQUERY = ( LWORK.EQ.-1 )
      IF( N.LT.0 ) THEN
         INFO = -1
      ELSE IF( ILO.LT.1 .OR. ILO.GT.MAX( 1, N ) ) THEN
         INFO = -2
      ELSE IF( IHI.LT.MIN( ILO, N ) .OR. IHI.GT.N ) THEN
         INFO = -3
      ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
         INFO = -5
      ELSE IF( LWORK.LT.MAX( 1, N ) .AND. .NOT.LQUERY ) THEN
         INFO = -8
      END IF
*
      IF( INFO.EQ.0 ) THEN
*
*        Compute the workspace requirements
*
         NB = MIN( NBMAX, ILAENV( 1, 'DGEHRD', ' ', N, ILO, IHI, -1 ) )
         LWKOPT = N*NB + TSIZE
         WORK( 1 ) = LWKOPT
      END IF
*
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGEHRD', -INFO )
         RETURN
      ELSE IF( LQUERY ) THEN
         RETURN
      END IF
*
*     Set elements 1:ILO-1 and IHI:N-1 of TAU to zero
*
      DO 10 I = 1, ILO - 1
         TAU( I ) = ZERO
   10 CONTINUE
      DO 20 I = MAX( 1, IHI ), N - 1
         TAU( I ) = ZERO
   20 CONTINUE
*
*     Quick return if possible
*
      NH = IHI - ILO + 1
      IF( NH.LE.1 ) THEN
         WORK( 1 ) = 1
         RETURN
      END IF
*
*     Determine the block size
*
      NB = MIN( NBMAX, ILAENV( 1, 'DGEHRD', ' ', N, ILO, IHI, -1 ) )
      NBMIN = 2
      IF( NB.GT.1 .AND. NB.LT.NH ) THEN
*
*        Determine when to cross over from blocked to unblocked code
*        (last block is always handled by unblocked code)
*
         NX = MAX( NB, ILAENV( 3, 'DGEHRD', ' ', N, ILO, IHI, -1 ) )
         IF( NX.LT.NH ) THEN
*
*           Determine if workspace is large enough for blocked code
*
            IF( LWORK.LT.N*NB+TSIZE ) THEN
*
*              Not enough workspace to use optimal NB:  determine the
*              minimum value of NB, and reduce NB or force use of
*              unblocked code
*
               NBMIN = MAX( 2, ILAENV( 2, 'DGEHRD', ' ', N, ILO, IHI,
     $                 -1 ) )
               IF( LWORK.GE.(N*NBMIN + TSIZE) ) THEN
                  NB = (LWORK-TSIZE) / N
               ELSE
                  NB = 1
               END IF
            END IF
         END IF
      END IF
      LDWORK = N
*
      IF( NB.LT.NBMIN .OR. NB.GE.NH ) THEN
*
*        Use unblocked code below
*
         I = ILO
*
      ELSE
*
*        Use blocked code
*
         IWT = 1 + N*NB
         DO 40 I = ILO, IHI - 1 - NX, NB
            IB = MIN( NB, IHI-I )
*
*           Reduce columns i:i+ib-1 to Hessenberg form, returning the
*           matrices V and T of the block reflector H = I - V*T*V**T
*           which performs the reduction, and also the matrix Y = A*V*T
*
            CALL DLAHR2( IHI, I, IB, A( 1, I ), LDA, TAU( I ),
     $                   WORK( IWT ), LDT, WORK, LDWORK )
*
*           Apply the block reflector H to A(1:ihi,i+ib:ihi) from the
*           right, computing  A := A - Y * V**T. V(i+ib,ib-1) must be set
*           to 1
*
            EI = A( I+IB, I+IB-1 )
            A( I+IB, I+IB-1 ) = ONE
            CALL DGEMM( 'No transpose', 'Transpose',
     $                  IHI, IHI-I-IB+1,
     $                  IB, -ONE, WORK, LDWORK, A( I+IB, I ), LDA, ONE,
     $                  A( 1, I+IB ), LDA )
            A( I+IB, I+IB-1 ) = EI
*
*           Apply the block reflector H to A(1:i,i+1:i+ib-1) from the
*           right
*
            CALL DTRMM( 'Right', 'Lower', 'Transpose',
     $                  'Unit', I, IB-1,
     $                  ONE, A( I+1, I ), LDA, WORK, LDWORK )
            DO 30 J = 0, IB-2
               CALL DAXPY( I, -ONE, WORK( LDWORK*J+1 ), 1,
     $                     A( 1, I+J+1 ), 1 )
   30       CONTINUE
*
*           Apply the block reflector H to A(i+1:ihi,i+ib:n) from the
*           left
*
            CALL DLARFB( 'Left', 'Transpose', 'Forward',
     $                   'Columnwise',
     $                   IHI-I, N-I-IB+1, IB, A( I+1, I ), LDA,
     $                   WORK( IWT ), LDT, A( I+1, I+IB ), LDA,
     $                   WORK, LDWORK )
   40    CONTINUE
      END IF
*
*     Use unblocked code to reduce the rest of the matrix
*
      CALL DGEHD2( N, I, IHI, A, LDA, TAU, WORK, IINFO )
      WORK( 1 ) = LWKOPT
*
      RETURN
*
*     End of DGEHRD
*
      END
*> \brief \b DGEJSV
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGEJSV + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgejsv.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgejsv.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgejsv.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGEJSV( JOBA, JOBU, JOBV, JOBR, JOBT, JOBP,
*                          M, N, A, LDA, SVA, U, LDU, V, LDV,
*                          WORK, LWORK, IWORK, INFO )
*
*       .. Scalar Arguments ..
*       IMPLICIT    NONE
*       INTEGER     INFO, LDA, LDU, LDV, LWORK, M, N
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION A( LDA, * ), SVA( N ), U( LDU, * ), V( LDV, * ),
*      $            WORK( LWORK )
*       INTEGER     IWORK( * )
*       CHARACTER*1 JOBA, JOBP, JOBR, JOBT, JOBU, JOBV
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGEJSV computes the singular value decomposition (SVD) of a real M-by-N
*> matrix [A], where M >= N. The SVD of [A] is written as
*>
*>              [A] = [U] * [SIGMA] * [V]^t,
*>
*> where [SIGMA] is an N-by-N (M-by-N) matrix which is zero except for its N
*> diagonal elements, [U] is an M-by-N (or M-by-M) orthonormal matrix, and
*> [V] is an N-by-N orthogonal matrix. The diagonal elements of [SIGMA] are
*> the singular values of [A]. The columns of [U] and [V] are the left and
*> the right singular vectors of [A], respectively. The matrices [U] and [V]
*> are computed and stored in the arrays U and V, respectively. The diagonal
*> of [SIGMA] is computed and stored in the array SVA.
*> DGEJSV can sometimes compute tiny singular values and their singular vectors much
*> more accurately than other SVD routines, see below under Further Details.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] JOBA
*> \verbatim
*>          JOBA is CHARACTER*1
*>        Specifies the level of accuracy:
*>       = 'C': This option works well (high relative accuracy) if A = B * D,
*>             with well-conditioned B and arbitrary diagonal matrix D.
*>             The accuracy cannot be spoiled by COLUMN scaling. The
*>             accuracy of the computed output depends on the condition of
*>             B, and the procedure aims at the best theoretical accuracy.
*>             The relative error max_{i=1:N}|d sigma_i| / sigma_i is
*>             bounded by f(M,N)*epsilon* cond(B), independent of D.
*>             The input matrix is preprocessed with the QRF with column
*>             pivoting. This initial preprocessing and preconditioning by
*>             a rank revealing QR factorization is common for all values of
*>             JOBA. Additional actions are specified as follows:
*>       = 'E': Computation as with 'C' with an additional estimate of the
*>             condition number of B. It provides a realistic error bound.
*>       = 'F': If A = D1 * C * D2 with ill-conditioned diagonal scalings
*>             D1, D2, and well-conditioned matrix C, this option gives
*>             higher accuracy than the 'C' option. If the structure of the
*>             input matrix is not known, and relative accuracy is
*>             desirable, then this option is advisable. The input matrix A
*>             is preprocessed with QR factorization with FULL (row and
*>             column) pivoting.
*>       = 'G'  Computation as with 'F' with an additional estimate of the
*>             condition number of B, where A=D*B. If A has heavily weighted
*>             rows, then using this condition number gives too pessimistic
*>             error bound.
*>       = 'A': Small singular values are the noise and the matrix is treated
*>             as numerically rank deficient. The error in the computed
*>             singular values is bounded by f(m,n)*epsilon*||A||.
*>             The computed SVD A = U * S * V^t restores A up to
*>             f(m,n)*epsilon*||A||.
*>             This gives the procedure the licence to discard (set to zero)
*>             all singular values below N*epsilon*||A||.
*>       = 'R': Similar as in 'A'. Rank revealing property of the initial
*>             QR factorization is used do reveal (using triangular factor)
*>             a gap sigma_{r+1} < epsilon * sigma_r in which case the
*>             numerical RANK is declared to be r. The SVD is computed with
*>             absolute error bounds, but more accurately than with 'A'.
*> \endverbatim
*>
*> \param[in] JOBU
*> \verbatim
*>          JOBU is CHARACTER*1
*>        Specifies whether to compute the columns of U:
*>       = 'U': N columns of U are returned in the array U.
*>       = 'F': full set of M left sing. vectors is returned in the array U.
*>       = 'W': U may be used as workspace of length M*N. See the description
*>             of U.
*>       = 'N': U is not computed.
*> \endverbatim
*>
*> \param[in] JOBV
*> \verbatim
*>          JOBV is CHARACTER*1
*>        Specifies whether to compute the matrix V:
*>       = 'V': N columns of V are returned in the array V; Jacobi rotations
*>             are not explicitly accumulated.
*>       = 'J': N columns of V are returned in the array V, but they are
*>             computed as the product of Jacobi rotations. This option is
*>             allowed only if JOBU .NE. 'N', i.e. in computing the full SVD.
*>       = 'W': V may be used as workspace of length N*N. See the description
*>             of V.
*>       = 'N': V is not computed.
*> \endverbatim
*>
*> \param[in] JOBR
*> \verbatim
*>          JOBR is CHARACTER*1
*>        Specifies the RANGE for the singular values. Issues the licence to
*>        set to zero small positive singular values if they are outside
*>        specified range. If A .NE. 0 is scaled so that the largest singular
*>        value of c*A is around DSQRT(BIG), BIG=SLAMCH('O'), then JOBR issues
*>        the licence to kill columns of A whose norm in c*A is less than
*>        DSQRT(SFMIN) (for JOBR.EQ.'R'), or less than SMALL=SFMIN/EPSLN,
*>        where SFMIN=SLAMCH('S'), EPSLN=SLAMCH('E').
*>       = 'N': Do not kill small columns of c*A. This option assumes that
*>             BLAS and QR factorizations and triangular solvers are
*>             implemented to work in that range. If the condition of A
*>             is greater than BIG, use DGESVJ.
*>       = 'R': RESTRICTED range for sigma(c*A) is [DSQRT(SFMIN), DSQRT(BIG)]
*>             (roughly, as described above). This option is recommended.
*>                                            ~~~~~~~~~~~~~~~~~~~~~~~~~~~
*>        For computing the singular values in the FULL range [SFMIN,BIG]
*>        use DGESVJ.
*> \endverbatim
*>
*> \param[in] JOBT
*> \verbatim
*>          JOBT is CHARACTER*1
*>        If the matrix is square then the procedure may determine to use
*>        transposed A if A^t seems to be better with respect to convergence.
*>        If the matrix is not square, JOBT is ignored. This is subject to
*>        changes in the future.
*>        The decision is based on two values of entropy over the adjoint
*>        orbit of A^t * A. See the descriptions of WORK(6) and WORK(7).
*>       = 'T': transpose if entropy test indicates possibly faster
*>        convergence of Jacobi process if A^t is taken as input. If A is
*>        replaced with A^t, then the row pivoting is included automatically.
*>       = 'N': do not speculate.
*>        This option can be used to compute only the singular values, or the
*>        full SVD (U, SIGMA and V). For only one set of singular vectors
*>        (U or V), the caller should provide both U and V, as one of the
*>        matrices is used as workspace if the matrix A is transposed.
*>        The implementer can easily remove this constraint and make the
*>        code more complicated. See the descriptions of U and V.
*> \endverbatim
*>
*> \param[in] JOBP
*> \verbatim
*>          JOBP is CHARACTER*1
*>        Issues the licence to introduce structured perturbations to drown
*>        denormalized numbers. This licence should be active if the
*>        denormals are poorly implemented, causing slow computation,
*>        especially in cases of fast convergence (!). For details see [1,2].
*>        For the sake of simplicity, this perturbations are included only
*>        when the full SVD or only the singular values are requested. The
*>        implementer/user can easily add the perturbation for the cases of
*>        computing one set of singular vectors.
*>       = 'P': introduce perturbation
*>       = 'N': do not perturb
*> \endverbatim
*>
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>         The number of rows of the input matrix A.  M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>         The number of columns of the input matrix A. M >= N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the M-by-N matrix A.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,M).
*> \endverbatim
*>
*> \param[out] SVA
*> \verbatim
*>          SVA is DOUBLE PRECISION array, dimension (N)
*>          On exit,
*>          - For WORK(1)/WORK(2) = ONE: The singular values of A. During the
*>            computation SVA contains Euclidean column norms of the
*>            iterated matrices in the array A.
*>          - For WORK(1) .NE. WORK(2): The singular values of A are
*>            (WORK(1)/WORK(2)) * SVA(1:N). This factored form is used if
*>            sigma_max(A) overflows or if small singular values have been
*>            saved from underflow by scaling the input matrix A.
*>          - If JOBR='R' then some of the singular values may be returned
*>            as exact zeros obtained by "set to zero" because they are
*>            below the numerical rank threshold or are denormalized numbers.
*> \endverbatim
*>
*> \param[out] U
*> \verbatim
*>          U is DOUBLE PRECISION array, dimension ( LDU, N )
*>          If JOBU = 'U', then U contains on exit the M-by-N matrix of
*>                         the left singular vectors.
*>          If JOBU = 'F', then U contains on exit the M-by-M matrix of
*>                         the left singular vectors, including an ONB
*>                         of the orthogonal complement of the Range(A).
*>          If JOBU = 'W'  .AND. (JOBV.EQ.'V' .AND. JOBT.EQ.'T' .AND. M.EQ.N),
*>                         then U is used as workspace if the procedure
*>                         replaces A with A^t. In that case, [V] is computed
*>                         in U as left singular vectors of A^t and then
*>                         copied back to the V array. This 'W' option is just
*>                         a reminder to the caller that in this case U is
*>                         reserved as workspace of length N*N.
*>          If JOBU = 'N'  U is not referenced, unless JOBT='T'.
*> \endverbatim
*>
*> \param[in] LDU
*> \verbatim
*>          LDU is INTEGER
*>          The leading dimension of the array U,  LDU >= 1.
*>          IF  JOBU = 'U' or 'F' or 'W',  then LDU >= M.
*> \endverbatim
*>
*> \param[out] V
*> \verbatim
*>          V is DOUBLE PRECISION array, dimension ( LDV, N )
*>          If JOBV = 'V', 'J' then V contains on exit the N-by-N matrix of
*>                         the right singular vectors;
*>          If JOBV = 'W', AND (JOBU.EQ.'U' AND JOBT.EQ.'T' AND M.EQ.N),
*>                         then V is used as workspace if the pprocedure
*>                         replaces A with A^t. In that case, [U] is computed
*>                         in V as right singular vectors of A^t and then
*>                         copied back to the U array. This 'W' option is just
*>                         a reminder to the caller that in this case V is
*>                         reserved as workspace of length N*N.
*>          If JOBV = 'N'  V is not referenced, unless JOBT='T'.
*> \endverbatim
*>
*> \param[in] LDV
*> \verbatim
*>          LDV is INTEGER
*>          The leading dimension of the array V,  LDV >= 1.
*>          If JOBV = 'V' or 'J' or 'W', then LDV >= N.
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (LWORK)
*>          On exit, if N.GT.0 .AND. M.GT.0 (else not referenced),
*>          WORK(1) = SCALE = WORK(2) / WORK(1) is the scaling factor such
*>                    that SCALE*SVA(1:N) are the computed singular values
*>                    of A. (See the description of SVA().)
*>          WORK(2) = See the description of WORK(1).
*>          WORK(3) = SCONDA is an estimate for the condition number of
*>                    column equilibrated A. (If JOBA .EQ. 'E' or 'G')
*>                    SCONDA is an estimate of DSQRT(||(R^t * R)^(-1)||_1).
*>                    It is computed using DPOCON. It holds
*>                    N^(-1/4) * SCONDA <= ||R^(-1)||_2 <= N^(1/4) * SCONDA
*>                    where R is the triangular factor from the QRF of A.
*>                    However, if R is truncated and the numerical rank is
*>                    determined to be strictly smaller than N, SCONDA is
*>                    returned as -1, thus indicating that the smallest
*>                    singular values might be lost.
*>
*>          If full SVD is needed, the following two condition numbers are
*>          useful for the analysis of the algorithm. They are provied for
*>          a developer/implementer who is familiar with the details of
*>          the method.
*>
*>          WORK(4) = an estimate of the scaled condition number of the
*>                    triangular factor in the first QR factorization.
*>          WORK(5) = an estimate of the scaled condition number of the
*>                    triangular factor in the second QR factorization.
*>          The following two parameters are computed if JOBT .EQ. 'T'.
*>          They are provided for a developer/implementer who is familiar
*>          with the details of the method.
*>
*>          WORK(6) = the entropy of A^t*A :: this is the Shannon entropy
*>                    of diag(A^t*A) / Trace(A^t*A) taken as point in the
*>                    probability simplex.
*>          WORK(7) = the entropy of A*A^t.
*> \endverbatim
*>
*> \param[in] LWORK
*> \verbatim
*>          LWORK is INTEGER
*>          Length of WORK to confirm proper allocation of work space.
*>          LWORK depends on the job:
*>
*>          If only SIGMA is needed ( JOBU.EQ.'N', JOBV.EQ.'N' ) and
*>            -> .. no scaled condition estimate required (JOBE.EQ.'N'):
*>               LWORK >= max(2*M+N,4*N+1,7). This is the minimal requirement.
*>               ->> For optimal performance (blocked code) the optimal value
*>               is LWORK >= max(2*M+N,3*N+(N+1)*NB,7). Here NB is the optimal
*>               block size for DGEQP3 and DGEQRF.
*>               In general, optimal LWORK is computed as
*>               LWORK >= max(2*M+N,N+LWORK(DGEQP3),N+LWORK(DGEQRF), 7).
*>            -> .. an estimate of the scaled condition number of A is
*>               required (JOBA='E', 'G'). In this case, LWORK is the maximum
*>               of the above and N*N+4*N, i.e. LWORK >= max(2*M+N,N*N+4*N,7).
*>               ->> For optimal performance (blocked code) the optimal value
*>               is LWORK >= max(2*M+N,3*N+(N+1)*NB, N*N+4*N, 7).
*>               In general, the optimal length LWORK is computed as
*>               LWORK >= max(2*M+N,N+LWORK(DGEQP3),N+LWORK(DGEQRF),
*>                                                     N+N*N+LWORK(DPOCON),7).
*>
*>          If SIGMA and the right singular vectors are needed (JOBV.EQ.'V'),
*>            -> the minimal requirement is LWORK >= max(2*M+N,4*N+1,7).
*>            -> For optimal performance, LWORK >= max(2*M+N,3*N+(N+1)*NB,7),
*>               where NB is the optimal block size for DGEQP3, DGEQRF, DGELQF,
*>               DORMLQ. In general, the optimal length LWORK is computed as
*>               LWORK >= max(2*M+N,N+LWORK(DGEQP3), N+LWORK(DPOCON),
*>                       N+LWORK(DGELQF), 2*N+LWORK(DGEQRF), N+LWORK(DORMLQ)).
*>
*>          If SIGMA and the left singular vectors are needed
*>            -> the minimal requirement is LWORK >= max(2*M+N,4*N+1,7).
*>            -> For optimal performance:
*>               if JOBU.EQ.'U' :: LWORK >= max(2*M+N,3*N+(N+1)*NB,7),
*>               if JOBU.EQ.'F' :: LWORK >= max(2*M+N,3*N+(N+1)*NB,N+M*NB,7),
*>               where NB is the optimal block size for DGEQP3, DGEQRF, DORMQR.
*>               In general, the optimal length LWORK is computed as
*>               LWORK >= max(2*M+N,N+LWORK(DGEQP3),N+LWORK(DPOCON),
*>                        2*N+LWORK(DGEQRF), N+LWORK(DORMQR)).
*>               Here LWORK(DORMQR) equals N*NB (for JOBU.EQ.'U') or
*>               M*NB (for JOBU.EQ.'F').
*>
*>          If the full SVD is needed: (JOBU.EQ.'U' or JOBU.EQ.'F') and
*>            -> if JOBV.EQ.'V'
*>               the minimal requirement is LWORK >= max(2*M+N,6*N+2*N*N).
*>            -> if JOBV.EQ.'J' the minimal requirement is
*>               LWORK >= max(2*M+N, 4*N+N*N,2*N+N*N+6).
*>            -> For optimal performance, LWORK should be additionally
*>               larger than N+M*NB, where NB is the optimal block size
*>               for DORMQR.
*> \endverbatim
*>
*> \param[out] IWORK
*> \verbatim
*>          IWORK is INTEGER array, dimension (M+3*N).
*>          On exit,
*>          IWORK(1) = the numerical rank determined after the initial
*>                     QR factorization with pivoting. See the descriptions
*>                     of JOBA and JOBR.
*>          IWORK(2) = the number of the computed nonzero singular values
*>          IWORK(3) = if nonzero, a warning message:
*>                     If IWORK(3).EQ.1 then some of the column norms of A
*>                     were denormalized floats. The requested high accuracy
*>                     is not warranted by the data.
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>           < 0  : if INFO = -i, then the i-th argument had an illegal value.
*>           = 0 :  successful exit;
*>           > 0 :  DGEJSV  did not converge in the maximal allowed number
*>                  of sweeps. The computed values may be inaccurate.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date June 2016
*
*> \ingroup doubleGEsing
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>  DGEJSV implements a preconditioned Jacobi SVD algorithm. It uses DGEQP3,
*>  DGEQRF, and DGELQF as preprocessors and preconditioners. Optionally, an
*>  additional row pivoting can be used as a preprocessor, which in some
*>  cases results in much higher accuracy. An example is matrix A with the
*>  structure A = D1 * C * D2, where D1, D2 are arbitrarily ill-conditioned
*>  diagonal matrices and C is well-conditioned matrix. In that case, complete
*>  pivoting in the first QR factorizations provides accuracy dependent on the
*>  condition number of C, and independent of D1, D2. Such higher accuracy is
*>  not completely understood theoretically, but it works well in practice.
*>  Further, if A can be written as A = B*D, with well-conditioned B and some
*>  diagonal D, then the high accuracy is guaranteed, both theoretically and
*>  in software, independent of D. For more details see [1], [2].
*>     The computational range for the singular values can be the full range
*>  ( UNDERFLOW,OVERFLOW ), provided that the machine arithmetic and the BLAS
*>  & LAPACK routines called by DGEJSV are implemented to work in that range.
*>  If that is not the case, then the restriction for safe computation with
*>  the singular values in the range of normalized IEEE numbers is that the
*>  spectral condition number kappa(A)=sigma_max(A)/sigma_min(A) does not
*>  overflow. This code (DGEJSV) is best used in this restricted range,
*>  meaning that singular values of magnitude below ||A||_2 / DLAMCH('O') are
*>  returned as zeros. See JOBR for details on this.
*>     Further, this implementation is somewhat slower than the one described
*>  in [1,2] due to replacement of some non-LAPACK components, and because
*>  the choice of some tuning parameters in the iterative part (DGESVJ) is
*>  left to the implementer on a particular machine.
*>     The rank revealing QR factorization (in this code: DGEQP3) should be
*>  implemented as in [3]. We have a new version of DGEQP3 under development
*>  that is more robust than the current one in LAPACK, with a cleaner cut in
*>  rank deficient cases. It will be available in the SIGMA library [4].
*>  If M is much larger than N, it is obvious that the initial QRF with
*>  column pivoting can be preprocessed by the QRF without pivoting. That
*>  well known trick is not used in DGEJSV because in some cases heavy row
*>  weighting can be treated with complete pivoting. The overhead in cases
*>  M much larger than N is then only due to pivoting, but the benefits in
*>  terms of accuracy have prevailed. The implementer/user can incorporate
*>  this extra QRF step easily. The implementer can also improve data movement
*>  (matrix transpose, matrix copy, matrix transposed copy) - this
*>  implementation of DGEJSV uses only the simplest, naive data movement.
*> \endverbatim
*
*> \par Contributors:
*  ==================
*>
*>  Zlatko Drmac (Zagreb, Croatia) and Kresimir Veselic (Hagen, Germany)
*
*> \par References:
*  ================
*>
*> \verbatim
*>
*> [1] Z. Drmac and K. Veselic: New fast and accurate Jacobi SVD algorithm I.
*>     SIAM J. Matrix Anal. Appl. Vol. 35, No. 2 (2008), pp. 1322-1342.
*>     LAPACK Working note 169.
*> [2] Z. Drmac and K. Veselic: New fast and accurate Jacobi SVD algorithm II.
*>     SIAM J. Matrix Anal. Appl. Vol. 35, No. 2 (2008), pp. 1343-1362.
*>     LAPACK Working note 170.
*> [3] Z. Drmac and Z. Bujanovic: On the failure of rank-revealing QR
*>     factorization software - a case study.
*>     ACM Trans. Math. Softw. Vol. 35, No 2 (2008), pp. 1-28.
*>     LAPACK Working note 176.
*> [4] Z. Drmac: SIGMA - mathematical software library for accurate SVD, PSV,
*>     QSVD, (H,K)-SVD computations.
*>     Department of Mathematics, University of Zagreb, 2008.
*> \endverbatim
*
*>  \par Bugs, examples and comments:
*   =================================
*>
*>  Please report all bugs and send interesting examples and/or comments to
*>  drmac@math.hr. Thank you.
*>
*  =====================================================================
      SUBROUTINE DGEJSV( JOBA, JOBU, JOBV, JOBR, JOBT, JOBP,
     $                   M, N, A, LDA, SVA, U, LDU, V, LDV,
     $                   WORK, LWORK, IWORK, INFO )
*
*  -- LAPACK computational routine (version 3.7.1) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     June 2016
*
*     .. Scalar Arguments ..
      IMPLICIT    NONE
      INTEGER     INFO, LDA, LDU, LDV, LWORK, M, N
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION A( LDA, * ), SVA( N ), U( LDU, * ), V( LDV, * ),
     $            WORK( LWORK )
      INTEGER     IWORK( * )
      CHARACTER*1 JOBA, JOBP, JOBR, JOBT, JOBU, JOBV
*     ..
*
*  ===========================================================================
*
*     .. Local Parameters ..
      DOUBLE PRECISION   ZERO,  ONE
      PARAMETER ( ZERO = 0.0D0, ONE = 1.0D0 )
*     ..
*     .. Local Scalars ..
      DOUBLE PRECISION AAPP, AAQQ, AATMAX, AATMIN, BIG, BIG1, COND_OK,
     $        CONDR1, CONDR2, ENTRA,  ENTRAT, EPSLN,  MAXPRJ, SCALEM,
     $        SCONDA, SFMIN,  SMALL,  TEMP1,  USCAL1, USCAL2, XSC
      INTEGER IERR,   N1,     NR,     NUMRANK,        p, q,   WARNING
      LOGICAL ALMORT, DEFR,   ERREST, GOSCAL, JRACC,  KILL,   LSVEC,
     $        L2ABER, L2KILL, L2PERT, L2RANK, L2TRAN,
     $        NOSCAL, ROWPIV, RSVEC,  TRANSP
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC DABS, DLOG, MAX, MIN, DBLE, IDNINT, DSIGN, DSQRT
*     ..
*     .. External Functions ..
      DOUBLE PRECISION  DLAMCH, DNRM2
      INTEGER   IDAMAX
      LOGICAL   LSAME
      EXTERNAL  IDAMAX, LSAME, DLAMCH, DNRM2
*     ..
*     .. External Subroutines ..
      EXTERNAL  DCOPY,  DGELQF, DGEQP3, DGEQRF, DLACPY, DLASCL,
     $          DLASET, DLASSQ, DLASWP, DORGQR, DORMLQ,
     $          DORMQR, DPOCON, DSCAL,  DSWAP,  DTRSM,  XERBLA
*
      EXTERNAL  DGESVJ
*     ..
*
*     Test the input arguments
*
      LSVEC  = LSAME( JOBU, 'U' ) .OR. LSAME( JOBU, 'F' )
      JRACC  = LSAME( JOBV, 'J' )
      RSVEC  = LSAME( JOBV, 'V' ) .OR. JRACC
      ROWPIV = LSAME( JOBA, 'F' ) .OR. LSAME( JOBA, 'G' )
      L2RANK = LSAME( JOBA, 'R' )
      L2ABER = LSAME( JOBA, 'A' )
      ERREST = LSAME( JOBA, 'E' ) .OR. LSAME( JOBA, 'G' )
      L2TRAN = LSAME( JOBT, 'T' )
      L2KILL = LSAME( JOBR, 'R' )
      DEFR   = LSAME( JOBR, 'N' )
      L2PERT = LSAME( JOBP, 'P' )
*
      IF ( .NOT.(ROWPIV .OR. L2RANK .OR. L2ABER .OR.
     $     ERREST .OR. LSAME( JOBA, 'C' ) )) THEN
         INFO = - 1
      ELSE IF ( .NOT.( LSVEC  .OR. LSAME( JOBU, 'N' ) .OR.
     $                             LSAME( JOBU, 'W' )) ) THEN
         INFO = - 2
      ELSE IF ( .NOT.( RSVEC .OR. LSAME( JOBV, 'N' ) .OR.
     $   LSAME( JOBV, 'W' )) .OR. ( JRACC .AND. (.NOT.LSVEC) ) ) THEN
         INFO = - 3
      ELSE IF ( .NOT. ( L2KILL .OR. DEFR ) )    THEN
         INFO = - 4
      ELSE IF ( .NOT. ( L2TRAN .OR. LSAME( JOBT, 'N' ) ) ) THEN
         INFO = - 5
      ELSE IF ( .NOT. ( L2PERT .OR. LSAME( JOBP, 'N' ) ) ) THEN
         INFO = - 6
      ELSE IF ( M .LT. 0 ) THEN
         INFO = - 7
      ELSE IF ( ( N .LT. 0 ) .OR. ( N .GT. M ) ) THEN
         INFO = - 8
      ELSE IF ( LDA .LT. M ) THEN
         INFO = - 10
      ELSE IF ( LSVEC .AND. ( LDU .LT. M ) ) THEN
         INFO = - 13
      ELSE IF ( RSVEC .AND. ( LDV .LT. N ) ) THEN
         INFO = - 15
      ELSE IF ( (.NOT.(LSVEC .OR. RSVEC .OR. ERREST).AND.
     &                           (LWORK .LT. MAX(7,4*N+1,2*M+N))) .OR.
     & (.NOT.(LSVEC .OR. RSVEC) .AND. ERREST .AND.
     &                         (LWORK .LT. MAX(7,4*N+N*N,2*M+N))) .OR.
     & (LSVEC .AND. (.NOT.RSVEC) .AND. (LWORK .LT. MAX(7,2*M+N,4*N+1)))
     & .OR.
     & (RSVEC .AND. (.NOT.LSVEC) .AND. (LWORK .LT. MAX(7,2*M+N,4*N+1)))
     & .OR.
     & (LSVEC .AND. RSVEC .AND. (.NOT.JRACC) .AND.
     &                          (LWORK.LT.MAX(2*M+N,6*N+2*N*N)))
     & .OR. (LSVEC .AND. RSVEC .AND. JRACC .AND.
     &                          LWORK.LT.MAX(2*M+N,4*N+N*N,2*N+N*N+6)))
     &   THEN
         INFO = - 17
      ELSE
*        #:)
         INFO = 0
      END IF
*
      IF ( INFO .NE. 0 ) THEN
*       #:(
         CALL XERBLA( 'DGEJSV', - INFO )
         RETURN
      END IF
*
*     Quick return for void matrix (Y3K safe)
* #:)
      IF ( ( M .EQ. 0 ) .OR. ( N .EQ. 0 ) ) THEN
         IWORK(1:3) = 0
         WORK(1:7) = 0
         RETURN
      ENDIF
*
*     Determine whether the matrix U should be M x N or M x M
*
      IF ( LSVEC ) THEN
         N1 = N
         IF ( LSAME( JOBU, 'F' ) ) N1 = M
      END IF
*
*     Set numerical parameters
*
*!    NOTE: Make sure DLAMCH() does not fail on the target architecture.
*
      EPSLN = DLAMCH('Epsilon')
      SFMIN = DLAMCH('SafeMinimum')
      SMALL = SFMIN / EPSLN
      BIG   = DLAMCH('O')
*     BIG   = ONE / SFMIN
*
*     Initialize SVA(1:N) = diag( ||A e_i||_2 )_1^N
*
*(!)  If necessary, scale SVA() to protect the largest norm from
*     overflow. It is possible that this scaling pushes the smallest
*     column norm left from the underflow threshold (extreme case).
*
      SCALEM  = ONE / DSQRT(DBLE(M)*DBLE(N))
      NOSCAL  = .TRUE.
      GOSCAL  = .TRUE.
      DO 1874 p = 1, N
         AAPP = ZERO
         AAQQ = ONE
         CALL DLASSQ( M, A(1,p), 1, AAPP, AAQQ )
         IF ( AAPP .GT. BIG ) THEN
            INFO = - 9
            CALL XERBLA( 'DGEJSV', -INFO )
            RETURN
         END IF
         AAQQ = DSQRT(AAQQ)
         IF ( ( AAPP .LT. (BIG / AAQQ) ) .AND. NOSCAL  ) THEN
            SVA(p)  = AAPP * AAQQ
         ELSE
            NOSCAL  = .FALSE.
            SVA(p)  = AAPP * ( AAQQ * SCALEM )
            IF ( GOSCAL ) THEN
               GOSCAL = .FALSE.
               CALL DSCAL( p-1, SCALEM, SVA, 1 )
            END IF
         END IF
 1874 CONTINUE
*
      IF ( NOSCAL ) SCALEM = ONE
*
      AAPP = ZERO
      AAQQ = BIG
      DO 4781 p = 1, N
         AAPP = MAX( AAPP, SVA(p) )
         IF ( SVA(p) .NE. ZERO ) AAQQ = MIN( AAQQ, SVA(p) )
 4781 CONTINUE
*
*     Quick return for zero M x N matrix
* #:)
      IF ( AAPP .EQ. ZERO ) THEN
         IF ( LSVEC ) CALL DLASET( 'G', M, N1, ZERO, ONE, U, LDU )
         IF ( RSVEC ) CALL DLASET( 'G', N, N,  ZERO, ONE, V, LDV )
         WORK(1) = ONE
         WORK(2) = ONE
         IF ( ERREST ) WORK(3) = ONE
         IF ( LSVEC .AND. RSVEC ) THEN
            WORK(4) = ONE
            WORK(5) = ONE
         END IF
         IF ( L2TRAN ) THEN
            WORK(6) = ZERO
            WORK(7) = ZERO
         END IF
         IWORK(1) = 0
         IWORK(2) = 0
         IWORK(3) = 0
         RETURN
      END IF
*
*     Issue warning if denormalized column norms detected. Override the
*     high relative accuracy request. Issue licence to kill columns
*     (set them to zero) whose norm is less than sigma_max / BIG (roughly).
* #:(
      WARNING = 0
      IF ( AAQQ .LE. SFMIN ) THEN
         L2RANK = .TRUE.
         L2KILL = .TRUE.
         WARNING = 1
      END IF
*
*     Quick return for one-column matrix
* #:)
      IF ( N .EQ. 1 ) THEN
*
         IF ( LSVEC ) THEN
            CALL DLASCL( 'G',0,0,SVA(1),SCALEM, M,1,A(1,1),LDA,IERR )
            CALL DLACPY( 'A', M, 1, A, LDA, U, LDU )
*           computing all M left singular vectors of the M x 1 matrix
            IF ( N1 .NE. N  ) THEN
               CALL DGEQRF( M, N, U,LDU, WORK, WORK(N+1),LWORK-N,IERR )
               CALL DORGQR( M,N1,1, U,LDU,WORK,WORK(N+1),LWORK-N,IERR )
               CALL DCOPY( M, A(1,1), 1, U(1,1), 1 )
            END IF
         END IF
         IF ( RSVEC ) THEN
             V(1,1) = ONE
         END IF
         IF ( SVA(1) .LT. (BIG*SCALEM) ) THEN
            SVA(1)  = SVA(1) / SCALEM
            SCALEM  = ONE
         END IF
         WORK(1) = ONE / SCALEM
         WORK(2) = ONE
         IF ( SVA(1) .NE. ZERO ) THEN
            IWORK(1) = 1
            IF ( ( SVA(1) / SCALEM) .GE. SFMIN ) THEN
               IWORK(2) = 1
            ELSE
               IWORK(2) = 0
            END IF
         ELSE
            IWORK(1) = 0
            IWORK(2) = 0
         END IF
         IWORK(3) = 0
         IF ( ERREST ) WORK(3) = ONE
         IF ( LSVEC .AND. RSVEC ) THEN
            WORK(4) = ONE
            WORK(5) = ONE
         END IF
         IF ( L2TRAN ) THEN
            WORK(6) = ZERO
            WORK(7) = ZERO
         END IF
         RETURN
*
      END IF
*
      TRANSP = .FALSE.
      L2TRAN = L2TRAN .AND. ( M .EQ. N )
*
      AATMAX = -ONE
      AATMIN =  BIG
      IF ( ROWPIV .OR. L2TRAN ) THEN
*
*     Compute the row norms, needed to determine row pivoting sequence
*     (in the case of heavily row weighted A, row pivoting is strongly
*     advised) and to collect information needed to compare the
*     structures of A * A^t and A^t * A (in the case L2TRAN.EQ..TRUE.).
*
         IF ( L2TRAN ) THEN
            DO 1950 p = 1, M
               XSC   = ZERO
               TEMP1 = ONE
               CALL DLASSQ( N, A(p,1), LDA, XSC, TEMP1 )
*              DLASSQ gets both the ell_2 and the ell_infinity norm
*              in one pass through the vector
               WORK(M+N+p)  = XSC * SCALEM
               WORK(N+p)    = XSC * (SCALEM*DSQRT(TEMP1))
               AATMAX = MAX( AATMAX, WORK(N+p) )
               IF (WORK(N+p) .NE. ZERO) AATMIN = MIN(AATMIN,WORK(N+p))
 1950       CONTINUE
         ELSE
            DO 1904 p = 1, M
               WORK(M+N+p) = SCALEM*DABS( A(p,IDAMAX(N,A(p,1),LDA)) )
               AATMAX = MAX( AATMAX, WORK(M+N+p) )
               AATMIN = MIN( AATMIN, WORK(M+N+p) )
 1904       CONTINUE
         END IF
*
      END IF
*
*     For square matrix A try to determine whether A^t  would be  better
*     input for the preconditioned Jacobi SVD, with faster convergence.
*     The decision is based on an O(N) function of the vector of column
*     and row norms of A, based on the Shannon entropy. This should give
*     the right choice in most cases when the difference actually matters.
*     It may fail and pick the slower converging side.
*
      ENTRA  = ZERO
      ENTRAT = ZERO
      IF ( L2TRAN ) THEN
*
         XSC   = ZERO
         TEMP1 = ONE
         CALL DLASSQ( N, SVA, 1, XSC, TEMP1 )
         TEMP1 = ONE / TEMP1
*
         ENTRA = ZERO
         DO 1113 p = 1, N
            BIG1  = ( ( SVA(p) / XSC )**2 ) * TEMP1
            IF ( BIG1 .NE. ZERO ) ENTRA = ENTRA + BIG1 * DLOG(BIG1)
 1113    CONTINUE
         ENTRA = - ENTRA / DLOG(DBLE(N))
*
*        Now, SVA().^2/Trace(A^t * A) is a point in the probability simplex.
*        It is derived from the diagonal of  A^t * A.  Do the same with the
*        diagonal of A * A^t, compute the entropy of the corresponding
*        probability distribution. Note that A * A^t and A^t * A have the
*        same trace.
*
         ENTRAT = ZERO
         DO 1114 p = N+1, N+M
            BIG1 = ( ( WORK(p) / XSC )**2 ) * TEMP1
            IF ( BIG1 .NE. ZERO ) ENTRAT = ENTRAT + BIG1 * DLOG(BIG1)
 1114    CONTINUE
         ENTRAT = - ENTRAT / DLOG(DBLE(M))
*
*        Analyze the entropies and decide A or A^t. Smaller entropy
*        usually means better input for the algorithm.
*
         TRANSP = ( ENTRAT .LT. ENTRA )
*
*        If A^t is better than A, transpose A.
*
         IF ( TRANSP ) THEN
*           In an optimal implementation, this trivial transpose
*           should be replaced with faster transpose.
            DO 1115 p = 1, N - 1
               DO 1116 q = p + 1, N
                   TEMP1 = A(q,p)
                  A(q,p) = A(p,q)
                  A(p,q) = TEMP1
 1116          CONTINUE
 1115       CONTINUE
            DO 1117 p = 1, N
               WORK(M+N+p) = SVA(p)
               SVA(p)      = WORK(N+p)
 1117       CONTINUE
            TEMP1  = AAPP
            AAPP   = AATMAX
            AATMAX = TEMP1
            TEMP1  = AAQQ
            AAQQ   = AATMIN
            AATMIN = TEMP1
            KILL   = LSVEC
            LSVEC  = RSVEC
            RSVEC  = KILL
            IF ( LSVEC ) N1 = N
*
            ROWPIV = .TRUE.
         END IF
*
      END IF
*     END IF L2TRAN
*
*     Scale the matrix so that its maximal singular value remains less
*     than DSQRT(BIG) -- the matrix is scaled so that its maximal column
*     has Euclidean norm equal to DSQRT(BIG/N). The only reason to keep
*     DSQRT(BIG) instead of BIG is the fact that DGEJSV uses LAPACK and
*     BLAS routines that, in some implementations, are not capable of
*     working in the full interval [SFMIN,BIG] and that they may provoke
*     overflows in the intermediate results. If the singular values spread
*     from SFMIN to BIG, then DGESVJ will compute them. So, in that case,
*     one should use DGESVJ instead of DGEJSV.
*
      BIG1   = DSQRT( BIG )
      TEMP1  = DSQRT( BIG / DBLE(N) )
*
      CALL DLASCL( 'G', 0, 0, AAPP, TEMP1, N, 1, SVA, N, IERR )
      IF ( AAQQ .GT. (AAPP * SFMIN) ) THEN
          AAQQ = ( AAQQ / AAPP ) * TEMP1
      ELSE
          AAQQ = ( AAQQ * TEMP1 ) / AAPP
      END IF
      TEMP1 = TEMP1 * SCALEM
      CALL DLASCL( 'G', 0, 0, AAPP, TEMP1, M, N, A, LDA, IERR )
*
*     To undo scaling at the end of this procedure, multiply the
*     computed singular values with USCAL2 / USCAL1.
*
      USCAL1 = TEMP1
      USCAL2 = AAPP
*
      IF ( L2KILL ) THEN
*        L2KILL enforces computation of nonzero singular values in
*        the restricted range of condition number of the initial A,
*        sigma_max(A) / sigma_min(A) approx. DSQRT(BIG)/DSQRT(SFMIN).
         XSC = DSQRT( SFMIN )
      ELSE
         XSC = SMALL
*
*        Now, if the condition number of A is too big,
*        sigma_max(A) / sigma_min(A) .GT. DSQRT(BIG/N) * EPSLN / SFMIN,
*        as a precaution measure, the full SVD is computed using DGESVJ
*        with accumulated Jacobi rotations. This provides numerically
*        more robust computation, at the cost of slightly increased run
*        time. Depending on the concrete implementation of BLAS and LAPACK
*        (i.e. how they behave in presence of extreme ill-conditioning) the
*        implementor may decide to remove this switch.
         IF ( ( AAQQ.LT.DSQRT(SFMIN) ) .AND. LSVEC .AND. RSVEC ) THEN
            JRACC = .TRUE.
         END IF
*
      END IF
      IF ( AAQQ .LT. XSC ) THEN
         DO 700 p = 1, N
            IF ( SVA(p) .LT. XSC ) THEN
               CALL DLASET( 'A', M, 1, ZERO, ZERO, A(1,p), LDA )
               SVA(p) = ZERO
            END IF
 700     CONTINUE
      END IF
*
*     Preconditioning using QR factorization with pivoting
*
      IF ( ROWPIV ) THEN
*        Optional row permutation (Bjoerck row pivoting):
*        A result by Cox and Higham shows that the Bjoerck's
*        row pivoting combined with standard column pivoting
*        has similar effect as Powell-Reid complete pivoting.
*        The ell-infinity norms of A are made nonincreasing.
         DO 1952 p = 1, M - 1
            q = IDAMAX( M-p+1, WORK(M+N+p), 1 ) + p - 1
            IWORK(2*N+p) = q
            IF ( p .NE. q ) THEN
               TEMP1       = WORK(M+N+p)
               WORK(M+N+p) = WORK(M+N+q)
               WORK(M+N+q) = TEMP1
            END IF
 1952    CONTINUE
         CALL DLASWP( N, A, LDA, 1, M-1, IWORK(2*N+1), 1 )
      END IF
*
*     End of the preparation phase (scaling, optional sorting and
*     transposing, optional flushing of small columns).
*
*     Preconditioning
*
*     If the full SVD is needed, the right singular vectors are computed
*     from a matrix equation, and for that we need theoretical analysis
*     of the Businger-Golub pivoting. So we use DGEQP3 as the first RR QRF.
*     In all other cases the first RR QRF can be chosen by other criteria
*     (eg speed by replacing global with restricted window pivoting, such
*     as in SGEQPX from TOMS # 782). Good results will be obtained using
*     SGEQPX with properly (!) chosen numerical parameters.
*     Any improvement of DGEQP3 improves overal performance of DGEJSV.
*
*     A * P1 = Q1 * [ R1^t 0]^t:
      DO 1963 p = 1, N
*        .. all columns are free columns
         IWORK(p) = 0
 1963 CONTINUE
      CALL DGEQP3( M,N,A,LDA, IWORK,WORK, WORK(N+1),LWORK-N, IERR )
*
*     The upper triangular matrix R1 from the first QRF is inspected for
*     rank deficiency and possibilities for deflation, or possible
*     ill-conditioning. Depending on the user specified flag L2RANK,
*     the procedure explores possibilities to reduce the numerical
*     rank by inspecting the computed upper triangular factor. If
*     L2RANK or L2ABER are up, then DGEJSV will compute the SVD of
*     A + dA, where ||dA|| <= f(M,N)*EPSLN.
*
      NR = 1
      IF ( L2ABER ) THEN
*        Standard absolute error bound suffices. All sigma_i with
*        sigma_i < N*EPSLN*||A|| are flushed to zero. This is an
*        agressive enforcement of lower numerical rank by introducing a
*        backward error of the order of N*EPSLN*||A||.
         TEMP1 = DSQRT(DBLE(N))*EPSLN
         DO 3001 p = 2, N
            IF ( DABS(A(p,p)) .GE. (TEMP1*DABS(A(1,1))) ) THEN
               NR = NR + 1
            ELSE
               GO TO 3002
            END IF
 3001    CONTINUE
 3002    CONTINUE
      ELSE IF ( L2RANK ) THEN
*        .. similarly as above, only slightly more gentle (less agressive).
*        Sudden drop on the diagonal of R1 is used as the criterion for
*        close-to-rank-deficient.
         TEMP1 = DSQRT(SFMIN)
         DO 3401 p = 2, N
            IF ( ( DABS(A(p,p)) .LT. (EPSLN*DABS(A(p-1,p-1))) ) .OR.
     $           ( DABS(A(p,p)) .LT. SMALL ) .OR.
     $           ( L2KILL .AND. (DABS(A(p,p)) .LT. TEMP1) ) ) GO TO 3402
            NR = NR + 1
 3401    CONTINUE
 3402    CONTINUE
*
      ELSE
*        The goal is high relative accuracy. However, if the matrix
*        has high scaled condition number the relative accuracy is in
*        general not feasible. Later on, a condition number estimator
*        will be deployed to estimate the scaled condition number.
*        Here we just remove the underflowed part of the triangular
*        factor. This prevents the situation in which the code is
*        working hard to get the accuracy not warranted by the data.
         TEMP1  = DSQRT(SFMIN)
         DO 3301 p = 2, N
            IF ( ( DABS(A(p,p)) .LT. SMALL ) .OR.
     $          ( L2KILL .AND. (DABS(A(p,p)) .LT. TEMP1) ) ) GO TO 3302
            NR = NR + 1
 3301    CONTINUE
 3302    CONTINUE
*
      END IF
*
      ALMORT = .FALSE.
      IF ( NR .EQ. N ) THEN
         MAXPRJ = ONE
         DO 3051 p = 2, N
            TEMP1  = DABS(A(p,p)) / SVA(IWORK(p))
            MAXPRJ = MIN( MAXPRJ, TEMP1 )
 3051    CONTINUE
         IF ( MAXPRJ**2 .GE. ONE - DBLE(N)*EPSLN ) ALMORT = .TRUE.
      END IF
*
*
      SCONDA = - ONE
      CONDR1 = - ONE
      CONDR2 = - ONE
*
      IF ( ERREST ) THEN
         IF ( N .EQ. NR ) THEN
            IF ( RSVEC ) THEN
*              .. V is available as workspace
               CALL DLACPY( 'U', N, N, A, LDA, V, LDV )
               DO 3053 p = 1, N
                  TEMP1 = SVA(IWORK(p))
                  CALL DSCAL( p, ONE/TEMP1, V(1,p), 1 )
 3053          CONTINUE
               CALL DPOCON( 'U', N, V, LDV, ONE, TEMP1,
     $              WORK(N+1), IWORK(2*N+M+1), IERR )
            ELSE IF ( LSVEC ) THEN
*              .. U is available as workspace
               CALL DLACPY( 'U', N, N, A, LDA, U, LDU )
               DO 3054 p = 1, N
                  TEMP1 = SVA(IWORK(p))
                  CALL DSCAL( p, ONE/TEMP1, U(1,p), 1 )
 3054          CONTINUE
               CALL DPOCON( 'U', N, U, LDU, ONE, TEMP1,
     $              WORK(N+1), IWORK(2*N+M+1), IERR )
            ELSE
               CALL DLACPY( 'U', N, N, A, LDA, WORK(N+1), N )
               DO 3052 p = 1, N
                  TEMP1 = SVA(IWORK(p))
                  CALL DSCAL( p, ONE/TEMP1, WORK(N+(p-1)*N+1), 1 )
 3052          CONTINUE
*           .. the columns of R are scaled to have unit Euclidean lengths.
               CALL DPOCON( 'U', N, WORK(N+1), N, ONE, TEMP1,
     $              WORK(N+N*N+1), IWORK(2*N+M+1), IERR )
            END IF
            SCONDA = ONE / DSQRT(TEMP1)
*           SCONDA is an estimate of DSQRT(||(R^t * R)^(-1)||_1).
*           N^(-1/4) * SCONDA <= ||R^(-1)||_2 <= N^(1/4) * SCONDA
         ELSE
            SCONDA = - ONE
         END IF
      END IF
*
      L2PERT = L2PERT .AND. ( DABS( A(1,1)/A(NR,NR) ) .GT. DSQRT(BIG1) )
*     If there is no violent scaling, artificial perturbation is not needed.
*
*     Phase 3:
*
      IF ( .NOT. ( RSVEC .OR. LSVEC ) ) THEN
*
*         Singular Values only
*
*         .. transpose A(1:NR,1:N)
         DO 1946 p = 1, MIN( N-1, NR )
            CALL DCOPY( N-p, A(p,p+1), LDA, A(p+1,p), 1 )
 1946    CONTINUE
*
*        The following two DO-loops introduce small relative perturbation
*        into the strict upper triangle of the lower triangular matrix.
*        Small entries below the main diagonal are also changed.
*        This modification is useful if the computing environment does not
*        provide/allow FLUSH TO ZERO underflow, for it prevents many
*        annoying denormalized numbers in case of strongly scaled matrices.
*        The perturbation is structured so that it does not introduce any
*        new perturbation of the singular values, and it does not destroy
*        the job done by the preconditioner.
*        The licence for this perturbation is in the variable L2PERT, which
*        should be .FALSE. if FLUSH TO ZERO underflow is active.
*
         IF ( .NOT. ALMORT ) THEN
*
            IF ( L2PERT ) THEN
*              XSC = DSQRT(SMALL)
               XSC = EPSLN / DBLE(N)
               DO 4947 q = 1, NR
                  TEMP1 = XSC*DABS(A(q,q))
                  DO 4949 p = 1, N
                     IF ( ( (p.GT.q) .AND. (DABS(A(p,q)).LE.TEMP1) )
     $                    .OR. ( p .LT. q ) )
     $                     A(p,q) = DSIGN( TEMP1, A(p,q) )
 4949             CONTINUE
 4947          CONTINUE
            ELSE
               CALL DLASET( 'U', NR-1,NR-1, ZERO,ZERO, A(1,2),LDA )
            END IF
*
*            .. second preconditioning using the QR factorization
*
            CALL DGEQRF( N,NR, A,LDA, WORK, WORK(N+1),LWORK-N, IERR )
*
*           .. and transpose upper to lower triangular
            DO 1948 p = 1, NR - 1
               CALL DCOPY( NR-p, A(p,p+1), LDA, A(p+1,p), 1 )
 1948       CONTINUE
*
         END IF
*
*           Row-cyclic Jacobi SVD algorithm with column pivoting
*
*           .. again some perturbation (a "background noise") is added
*           to drown denormals
            IF ( L2PERT ) THEN
*              XSC = DSQRT(SMALL)
               XSC = EPSLN / DBLE(N)
               DO 1947 q = 1, NR
                  TEMP1 = XSC*DABS(A(q,q))
                  DO 1949 p = 1, NR
                     IF ( ( (p.GT.q) .AND. (DABS(A(p,q)).LE.TEMP1) )
     $                       .OR. ( p .LT. q ) )
     $                   A(p,q) = DSIGN( TEMP1, A(p,q) )
 1949             CONTINUE
 1947          CONTINUE
            ELSE
               CALL DLASET( 'U', NR-1, NR-1, ZERO, ZERO, A(1,2), LDA )
            END IF
*
*           .. and one-sided Jacobi rotations are started on a lower
*           triangular matrix (plus perturbation which is ignored in
*           the part which destroys triangular form (confusing?!))
*
            CALL DGESVJ( 'L', 'NoU', 'NoV', NR, NR, A, LDA, SVA,
     $                      N, V, LDV, WORK, LWORK, INFO )
*
            SCALEM  = WORK(1)
            NUMRANK = IDNINT(WORK(2))
*
*
      ELSE IF ( RSVEC .AND. ( .NOT. LSVEC ) ) THEN
*
*        -> Singular Values and Right Singular Vectors <-
*
         IF ( ALMORT ) THEN
*
*           .. in this case NR equals N
            DO 1998 p = 1, NR
               CALL DCOPY( N-p+1, A(p,p), LDA, V(p,p), 1 )
 1998       CONTINUE
            CALL DLASET( 'Upper', NR-1, NR-1, ZERO, ZERO, V(1,2), LDV )
*
            CALL DGESVJ( 'L','U','N', N, NR, V,LDV, SVA, NR, A,LDA,
     $                  WORK, LWORK, INFO )
            SCALEM  = WORK(1)
            NUMRANK = IDNINT(WORK(2))

         ELSE
*
*        .. two more QR factorizations ( one QRF is not enough, two require
*        accumulated product of Jacobi rotations, three are perfect )
*
            CALL DLASET( 'Lower', NR-1, NR-1, ZERO, ZERO, A(2,1), LDA )
            CALL DGELQF( NR, N, A, LDA, WORK, WORK(N+1), LWORK-N, IERR)
            CALL DLACPY( 'Lower', NR, NR, A, LDA, V, LDV )
            CALL DLASET( 'Upper', NR-1, NR-1, ZERO, ZERO, V(1,2), LDV )
            CALL DGEQRF( NR, NR, V, LDV, WORK(N+1), WORK(2*N+1),
     $                   LWORK-2*N, IERR )
            DO 8998 p = 1, NR
               CALL DCOPY( NR-p+1, V(p,p), LDV, V(p,p), 1 )
 8998       CONTINUE
            CALL DLASET( 'Upper', NR-1, NR-1, ZERO, ZERO, V(1,2), LDV )
*
            CALL DGESVJ( 'Lower', 'U','N', NR, NR, V,LDV, SVA, NR, U,
     $                  LDU, WORK(N+1), LWORK, INFO )
            SCALEM  = WORK(N+1)
            NUMRANK = IDNINT(WORK(N+2))
            IF ( NR .LT. N ) THEN
               CALL DLASET( 'A',N-NR, NR, ZERO,ZERO, V(NR+1,1),   LDV )
               CALL DLASET( 'A',NR, N-NR, ZERO,ZERO, V(1,NR+1),   LDV )
               CALL DLASET( 'A',N-NR,N-NR,ZERO,ONE, V(NR+1,NR+1), LDV )
            END IF
*
         CALL DORMLQ( 'Left', 'Transpose', N, N, NR, A, LDA, WORK,
     $               V, LDV, WORK(N+1), LWORK-N, IERR )
*
         END IF
*
         DO 8991 p = 1, N
            CALL DCOPY( N, V(p,1), LDV, A(IWORK(p),1), LDA )
 8991    CONTINUE
         CALL DLACPY( 'All', N, N, A, LDA, V, LDV )
*
         IF ( TRANSP ) THEN
            CALL DLACPY( 'All', N, N, V, LDV, U, LDU )
         END IF
*
      ELSE IF ( LSVEC .AND. ( .NOT. RSVEC ) ) THEN
*
*        .. Singular Values and Left Singular Vectors                 ..
*
*        .. second preconditioning step to avoid need to accumulate
*        Jacobi rotations in the Jacobi iterations.
         DO 1965 p = 1, NR
            CALL DCOPY( N-p+1, A(p,p), LDA, U(p,p), 1 )
 1965    CONTINUE
         CALL DLASET( 'Upper', NR-1, NR-1, ZERO, ZERO, U(1,2), LDU )
*
         CALL DGEQRF( N, NR, U, LDU, WORK(N+1), WORK(2*N+1),
     $              LWORK-2*N, IERR )
*
         DO 1967 p = 1, NR - 1
            CALL DCOPY( NR-p, U(p,p+1), LDU, U(p+1,p), 1 )
 1967    CONTINUE
         CALL DLASET( 'Upper', NR-1, NR-1, ZERO, ZERO, U(1,2), LDU )
*
         CALL DGESVJ( 'Lower', 'U', 'N', NR,NR, U, LDU, SVA, NR, A,
     $        LDA, WORK(N+1), LWORK-N, INFO )
         SCALEM  = WORK(N+1)
         NUMRANK = IDNINT(WORK(N+2))
*
         IF ( NR .LT. M ) THEN
            CALL DLASET( 'A',  M-NR, NR,ZERO, ZERO, U(NR+1,1), LDU )
            IF ( NR .LT. N1 ) THEN
               CALL DLASET( 'A',NR, N1-NR, ZERO, ZERO, U(1,NR+1), LDU )
               CALL DLASET( 'A',M-NR,N1-NR,ZERO,ONE,U(NR+1,NR+1), LDU )
            END IF
         END IF
*
         CALL DORMQR( 'Left', 'No Tr', M, N1, N, A, LDA, WORK, U,
     $               LDU, WORK(N+1), LWORK-N, IERR )
*
         IF ( ROWPIV )
     $       CALL DLASWP( N1, U, LDU, 1, M-1, IWORK(2*N+1), -1 )
*
         DO 1974 p = 1, N1
            XSC = ONE / DNRM2( M, U(1,p), 1 )
            CALL DSCAL( M, XSC, U(1,p), 1 )
 1974    CONTINUE
*
         IF ( TRANSP ) THEN
            CALL DLACPY( 'All', N, N, U, LDU, V, LDV )
         END IF
*
      ELSE
*
*        .. Full SVD ..
*
         IF ( .NOT. JRACC ) THEN
*
         IF ( .NOT. ALMORT ) THEN
*
*           Second Preconditioning Step (QRF [with pivoting])
*           Note that the composition of TRANSPOSE, QRF and TRANSPOSE is
*           equivalent to an LQF CALL. Since in many libraries the QRF
*           seems to be better optimized than the LQF, we do explicit
*           transpose and use the QRF. This is subject to changes in an
*           optimized implementation of DGEJSV.
*
            DO 1968 p = 1, NR
               CALL DCOPY( N-p+1, A(p,p), LDA, V(p,p), 1 )
 1968       CONTINUE
*
*           .. the following two loops perturb small entries to avoid
*           denormals in the second QR factorization, where they are
*           as good as zeros. This is done to avoid painfully slow
*           computation with denormals. The relative size of the perturbation
*           is a parameter that can be changed by the implementer.
*           This perturbation device will be obsolete on machines with
*           properly implemented arithmetic.
*           To switch it off, set L2PERT=.FALSE. To remove it from  the
*           code, remove the action under L2PERT=.TRUE., leave the ELSE part.
*           The following two loops should be blocked and fused with the
*           transposed copy above.
*
            IF ( L2PERT ) THEN
               XSC = DSQRT(SMALL)
               DO 2969 q = 1, NR
                  TEMP1 = XSC*DABS( V(q,q) )
                  DO 2968 p = 1, N
                     IF ( ( p .GT. q ) .AND. ( DABS(V(p,q)) .LE. TEMP1 )
     $                   .OR. ( p .LT. q ) )
     $                   V(p,q) = DSIGN( TEMP1, V(p,q) )
                     IF ( p .LT. q ) V(p,q) = - V(p,q)
 2968             CONTINUE
 2969          CONTINUE
            ELSE
               CALL DLASET( 'U', NR-1, NR-1, ZERO, ZERO, V(1,2), LDV )
            END IF
*
*           Estimate the row scaled condition number of R1
*           (If R1 is rectangular, N > NR, then the condition number
*           of the leading NR x NR submatrix is estimated.)
*
            CALL DLACPY( 'L', NR, NR, V, LDV, WORK(2*N+1), NR )
            DO 3950 p = 1, NR
               TEMP1 = DNRM2(NR-p+1,WORK(2*N+(p-1)*NR+p),1)
               CALL DSCAL(NR-p+1,ONE/TEMP1,WORK(2*N+(p-1)*NR+p),1)
 3950       CONTINUE
            CALL DPOCON('Lower',NR,WORK(2*N+1),NR,ONE,TEMP1,
     $                   WORK(2*N+NR*NR+1),IWORK(M+2*N+1),IERR)
            CONDR1 = ONE / DSQRT(TEMP1)
*           .. here need a second oppinion on the condition number
*           .. then assume worst case scenario
*           R1 is OK for inverse <=> CONDR1 .LT. DBLE(N)
*           more conservative    <=> CONDR1 .LT. DSQRT(DBLE(N))
*
            COND_OK = DSQRT(DBLE(NR))
*[TP]       COND_OK is a tuning parameter.

            IF ( CONDR1 .LT. COND_OK ) THEN
*              .. the second QRF without pivoting. Note: in an optimized
*              implementation, this QRF should be implemented as the QRF
*              of a lower triangular matrix.
*              R1^t = Q2 * R2
               CALL DGEQRF( N, NR, V, LDV, WORK(N+1), WORK(2*N+1),
     $              LWORK-2*N, IERR )
*
               IF ( L2PERT ) THEN
                  XSC = DSQRT(SMALL)/EPSLN
                  DO 3959 p = 2, NR
                     DO 3958 q = 1, p - 1
                        TEMP1 = XSC * MIN(DABS(V(p,p)),DABS(V(q,q)))
                        IF ( DABS(V(q,p)) .LE. TEMP1 )
     $                     V(q,p) = DSIGN( TEMP1, V(q,p) )
 3958                CONTINUE
 3959             CONTINUE
               END IF
*
               IF ( NR .NE. N )
     $         CALL DLACPY( 'A', N, NR, V, LDV, WORK(2*N+1), N )
*              .. save ...
*
*           .. this transposed copy should be better than naive
               DO 1969 p = 1, NR - 1
                  CALL DCOPY( NR-p, V(p,p+1), LDV, V(p+1,p), 1 )
 1969          CONTINUE
*
               CONDR2 = CONDR1
*
            ELSE
*
*              .. ill-conditioned case: second QRF with pivoting
*              Note that windowed pivoting would be equaly good
*              numerically, and more run-time efficient. So, in
*              an optimal implementation, the next call to DGEQP3
*              should be replaced with eg. CALL SGEQPX (ACM TOMS #782)
*              with properly (carefully) chosen parameters.
*
*              R1^t * P2 = Q2 * R2
               DO 3003 p = 1, NR
                  IWORK(N+p) = 0
 3003          CONTINUE
               CALL DGEQP3( N, NR, V, LDV, IWORK(N+1), WORK(N+1),
     $                  WORK(2*N+1), LWORK-2*N, IERR )
**               CALL DGEQRF( N, NR, V, LDV, WORK(N+1), WORK(2*N+1),
**     $              LWORK-2*N, IERR )
               IF ( L2PERT ) THEN
                  XSC = DSQRT(SMALL)
                  DO 3969 p = 2, NR
                     DO 3968 q = 1, p - 1
                        TEMP1 = XSC * MIN(DABS(V(p,p)),DABS(V(q,q)))
                        IF ( DABS(V(q,p)) .LE. TEMP1 )
     $                     V(q,p) = DSIGN( TEMP1, V(q,p) )
 3968                CONTINUE
 3969             CONTINUE
               END IF
*
               CALL DLACPY( 'A', N, NR, V, LDV, WORK(2*N+1), N )
*
               IF ( L2PERT ) THEN
                  XSC = DSQRT(SMALL)
                  DO 8970 p = 2, NR
                     DO 8971 q = 1, p - 1
                        TEMP1 = XSC * MIN(DABS(V(p,p)),DABS(V(q,q)))
                        V(p,q) = - DSIGN( TEMP1, V(q,p) )
 8971                CONTINUE
 8970             CONTINUE
               ELSE
                  CALL DLASET( 'L',NR-1,NR-1,ZERO,ZERO,V(2,1),LDV )
               END IF
*              Now, compute R2 = L3 * Q3, the LQ factorization.
               CALL DGELQF( NR, NR, V, LDV, WORK(2*N+N*NR+1),
     $               WORK(2*N+N*NR+NR+1), LWORK-2*N-N*NR-NR, IERR )
*              .. and estimate the condition number
               CALL DLACPY( 'L',NR,NR,V,LDV,WORK(2*N+N*NR+NR+1),NR )
               DO 4950 p = 1, NR
                  TEMP1 = DNRM2( p, WORK(2*N+N*NR+NR+p), NR )
                  CALL DSCAL( p, ONE/TEMP1, WORK(2*N+N*NR+NR+p), NR )
 4950          CONTINUE
               CALL DPOCON( 'L',NR,WORK(2*N+N*NR+NR+1),NR,ONE,TEMP1,
     $              WORK(2*N+N*NR+NR+NR*NR+1),IWORK(M+2*N+1),IERR )
               CONDR2 = ONE / DSQRT(TEMP1)
*
               IF ( CONDR2 .GE. COND_OK ) THEN
*                 .. save the Householder vectors used for Q3
*                 (this overwrittes the copy of R2, as it will not be
*                 needed in this branch, but it does not overwritte the
*                 Huseholder vectors of Q2.).
                  CALL DLACPY( 'U', NR, NR, V, LDV, WORK(2*N+1), N )
*                 .. and the rest of the information on Q3 is in
*                 WORK(2*N+N*NR+1:2*N+N*NR+N)
               END IF
*
            END IF
*
            IF ( L2PERT ) THEN
               XSC = DSQRT(SMALL)
               DO 4968 q = 2, NR
                  TEMP1 = XSC * V(q,q)
                  DO 4969 p = 1, q - 1
*                    V(p,q) = - DSIGN( TEMP1, V(q,p) )
                     V(p,q) = - DSIGN( TEMP1, V(p,q) )
 4969             CONTINUE
 4968          CONTINUE
            ELSE
               CALL DLASET( 'U', NR-1,NR-1, ZERO,ZERO, V(1,2), LDV )
            END IF
*
*        Second preconditioning finished; continue with Jacobi SVD
*        The input matrix is lower trinagular.
*
*        Recover the right singular vectors as solution of a well
*        conditioned triangular matrix equation.
*
            IF ( CONDR1 .LT. COND_OK ) THEN
*
               CALL DGESVJ( 'L','U','N',NR,NR,V,LDV,SVA,NR,U,
     $              LDU,WORK(2*N+N*NR+NR+1),LWORK-2*N-N*NR-NR,INFO )
               SCALEM  = WORK(2*N+N*NR+NR+1)
               NUMRANK = IDNINT(WORK(2*N+N*NR+NR+2))
               DO 3970 p = 1, NR
                  CALL DCOPY( NR, V(1,p), 1, U(1,p), 1 )
                  CALL DSCAL( NR, SVA(p),    V(1,p), 1 )
 3970          CONTINUE

*        .. pick the right matrix equation and solve it
*
               IF ( NR .EQ. N ) THEN
* :))             .. best case, R1 is inverted. The solution of this matrix
*                 equation is Q2*V2 = the product of the Jacobi rotations
*                 used in DGESVJ, premultiplied with the orthogonal matrix
*                 from the second QR factorization.
                  CALL DTRSM( 'L','U','N','N', NR,NR,ONE, A,LDA, V,LDV )
               ELSE
*                 .. R1 is well conditioned, but non-square. Transpose(R2)
*                 is inverted to get the product of the Jacobi rotations
*                 used in DGESVJ. The Q-factor from the second QR
*                 factorization is then built in explicitly.
                  CALL DTRSM('L','U','T','N',NR,NR,ONE,WORK(2*N+1),
     $                 N,V,LDV)
                  IF ( NR .LT. N ) THEN
                    CALL DLASET('A',N-NR,NR,ZERO,ZERO,V(NR+1,1),LDV)
                    CALL DLASET('A',NR,N-NR,ZERO,ZERO,V(1,NR+1),LDV)
                    CALL DLASET('A',N-NR,N-NR,ZERO,ONE,V(NR+1,NR+1),LDV)
                  END IF
                  CALL DORMQR('L','N',N,N,NR,WORK(2*N+1),N,WORK(N+1),
     $                 V,LDV,WORK(2*N+N*NR+NR+1),LWORK-2*N-N*NR-NR,IERR)
               END IF
*
            ELSE IF ( CONDR2 .LT. COND_OK ) THEN
*
* :)           .. the input matrix A is very likely a relative of
*              the Kahan matrix :)
*              The matrix R2 is inverted. The solution of the matrix equation
*              is Q3^T*V3 = the product of the Jacobi rotations (appplied to
*              the lower triangular L3 from the LQ factorization of
*              R2=L3*Q3), pre-multiplied with the transposed Q3.
               CALL DGESVJ( 'L', 'U', 'N', NR, NR, V, LDV, SVA, NR, U,
     $              LDU, WORK(2*N+N*NR+NR+1), LWORK-2*N-N*NR-NR, INFO )
               SCALEM  = WORK(2*N+N*NR+NR+1)
               NUMRANK = IDNINT(WORK(2*N+N*NR+NR+2))
               DO 3870 p = 1, NR
                  CALL DCOPY( NR, V(1,p), 1, U(1,p), 1 )
                  CALL DSCAL( NR, SVA(p),    U(1,p), 1 )
 3870          CONTINUE
               CALL DTRSM('L','U','N','N',NR,NR,ONE,WORK(2*N+1),N,U,LDU)
*              .. apply the permutation from the second QR factorization
               DO 873 q = 1, NR
                  DO 872 p = 1, NR
                     WORK(2*N+N*NR+NR+IWORK(N+p)) = U(p,q)
 872              CONTINUE
                  DO 874 p = 1, NR
                     U(p,q) = WORK(2*N+N*NR+NR+p)
 874              CONTINUE
 873           CONTINUE
               IF ( NR .LT. N ) THEN
                  CALL DLASET( 'A',N-NR,NR,ZERO,ZERO,V(NR+1,1),LDV )
                  CALL DLASET( 'A',NR,N-NR,ZERO,ZERO,V(1,NR+1),LDV )
                  CALL DLASET( 'A',N-NR,N-NR,ZERO,ONE,V(NR+1,NR+1),LDV )
               END IF
               CALL DORMQR( 'L','N',N,N,NR,WORK(2*N+1),N,WORK(N+1),
     $              V,LDV,WORK(2*N+N*NR+NR+1),LWORK-2*N-N*NR-NR,IERR )
            ELSE
*              Last line of defense.
* #:(          This is a rather pathological case: no scaled condition
*              improvement after two pivoted QR factorizations. Other
*              possibility is that the rank revealing QR factorization
*              or the condition estimator has failed, or the COND_OK
*              is set very close to ONE (which is unnecessary). Normally,
*              this branch should never be executed, but in rare cases of
*              failure of the RRQR or condition estimator, the last line of
*              defense ensures that DGEJSV completes the task.
*              Compute the full SVD of L3 using DGESVJ with explicit
*              accumulation of Jacobi rotations.
               CALL DGESVJ( 'L', 'U', 'V', NR, NR, V, LDV, SVA, NR, U,
     $              LDU, WORK(2*N+N*NR+NR+1), LWORK-2*N-N*NR-NR, INFO )
               SCALEM  = WORK(2*N+N*NR+NR+1)
               NUMRANK = IDNINT(WORK(2*N+N*NR+NR+2))
               IF ( NR .LT. N ) THEN
                  CALL DLASET( 'A',N-NR,NR,ZERO,ZERO,V(NR+1,1),LDV )
                  CALL DLASET( 'A',NR,N-NR,ZERO,ZERO,V(1,NR+1),LDV )
                  CALL DLASET( 'A',N-NR,N-NR,ZERO,ONE,V(NR+1,NR+1),LDV )
               END IF
               CALL DORMQR( 'L','N',N,N,NR,WORK(2*N+1),N,WORK(N+1),
     $              V,LDV,WORK(2*N+N*NR+NR+1),LWORK-2*N-N*NR-NR,IERR )
*
               CALL DORMLQ( 'L', 'T', NR, NR, NR, WORK(2*N+1), N,
     $              WORK(2*N+N*NR+1), U, LDU, WORK(2*N+N*NR+NR+1),
     $              LWORK-2*N-N*NR-NR, IERR )
               DO 773 q = 1, NR
                  DO 772 p = 1, NR
                     WORK(2*N+N*NR+NR+IWORK(N+p)) = U(p,q)
 772              CONTINUE
                  DO 774 p = 1, NR
                     U(p,q) = WORK(2*N+N*NR+NR+p)
 774              CONTINUE
 773           CONTINUE
*
            END IF
*
*           Permute the rows of V using the (column) permutation from the
*           first QRF. Also, scale the columns to make them unit in
*           Euclidean norm. This applies to all cases.
*
            TEMP1 = DSQRT(DBLE(N)) * EPSLN
            DO 1972 q = 1, N
               DO 972 p = 1, N
                  WORK(2*N+N*NR+NR+IWORK(p)) = V(p,q)
  972          CONTINUE
               DO 973 p = 1, N
                  V(p,q) = WORK(2*N+N*NR+NR+p)
  973          CONTINUE
               XSC = ONE / DNRM2( N, V(1,q), 1 )
               IF ( (XSC .LT. (ONE-TEMP1)) .OR. (XSC .GT. (ONE+TEMP1)) )
     $           CALL DSCAL( N, XSC, V(1,q), 1 )
 1972       CONTINUE
*           At this moment, V contains the right singular vectors of A.
*           Next, assemble the left singular vector matrix U (M x N).
            IF ( NR .LT. M ) THEN
               CALL DLASET( 'A', M-NR, NR, ZERO, ZERO, U(NR+1,1), LDU )
               IF ( NR .LT. N1 ) THEN
                  CALL DLASET('A',NR,N1-NR,ZERO,ZERO,U(1,NR+1),LDU)
                  CALL DLASET('A',M-NR,N1-NR,ZERO,ONE,U(NR+1,NR+1),LDU)
               END IF
            END IF
*
*           The Q matrix from the first QRF is built into the left singular
*           matrix U. This applies to all cases.
*
            CALL DORMQR( 'Left', 'No_Tr', M, N1, N, A, LDA, WORK, U,
     $           LDU, WORK(N+1), LWORK-N, IERR )

*           The columns of U are normalized. The cost is O(M*N) flops.
            TEMP1 = DSQRT(DBLE(M)) * EPSLN
            DO 1973 p = 1, NR
               XSC = ONE / DNRM2( M, U(1,p), 1 )
               IF ( (XSC .LT. (ONE-TEMP1)) .OR. (XSC .GT. (ONE+TEMP1)) )
     $          CALL DSCAL( M, XSC, U(1,p), 1 )
 1973       CONTINUE
*
*           If the initial QRF is computed with row pivoting, the left
*           singular vectors must be adjusted.
*
            IF ( ROWPIV )
     $          CALL DLASWP( N1, U, LDU, 1, M-1, IWORK(2*N+1), -1 )
*
         ELSE
*
*        .. the initial matrix A has almost orthogonal columns and
*        the second QRF is not needed
*
            CALL DLACPY( 'Upper', N, N, A, LDA, WORK(N+1), N )
            IF ( L2PERT ) THEN
               XSC = DSQRT(SMALL)
               DO 5970 p = 2, N
                  TEMP1 = XSC * WORK( N + (p-1)*N + p )
                  DO 5971 q = 1, p - 1
                     WORK(N+(q-1)*N+p)=-DSIGN(TEMP1,WORK(N+(p-1)*N+q))
 5971             CONTINUE
 5970          CONTINUE
            ELSE
               CALL DLASET( 'Lower',N-1,N-1,ZERO,ZERO,WORK(N+2),N )
            END IF
*
            CALL DGESVJ( 'Upper', 'U', 'N', N, N, WORK(N+1), N, SVA,
     $           N, U, LDU, WORK(N+N*N+1), LWORK-N-N*N, INFO )
*
            SCALEM  = WORK(N+N*N+1)
            NUMRANK = IDNINT(WORK(N+N*N+2))
            DO 6970 p = 1, N
               CALL DCOPY( N, WORK(N+(p-1)*N+1), 1, U(1,p), 1 )
               CALL DSCAL( N, SVA(p), WORK(N+(p-1)*N+1), 1 )
 6970       CONTINUE
*
            CALL DTRSM( 'Left', 'Upper', 'NoTrans', 'No UD', N, N,
     $           ONE, A, LDA, WORK(N+1), N )
            DO 6972 p = 1, N
               CALL DCOPY( N, WORK(N+p), N, V(IWORK(p),1), LDV )
 6972       CONTINUE
            TEMP1 = DSQRT(DBLE(N))*EPSLN
            DO 6971 p = 1, N
               XSC = ONE / DNRM2( N, V(1,p), 1 )
               IF ( (XSC .LT. (ONE-TEMP1)) .OR. (XSC .GT. (ONE+TEMP1)) )
     $            CALL DSCAL( N, XSC, V(1,p), 1 )
 6971       CONTINUE
*
*           Assemble the left singular vector matrix U (M x N).
*
            IF ( N .LT. M ) THEN
               CALL DLASET( 'A',  M-N, N, ZERO, ZERO, U(N+1,1), LDU )
               IF ( N .LT. N1 ) THEN
                  CALL DLASET( 'A',N,  N1-N, ZERO, ZERO,  U(1,N+1),LDU )
                  CALL DLASET( 'A',M-N,N1-N, ZERO, ONE,U(N+1,N+1),LDU )
               END IF
            END IF
            CALL DORMQR( 'Left', 'No Tr', M, N1, N, A, LDA, WORK, U,
     $           LDU, WORK(N+1), LWORK-N, IERR )
            TEMP1 = DSQRT(DBLE(M))*EPSLN
            DO 6973 p = 1, N1
               XSC = ONE / DNRM2( M, U(1,p), 1 )
               IF ( (XSC .LT. (ONE-TEMP1)) .OR. (XSC .GT. (ONE+TEMP1)) )
     $            CALL DSCAL( M, XSC, U(1,p), 1 )
 6973       CONTINUE
*
            IF ( ROWPIV )
     $         CALL DLASWP( N1, U, LDU, 1, M-1, IWORK(2*N+1), -1 )
*
         END IF
*
*        end of the  >> almost orthogonal case <<  in the full SVD
*
         ELSE
*
*        This branch deploys a preconditioned Jacobi SVD with explicitly
*        accumulated rotations. It is included as optional, mainly for
*        experimental purposes. It does perfom well, and can also be used.
*        In this implementation, this branch will be automatically activated
*        if the  condition number sigma_max(A) / sigma_min(A) is predicted
*        to be greater than the overflow threshold. This is because the
*        a posteriori computation of the singular vectors assumes robust
*        implementation of BLAS and some LAPACK procedures, capable of working
*        in presence of extreme values. Since that is not always the case, ...
*
         DO 7968 p = 1, NR
            CALL DCOPY( N-p+1, A(p,p), LDA, V(p,p), 1 )
 7968    CONTINUE
*
         IF ( L2PERT ) THEN
            XSC = DSQRT(SMALL/EPSLN)
            DO 5969 q = 1, NR
               TEMP1 = XSC*DABS( V(q,q) )
               DO 5968 p = 1, N
                  IF ( ( p .GT. q ) .AND. ( DABS(V(p,q)) .LE. TEMP1 )
     $                .OR. ( p .LT. q ) )
     $                V(p,q) = DSIGN( TEMP1, V(p,q) )
                  IF ( p .LT. q ) V(p,q) = - V(p,q)
 5968          CONTINUE
 5969       CONTINUE
         ELSE
            CALL DLASET( 'U', NR-1, NR-1, ZERO, ZERO, V(1,2), LDV )
         END IF

         CALL DGEQRF( N, NR, V, LDV, WORK(N+1), WORK(2*N+1),
     $        LWORK-2*N, IERR )
         CALL DLACPY( 'L', N, NR, V, LDV, WORK(2*N+1), N )
*
         DO 7969 p = 1, NR
            CALL DCOPY( NR-p+1, V(p,p), LDV, U(p,p), 1 )
 7969    CONTINUE

         IF ( L2PERT ) THEN
            XSC = DSQRT(SMALL/EPSLN)
            DO 9970 q = 2, NR
               DO 9971 p = 1, q - 1
                  TEMP1 = XSC * MIN(DABS(U(p,p)),DABS(U(q,q)))
                  U(p,q) = - DSIGN( TEMP1, U(q,p) )
 9971          CONTINUE
 9970       CONTINUE
         ELSE
            CALL DLASET('U', NR-1, NR-1, ZERO, ZERO, U(1,2), LDU )
         END IF

         CALL DGESVJ( 'G', 'U', 'V', NR, NR, U, LDU, SVA,
     $        N, V, LDV, WORK(2*N+N*NR+1), LWORK-2*N-N*NR, INFO )
         SCALEM  = WORK(2*N+N*NR+1)
         NUMRANK = IDNINT(WORK(2*N+N*NR+2))

         IF ( NR .LT. N ) THEN
            CALL DLASET( 'A',N-NR,NR,ZERO,ZERO,V(NR+1,1),LDV )
            CALL DLASET( 'A',NR,N-NR,ZERO,ZERO,V(1,NR+1),LDV )
            CALL DLASET( 'A',N-NR,N-NR,ZERO,ONE,V(NR+1,NR+1),LDV )
         END IF

         CALL DORMQR( 'L','N',N,N,NR,WORK(2*N+1),N,WORK(N+1),
     $        V,LDV,WORK(2*N+N*NR+NR+1),LWORK-2*N-N*NR-NR,IERR )
*
*           Permute the rows of V using the (column) permutation from the
*           first QRF. Also, scale the columns to make them unit in
*           Euclidean norm. This applies to all cases.
*
            TEMP1 = DSQRT(DBLE(N)) * EPSLN
            DO 7972 q = 1, N
               DO 8972 p = 1, N
                  WORK(2*N+N*NR+NR+IWORK(p)) = V(p,q)
 8972          CONTINUE
               DO 8973 p = 1, N
                  V(p,q) = WORK(2*N+N*NR+NR+p)
 8973          CONTINUE
               XSC = ONE / DNRM2( N, V(1,q), 1 )
               IF ( (XSC .LT. (ONE-TEMP1)) .OR. (XSC .GT. (ONE+TEMP1)) )
     $           CALL DSCAL( N, XSC, V(1,q), 1 )
 7972       CONTINUE
*
*           At this moment, V contains the right singular vectors of A.
*           Next, assemble the left singular vector matrix U (M x N).
*
         IF ( NR .LT. M ) THEN
            CALL DLASET( 'A',  M-NR, NR, ZERO, ZERO, U(NR+1,1), LDU )
            IF ( NR .LT. N1 ) THEN
               CALL DLASET( 'A',NR,  N1-NR, ZERO, ZERO,  U(1,NR+1),LDU )
               CALL DLASET( 'A',M-NR,N1-NR, ZERO, ONE,U(NR+1,NR+1),LDU )
            END IF
         END IF
*
         CALL DORMQR( 'Left', 'No Tr', M, N1, N, A, LDA, WORK, U,
     $        LDU, WORK(N+1), LWORK-N, IERR )
*
            IF ( ROWPIV )
     $         CALL DLASWP( N1, U, LDU, 1, M-1, IWORK(2*N+1), -1 )
*
*
         END IF
         IF ( TRANSP ) THEN
*           .. swap U and V because the procedure worked on A^t
            DO 6974 p = 1, N
               CALL DSWAP( N, U(1,p), 1, V(1,p), 1 )
 6974       CONTINUE
         END IF
*
      END IF
*     end of the full SVD
*
*     Undo scaling, if necessary (and possible)
*
      IF ( USCAL2 .LE. (BIG/SVA(1))*USCAL1 ) THEN
         CALL DLASCL( 'G', 0, 0, USCAL1, USCAL2, NR, 1, SVA, N, IERR )
         USCAL1 = ONE
         USCAL2 = ONE
      END IF
*
      IF ( NR .LT. N ) THEN
         DO 3004 p = NR+1, N
            SVA(p) = ZERO
 3004    CONTINUE
      END IF
*
      WORK(1) = USCAL2 * SCALEM
      WORK(2) = USCAL1
      IF ( ERREST ) WORK(3) = SCONDA
      IF ( LSVEC .AND. RSVEC ) THEN
         WORK(4) = CONDR1
         WORK(5) = CONDR2
      END IF
      IF ( L2TRAN ) THEN
         WORK(6) = ENTRA
         WORK(7) = ENTRAT
      END IF
*
      IWORK(1) = NR
      IWORK(2) = NUMRANK
      IWORK(3) = WARNING
*
      RETURN
*     ..
*     .. END OF DGEJSV
*     ..
      END
*
*> \brief \b DGELQ2 computes the LQ factorization of a general rectangular matrix using an unblocked algorithm.
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGELQ2 + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgelq2.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgelq2.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgelq2.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGELQ2( M, N, A, LDA, TAU, WORK, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, LDA, M, N
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGELQ2 computes an LQ factorization of a real m by n matrix A:
*> A = L * Q.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A.  M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the m by n matrix A.
*>          On exit, the elements on and below the diagonal of the array
*>          contain the m by min(m,n) lower trapezoidal matrix L (L is
*>          lower triangular if m <= n); the elements above the diagonal,
*>          with the array TAU, represent the orthogonal matrix Q as a
*>          product of elementary reflectors (see Further Details).
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,M).
*> \endverbatim
*>
*> \param[out] TAU
*> \verbatim
*>          TAU is DOUBLE PRECISION array, dimension (min(M,N))
*>          The scalar factors of the elementary reflectors (see Further
*>          Details).
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (M)
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0: successful exit
*>          < 0: if INFO = -i, the i-th argument had an illegal value
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEcomputational
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>  The matrix Q is represented as a product of elementary reflectors
*>
*>     Q = H(k) . . . H(2) H(1), where k = min(m,n).
*>
*>  Each H(i) has the form
*>
*>     H(i) = I - tau * v * v**T
*>
*>  where tau is a real scalar, and v is a real vector with
*>  v(1:i-1) = 0 and v(i) = 1; v(i+1:n) is stored on exit in A(i,i+1:n),
*>  and tau in TAU(i).
*> \endverbatim
*>
*  =====================================================================
      SUBROUTINE DGELQ2( M, N, A, LDA, TAU, WORK, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER            INFO, LDA, M, N
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ONE
      PARAMETER          ( ONE = 1.0D+0 )
*     ..
*     .. Local Scalars ..
      INTEGER            I, K
      DOUBLE PRECISION   AII
*     ..
*     .. External Subroutines ..
      EXTERNAL           DLARF, DLARFG, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, MIN
*     ..
*     .. Executable Statements ..
*
*     Test the input arguments
*
      INFO = 0
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -4
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGELQ2', -INFO )
         RETURN
      END IF
*
      K = MIN( M, N )
*
      DO 10 I = 1, K
*
*        Generate elementary reflector H(i) to annihilate A(i,i+1:n)
*
         CALL DLARFG( N-I+1, A( I, I ), A( I, MIN( I+1, N ) ), LDA,
     $                TAU( I ) )
         IF( I.LT.M ) THEN
*
*           Apply H(i) to A(i+1:m,i:n) from the right
*
            AII = A( I, I )
            A( I, I ) = ONE
            CALL DLARF( 'Right', M-I, N-I+1, A( I, I ), LDA, TAU( I ),
     $                  A( I+1, I ), LDA, WORK )
            A( I, I ) = AII
         END IF
   10 CONTINUE
      RETURN
*
*     End of DGELQ2
*
      END
*> \brief \b DGELQF
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGELQF + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgelqf.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgelqf.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgelqf.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGELQF( M, N, A, LDA, TAU, WORK, LWORK, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, LDA, LWORK, M, N
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGELQF computes an LQ factorization of a real M-by-N matrix A:
*> A = L * Q.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A.  M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the M-by-N matrix A.
*>          On exit, the elements on and below the diagonal of the array
*>          contain the m-by-min(m,n) lower trapezoidal matrix L (L is
*>          lower triangular if m <= n); the elements above the diagonal,
*>          with the array TAU, represent the orthogonal matrix Q as a
*>          product of elementary reflectors (see Further Details).
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,M).
*> \endverbatim
*>
*> \param[out] TAU
*> \verbatim
*>          TAU is DOUBLE PRECISION array, dimension (min(M,N))
*>          The scalar factors of the elementary reflectors (see Further
*>          Details).
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK))
*>          On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
*> \endverbatim
*>
*> \param[in] LWORK
*> \verbatim
*>          LWORK is INTEGER
*>          The dimension of the array WORK.  LWORK >= max(1,M).
*>          For optimum performance LWORK >= M*NB, where NB is the
*>          optimal blocksize.
*>
*>          If LWORK = -1, then a workspace query is assumed; the routine
*>          only calculates the optimal size of the WORK array, returns
*>          this value as the first entry of the WORK array, and no error
*>          message related to LWORK is issued by XERBLA.
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEcomputational
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>  The matrix Q is represented as a product of elementary reflectors
*>
*>     Q = H(k) . . . H(2) H(1), where k = min(m,n).
*>
*>  Each H(i) has the form
*>
*>     H(i) = I - tau * v * v**T
*>
*>  where tau is a real scalar, and v is a real vector with
*>  v(1:i-1) = 0 and v(i) = 1; v(i+1:n) is stored on exit in A(i,i+1:n),
*>  and tau in TAU(i).
*> \endverbatim
*>
*  =====================================================================
      SUBROUTINE DGELQF( M, N, A, LDA, TAU, WORK, LWORK, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER            INFO, LDA, LWORK, M, N
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Local Scalars ..
      LOGICAL            LQUERY
      INTEGER            I, IB, IINFO, IWS, K, LDWORK, LWKOPT, NB,
     $                   NBMIN, NX
*     ..
*     .. External Subroutines ..
      EXTERNAL           DGELQ2, DLARFB, DLARFT, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, MIN
*     ..
*     .. External Functions ..
      INTEGER            ILAENV
      EXTERNAL           ILAENV
*     ..
*     .. Executable Statements ..
*
*     Test the input arguments
*
      INFO = 0
      NB = ILAENV( 1, 'DGELQF', ' ', M, N, -1, -1 )
      LWKOPT = M*NB
      WORK( 1 ) = LWKOPT
      LQUERY = ( LWORK.EQ.-1 )
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -4
      ELSE IF( LWORK.LT.MAX( 1, M ) .AND. .NOT.LQUERY ) THEN
         INFO = -7
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGELQF', -INFO )
         RETURN
      ELSE IF( LQUERY ) THEN
         RETURN
      END IF
*
*     Quick return if possible
*
      K = MIN( M, N )
      IF( K.EQ.0 ) THEN
         WORK( 1 ) = 1
         RETURN
      END IF
*
      NBMIN = 2
      NX = 0
      IWS = M
      IF( NB.GT.1 .AND. NB.LT.K ) THEN
*
*        Determine when to cross over from blocked to unblocked code.
*
         NX = MAX( 0, ILAENV( 3, 'DGELQF', ' ', M, N, -1, -1 ) )
         IF( NX.LT.K ) THEN
*
*           Determine if workspace is large enough for blocked code.
*
            LDWORK = M
            IWS = LDWORK*NB
            IF( LWORK.LT.IWS ) THEN
*
*              Not enough workspace to use optimal NB:  reduce NB and
*              determine the minimum value of NB.
*
               NB = LWORK / LDWORK
               NBMIN = MAX( 2, ILAENV( 2, 'DGELQF', ' ', M, N, -1,
     $                 -1 ) )
            END IF
         END IF
      END IF
*
      IF( NB.GE.NBMIN .AND. NB.LT.K .AND. NX.LT.K ) THEN
*
*        Use blocked code initially
*
         DO 10 I = 1, K - NX, NB
            IB = MIN( K-I+1, NB )
*
*           Compute the LQ factorization of the current block
*           A(i:i+ib-1,i:n)
*
            CALL DGELQ2( IB, N-I+1, A( I, I ), LDA, TAU( I ), WORK,
     $                   IINFO )
            IF( I+IB.LE.M ) THEN
*
*              Form the triangular factor of the block reflector
*              H = H(i) H(i+1) . . . H(i+ib-1)
*
               CALL DLARFT( 'Forward', 'Rowwise', N-I+1, IB, A( I, I ),
     $                      LDA, TAU( I ), WORK, LDWORK )
*
*              Apply H to A(i+ib:m,i:n) from the right
*
               CALL DLARFB( 'Right', 'No transpose', 'Forward',
     $                      'Rowwise', M-I-IB+1, N-I+1, IB, A( I, I ),
     $                      LDA, WORK, LDWORK, A( I+IB, I ), LDA,
     $                      WORK( IB+1 ), LDWORK )
            END IF
   10    CONTINUE
      ELSE
         I = 1
      END IF
*
*     Use unblocked code to factor the last or only block.
*
      IF( I.LE.K )
     $   CALL DGELQ2( M-I+1, N-I+1, A( I, I ), LDA, TAU( I ), WORK,
     $                IINFO )
*
      WORK( 1 ) = IWS
      RETURN
*
*     End of DGELQF
*
      END
*> \brief <b> DGELS solves overdetermined or underdetermined systems for GE matrices</b>
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGELS + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgels.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgels.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgels.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGELS( TRANS, M, N, NRHS, A, LDA, B, LDB, WORK, LWORK,
*                         INFO )
*
*       .. Scalar Arguments ..
*       CHARACTER          TRANS
*       INTEGER            INFO, LDA, LDB, LWORK, M, N, NRHS
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   A( LDA, * ), B( LDB, * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGELS solves overdetermined or underdetermined real linear systems
*> involving an M-by-N matrix A, or its transpose, using a QR or LQ
*> factorization of A.  It is assumed that A has full rank.
*>
*> The following options are provided:
*>
*> 1. If TRANS = 'N' and m >= n:  find the least squares solution of
*>    an overdetermined system, i.e., solve the least squares problem
*>                 minimize || B - A*X ||.
*>
*> 2. If TRANS = 'N' and m < n:  find the minimum norm solution of
*>    an underdetermined system A * X = B.
*>
*> 3. If TRANS = 'T' and m >= n:  find the minimum norm solution of
*>    an underdetermined system A**T * X = B.
*>
*> 4. If TRANS = 'T' and m < n:  find the least squares solution of
*>    an overdetermined system, i.e., solve the least squares problem
*>                 minimize || B - A**T * X ||.
*>
*> Several right hand side vectors b and solution vectors x can be
*> handled in a single call; they are stored as the columns of the
*> M-by-NRHS right hand side matrix B and the N-by-NRHS solution
*> matrix X.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] TRANS
*> \verbatim
*>          TRANS is CHARACTER*1
*>          = 'N': the linear system involves A;
*>          = 'T': the linear system involves A**T.
*> \endverbatim
*>
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A.  M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in] NRHS
*> \verbatim
*>          NRHS is INTEGER
*>          The number of right hand sides, i.e., the number of
*>          columns of the matrices B and X. NRHS >=0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the M-by-N matrix A.
*>          On exit,
*>            if M >= N, A is overwritten by details of its QR
*>                       factorization as returned by DGEQRF;
*>            if M <  N, A is overwritten by details of its LQ
*>                       factorization as returned by DGELQF.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,M).
*> \endverbatim
*>
*> \param[in,out] B
*> \verbatim
*>          B is DOUBLE PRECISION array, dimension (LDB,NRHS)
*>          On entry, the matrix B of right hand side vectors, stored
*>          columnwise; B is M-by-NRHS if TRANS = 'N', or N-by-NRHS
*>          if TRANS = 'T'.
*>          On exit, if INFO = 0, B is overwritten by the solution
*>          vectors, stored columnwise:
*>          if TRANS = 'N' and m >= n, rows 1 to n of B contain the least
*>          squares solution vectors; the residual sum of squares for the
*>          solution in each column is given by the sum of squares of
*>          elements N+1 to M in that column;
*>          if TRANS = 'N' and m < n, rows 1 to N of B contain the
*>          minimum norm solution vectors;
*>          if TRANS = 'T' and m >= n, rows 1 to M of B contain the
*>          minimum norm solution vectors;
*>          if TRANS = 'T' and m < n, rows 1 to M of B contain the
*>          least squares solution vectors; the residual sum of squares
*>          for the solution in each column is given by the sum of
*>          squares of elements M+1 to N in that column.
*> \endverbatim
*>
*> \param[in] LDB
*> \verbatim
*>          LDB is INTEGER
*>          The leading dimension of the array B. LDB >= MAX(1,M,N).
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK))
*>          On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
*> \endverbatim
*>
*> \param[in] LWORK
*> \verbatim
*>          LWORK is INTEGER
*>          The dimension of the array WORK.
*>          LWORK >= max( 1, MN + max( MN, NRHS ) ).
*>          For optimal performance,
*>          LWORK >= max( 1, MN + max( MN, NRHS )*NB ).
*>          where MN = min(M,N) and NB is the optimum block size.
*>
*>          If LWORK = -1, then a workspace query is assumed; the routine
*>          only calculates the optimal size of the WORK array, returns
*>          this value as the first entry of the WORK array, and no error
*>          message related to LWORK is issued by XERBLA.
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value
*>          > 0:  if INFO =  i, the i-th diagonal element of the
*>                triangular factor of A is zero, so that A does not have
*>                full rank; the least squares solution could not be
*>                computed.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEsolve
*
*  =====================================================================
      SUBROUTINE DGELS( TRANS, M, N, NRHS, A, LDA, B, LDB, WORK, LWORK,
     $                  INFO )
*
*  -- LAPACK driver routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      CHARACTER          TRANS
      INTEGER            INFO, LDA, LDB, LWORK, M, N, NRHS
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   A( LDA, * ), B( LDB, * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ZERO, ONE
      PARAMETER          ( ZERO = 0.0D0, ONE = 1.0D0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            LQUERY, TPSD
      INTEGER            BROW, I, IASCL, IBSCL, J, MN, NB, SCLLEN, WSIZE
      DOUBLE PRECISION   ANRM, BIGNUM, BNRM, SMLNUM
*     ..
*     .. Local Arrays ..
      DOUBLE PRECISION   RWORK( 1 )
*     ..
*     .. External Functions ..
      LOGICAL            LSAME
      INTEGER            ILAENV
      DOUBLE PRECISION   DLAMCH, DLANGE
      EXTERNAL           LSAME, ILAENV, DLABAD, DLAMCH, DLANGE
*     ..
*     .. External Subroutines ..
      EXTERNAL           DGELQF, DGEQRF, DLASCL, DLASET, DORMLQ, DORMQR,
     $                   DTRTRS, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          DBLE, MAX, MIN
*     ..
*     .. Executable Statements ..
*
*     Test the input arguments.
*
      INFO = 0
      MN = MIN( M, N )
      LQUERY = ( LWORK.EQ.-1 )
      IF( .NOT.( LSAME( TRANS, 'N' ) .OR. LSAME( TRANS, 'T' ) ) ) THEN
         INFO = -1
      ELSE IF( M.LT.0 ) THEN
         INFO = -2
      ELSE IF( N.LT.0 ) THEN
         INFO = -3
      ELSE IF( NRHS.LT.0 ) THEN
         INFO = -4
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -6
      ELSE IF( LDB.LT.MAX( 1, M, N ) ) THEN
         INFO = -8
      ELSE IF( LWORK.LT.MAX( 1, MN+MAX( MN, NRHS ) ) .AND. .NOT.LQUERY )
     $          THEN
         INFO = -10
      END IF
*
*     Figure out optimal block size
*
      IF( INFO.EQ.0 .OR. INFO.EQ.-10 ) THEN
*
         TPSD = .TRUE.
         IF( LSAME( TRANS, 'N' ) )
     $      TPSD = .FALSE.
*
         IF( M.GE.N ) THEN
            NB = ILAENV( 1, 'DGEQRF', ' ', M, N, -1, -1 )
            IF( TPSD ) THEN
               NB = MAX( NB, ILAENV( 1, 'DORMQR', 'LN', M, NRHS, N,
     $              -1 ) )
            ELSE
               NB = MAX( NB, ILAENV( 1, 'DORMQR', 'LT', M, NRHS, N,
     $              -1 ) )
            END IF
         ELSE
            NB = ILAENV( 1, 'DGELQF', ' ', M, N, -1, -1 )
            IF( TPSD ) THEN
               NB = MAX( NB, ILAENV( 1, 'DORMLQ', 'LT', N, NRHS, M,
     $              -1 ) )
            ELSE
               NB = MAX( NB, ILAENV( 1, 'DORMLQ', 'LN', N, NRHS, M,
     $              -1 ) )
            END IF
         END IF
*
         WSIZE = MAX( 1, MN+MAX( MN, NRHS )*NB )
         WORK( 1 ) = DBLE( WSIZE )
*
      END IF
*
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGELS ', -INFO )
         RETURN
      ELSE IF( LQUERY ) THEN
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( MIN( M, N, NRHS ).EQ.0 ) THEN
         CALL DLASET( 'Full', MAX( M, N ), NRHS, ZERO, ZERO, B, LDB )
         RETURN
      END IF
*
*     Get machine parameters
*
      SMLNUM = DLAMCH( 'S' ) / DLAMCH( 'P' )
      BIGNUM = ONE / SMLNUM
      CALL DLABAD( SMLNUM, BIGNUM )
*
*     Scale A, B if max element outside range [SMLNUM,BIGNUM]
*
      ANRM = DLANGE( 'M', M, N, A, LDA, RWORK )
      IASCL = 0
      IF( ANRM.GT.ZERO .AND. ANRM.LT.SMLNUM ) THEN
*
*        Scale matrix norm up to SMLNUM
*
         CALL DLASCL( 'G', 0, 0, ANRM, SMLNUM, M, N, A, LDA, INFO )
         IASCL = 1
      ELSE IF( ANRM.GT.BIGNUM ) THEN
*
*        Scale matrix norm down to BIGNUM
*
         CALL DLASCL( 'G', 0, 0, ANRM, BIGNUM, M, N, A, LDA, INFO )
         IASCL = 2
      ELSE IF( ANRM.EQ.ZERO ) THEN
*
*        Matrix all zero. Return zero solution.
*
         CALL DLASET( 'F', MAX( M, N ), NRHS, ZERO, ZERO, B, LDB )
         GO TO 50
      END IF
*
      BROW = M
      IF( TPSD )
     $   BROW = N
      BNRM = DLANGE( 'M', BROW, NRHS, B, LDB, RWORK )
      IBSCL = 0
      IF( BNRM.GT.ZERO .AND. BNRM.LT.SMLNUM ) THEN
*
*        Scale matrix norm up to SMLNUM
*
         CALL DLASCL( 'G', 0, 0, BNRM, SMLNUM, BROW, NRHS, B, LDB,
     $                INFO )
         IBSCL = 1
      ELSE IF( BNRM.GT.BIGNUM ) THEN
*
*        Scale matrix norm down to BIGNUM
*
         CALL DLASCL( 'G', 0, 0, BNRM, BIGNUM, BROW, NRHS, B, LDB,
     $                INFO )
         IBSCL = 2
      END IF
*
      IF( M.GE.N ) THEN
*
*        compute QR factorization of A
*
         CALL DGEQRF( M, N, A, LDA, WORK( 1 ), WORK( MN+1 ), LWORK-MN,
     $                INFO )
*
*        workspace at least N, optimally N*NB
*
         IF( .NOT.TPSD ) THEN
*
*           Least-Squares Problem min || A * X - B ||
*
*           B(1:M,1:NRHS) := Q**T * B(1:M,1:NRHS)
*
            CALL DORMQR( 'Left', 'Transpose', M, NRHS, N, A, LDA,
     $                   WORK( 1 ), B, LDB, WORK( MN+1 ), LWORK-MN,
     $                   INFO )
*
*           workspace at least NRHS, optimally NRHS*NB
*
*           B(1:N,1:NRHS) := inv(R) * B(1:N,1:NRHS)
*
            CALL DTRTRS( 'Upper', 'No transpose', 'Non-unit', N, NRHS,
     $                   A, LDA, B, LDB, INFO )
*
            IF( INFO.GT.0 ) THEN
               RETURN
            END IF
*
            SCLLEN = N
*
         ELSE
*
*           Underdetermined system of equations A**T * X = B
*
*           B(1:N,1:NRHS) := inv(R**T) * B(1:N,1:NRHS)
*
            CALL DTRTRS( 'Upper', 'Transpose', 'Non-unit', N, NRHS,
     $                   A, LDA, B, LDB, INFO )
*
            IF( INFO.GT.0 ) THEN
               RETURN
            END IF
*
*           B(N+1:M,1:NRHS) = ZERO
*
            DO 20 J = 1, NRHS
               DO 10 I = N + 1, M
                  B( I, J ) = ZERO
   10          CONTINUE
   20       CONTINUE
*
*           B(1:M,1:NRHS) := Q(1:N,:) * B(1:N,1:NRHS)
*
            CALL DORMQR( 'Left', 'No transpose', M, NRHS, N, A, LDA,
     $                   WORK( 1 ), B, LDB, WORK( MN+1 ), LWORK-MN,
     $                   INFO )
*
*           workspace at least NRHS, optimally NRHS*NB
*
            SCLLEN = M
*
         END IF
*
      ELSE
*
*        Compute LQ factorization of A
*
         CALL DGELQF( M, N, A, LDA, WORK( 1 ), WORK( MN+1 ), LWORK-MN,
     $                INFO )
*
*        workspace at least M, optimally M*NB.
*
         IF( .NOT.TPSD ) THEN
*
*           underdetermined system of equations A * X = B
*
*           B(1:M,1:NRHS) := inv(L) * B(1:M,1:NRHS)
*
            CALL DTRTRS( 'Lower', 'No transpose', 'Non-unit', M, NRHS,
     $                   A, LDA, B, LDB, INFO )
*
            IF( INFO.GT.0 ) THEN
               RETURN
            END IF
*
*           B(M+1:N,1:NRHS) = 0
*
            DO 40 J = 1, NRHS
               DO 30 I = M + 1, N
                  B( I, J ) = ZERO
   30          CONTINUE
   40       CONTINUE
*
*           B(1:N,1:NRHS) := Q(1:N,:)**T * B(1:M,1:NRHS)
*
            CALL DORMLQ( 'Left', 'Transpose', N, NRHS, M, A, LDA,
     $                   WORK( 1 ), B, LDB, WORK( MN+1 ), LWORK-MN,
     $                   INFO )
*
*           workspace at least NRHS, optimally NRHS*NB
*
            SCLLEN = N
*
         ELSE
*
*           overdetermined system min || A**T * X - B ||
*
*           B(1:N,1:NRHS) := Q * B(1:N,1:NRHS)
*
            CALL DORMLQ( 'Left', 'No transpose', N, NRHS, M, A, LDA,
     $                   WORK( 1 ), B, LDB, WORK( MN+1 ), LWORK-MN,
     $                   INFO )
*
*           workspace at least NRHS, optimally NRHS*NB
*
*           B(1:M,1:NRHS) := inv(L**T) * B(1:M,1:NRHS)
*
            CALL DTRTRS( 'Lower', 'Transpose', 'Non-unit', M, NRHS,
     $                   A, LDA, B, LDB, INFO )
*
            IF( INFO.GT.0 ) THEN
               RETURN
            END IF
*
            SCLLEN = M
*
         END IF
*
      END IF
*
*     Undo scaling
*
      IF( IASCL.EQ.1 ) THEN
         CALL DLASCL( 'G', 0, 0, ANRM, SMLNUM, SCLLEN, NRHS, B, LDB,
     $                INFO )
      ELSE IF( IASCL.EQ.2 ) THEN
         CALL DLASCL( 'G', 0, 0, ANRM, BIGNUM, SCLLEN, NRHS, B, LDB,
     $                INFO )
      END IF
      IF( IBSCL.EQ.1 ) THEN
         CALL DLASCL( 'G', 0, 0, SMLNUM, BNRM, SCLLEN, NRHS, B, LDB,
     $                INFO )
      ELSE IF( IBSCL.EQ.2 ) THEN
         CALL DLASCL( 'G', 0, 0, BIGNUM, BNRM, SCLLEN, NRHS, B, LDB,
     $                INFO )
      END IF
*
   50 CONTINUE
      WORK( 1 ) = DBLE( WSIZE )
*
      RETURN
*
*     End of DGELS
*
      END
*> \brief <b> DGELSD computes the minimum-norm solution to a linear least squares problem for GE matrices</b>
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGELSD + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgelsd.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgelsd.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgelsd.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGELSD( M, N, NRHS, A, LDA, B, LDB, S, RCOND, RANK,
*                          WORK, LWORK, IWORK, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, LDA, LDB, LWORK, M, N, NRHS, RANK
*       DOUBLE PRECISION   RCOND
*       ..
*       .. Array Arguments ..
*       INTEGER            IWORK( * )
*       DOUBLE PRECISION   A( LDA, * ), B( LDB, * ), S( * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGELSD computes the minimum-norm solution to a real linear least
*> squares problem:
*>     minimize 2-norm(| b - A*x |)
*> using the singular value decomposition (SVD) of A. A is an M-by-N
*> matrix which may be rank-deficient.
*>
*> Several right hand side vectors b and solution vectors x can be
*> handled in a single call; they are stored as the columns of the
*> M-by-NRHS right hand side matrix B and the N-by-NRHS solution
*> matrix X.
*>
*> The problem is solved in three steps:
*> (1) Reduce the coefficient matrix A to bidiagonal form with
*>     Householder transformations, reducing the original problem
*>     into a "bidiagonal least squares problem" (BLS)
*> (2) Solve the BLS using a divide and conquer approach.
*> (3) Apply back all the Householder transformations to solve
*>     the original least squares problem.
*>
*> The effective rank of A is determined by treating as zero those
*> singular values which are less than RCOND times the largest singular
*> value.
*>
*> The divide and conquer algorithm makes very mild assumptions about
*> floating point arithmetic. It will work on machines with a guard
*> digit in add/subtract, or on those binary machines without guard
*> digits which subtract like the Cray X-MP, Cray Y-MP, Cray C-90, or
*> Cray-2. It could conceivably fail on hexadecimal or decimal machines
*> without guard digits, but we know of none.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of A. M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of A. N >= 0.
*> \endverbatim
*>
*> \param[in] NRHS
*> \verbatim
*>          NRHS is INTEGER
*>          The number of right hand sides, i.e., the number of columns
*>          of the matrices B and X. NRHS >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the M-by-N matrix A.
*>          On exit, A has been destroyed.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,M).
*> \endverbatim
*>
*> \param[in,out] B
*> \verbatim
*>          B is DOUBLE PRECISION array, dimension (LDB,NRHS)
*>          On entry, the M-by-NRHS right hand side matrix B.
*>          On exit, B is overwritten by the N-by-NRHS solution
*>          matrix X.  If m >= n and RANK = n, the residual
*>          sum-of-squares for the solution in the i-th column is given
*>          by the sum of squares of elements n+1:m in that column.
*> \endverbatim
*>
*> \param[in] LDB
*> \verbatim
*>          LDB is INTEGER
*>          The leading dimension of the array B. LDB >= max(1,max(M,N)).
*> \endverbatim
*>
*> \param[out] S
*> \verbatim
*>          S is DOUBLE PRECISION array, dimension (min(M,N))
*>          The singular values of A in decreasing order.
*>          The condition number of A in the 2-norm = S(1)/S(min(m,n)).
*> \endverbatim
*>
*> \param[in] RCOND
*> \verbatim
*>          RCOND is DOUBLE PRECISION
*>          RCOND is used to determine the effective rank of A.
*>          Singular values S(i) <= RCOND*S(1) are treated as zero.
*>          If RCOND < 0, machine precision is used instead.
*> \endverbatim
*>
*> \param[out] RANK
*> \verbatim
*>          RANK is INTEGER
*>          The effective rank of A, i.e., the number of singular values
*>          which are greater than RCOND*S(1).
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK))
*>          On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
*> \endverbatim
*>
*> \param[in] LWORK
*> \verbatim
*>          LWORK is INTEGER
*>          The dimension of the array WORK. LWORK must be at least 1.
*>          The exact minimum amount of workspace needed depends on M,
*>          N and NRHS. As long as LWORK is at least
*>              12*N + 2*N*SMLSIZ + 8*N*NLVL + N*NRHS + (SMLSIZ+1)**2,
*>          if M is greater than or equal to N or
*>              12*M + 2*M*SMLSIZ + 8*M*NLVL + M*NRHS + (SMLSIZ+1)**2,
*>          if M is less than N, the code will execute correctly.
*>          SMLSIZ is returned by ILAENV and is equal to the maximum
*>          size of the subproblems at the bottom of the computation
*>          tree (usually about 25), and
*>             NLVL = MAX( 0, INT( LOG_2( MIN( M,N )/(SMLSIZ+1) ) ) + 1 )
*>          For good performance, LWORK should generally be larger.
*>
*>          If LWORK = -1, then a workspace query is assumed; the routine
*>          only calculates the optimal size of the WORK array, returns
*>          this value as the first entry of the WORK array, and no error
*>          message related to LWORK is issued by XERBLA.
*> \endverbatim
*>
*> \param[out] IWORK
*> \verbatim
*>          IWORK is INTEGER array, dimension (MAX(1,LIWORK))
*>          LIWORK >= max(1, 3 * MINMN * NLVL + 11 * MINMN),
*>          where MINMN = MIN( M,N ).
*>          On exit, if INFO = 0, IWORK(1) returns the minimum LIWORK.
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value.
*>          > 0:  the algorithm for computing the SVD failed to converge;
*>                if INFO = i, i off-diagonal elements of an intermediate
*>                bidiagonal form did not converge to zero.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date June 2017
*
*> \ingroup doubleGEsolve
*
*> \par Contributors:
*  ==================
*>
*>     Ming Gu and Ren-Cang Li, Computer Science Division, University of
*>       California at Berkeley, USA \n
*>     Osni Marques, LBNL/NERSC, USA \n
*
*  =====================================================================
      SUBROUTINE DGELSD( M, N, NRHS, A, LDA, B, LDB, S, RCOND, RANK,
     $                   WORK, LWORK, IWORK, INFO )
*
*  -- LAPACK driver routine (version 3.7.1) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     June 2017
*
*     .. Scalar Arguments ..
      INTEGER            INFO, LDA, LDB, LWORK, M, N, NRHS, RANK
      DOUBLE PRECISION   RCOND
*     ..
*     .. Array Arguments ..
      INTEGER            IWORK( * )
      DOUBLE PRECISION   A( LDA, * ), B( LDB, * ), S( * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ZERO, ONE, TWO
      PARAMETER          ( ZERO = 0.0D0, ONE = 1.0D0, TWO = 2.0D0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            LQUERY
      INTEGER            IASCL, IBSCL, IE, IL, ITAU, ITAUP, ITAUQ,
     $                   LDWORK, LIWORK, MAXMN, MAXWRK, MINMN, MINWRK,
     $                   MM, MNTHR, NLVL, NWORK, SMLSIZ, WLALSD
      DOUBLE PRECISION   ANRM, BIGNUM, BNRM, EPS, SFMIN, SMLNUM
*     ..
*     .. External Subroutines ..
      EXTERNAL           DGEBRD, DGELQF, DGEQRF, DLABAD, DLACPY, DLALSD,
     $                   DLASCL, DLASET, DORMBR, DORMLQ, DORMQR, XERBLA
*     ..
*     .. External Functions ..
      INTEGER            ILAENV
      DOUBLE PRECISION   DLAMCH, DLANGE
      EXTERNAL           ILAENV, DLAMCH, DLANGE
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          DBLE, INT, LOG, MAX, MIN
*     ..
*     .. Executable Statements ..
*
*     Test the input arguments.
*
      INFO = 0
      MINMN = MIN( M, N )
      MAXMN = MAX( M, N )
      MNTHR = ILAENV( 6, 'DGELSD', ' ', M, N, NRHS, -1 )
      LQUERY = ( LWORK.EQ.-1 )
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( NRHS.LT.0 ) THEN
         INFO = -3
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -5
      ELSE IF( LDB.LT.MAX( 1, MAXMN ) ) THEN
         INFO = -7
      END IF
*
      SMLSIZ = ILAENV( 9, 'DGELSD', ' ', 0, 0, 0, 0 )
*
*     Compute workspace.
*     (Note: Comments in the code beginning "Workspace:" describe the
*     minimal amount of workspace needed at that point in the code,
*     as well as the preferred amount for good performance.
*     NB refers to the optimal block size for the immediately
*     following subroutine, as returned by ILAENV.)
*
      MINWRK = 1
      LIWORK = 1
      MINMN = MAX( 1, MINMN )
      NLVL = MAX( INT( LOG( DBLE( MINMN ) / DBLE( SMLSIZ+1 ) ) /
     $       LOG( TWO ) ) + 1, 0 )
*
      IF( INFO.EQ.0 ) THEN
         MAXWRK = 0
         LIWORK = 3*MINMN*NLVL + 11*MINMN
         MM = M
         IF( M.GE.N .AND. M.GE.MNTHR ) THEN
*
*           Path 1a - overdetermined, with many more rows than columns.
*
            MM = N
            MAXWRK = MAX( MAXWRK, N+N*ILAENV( 1, 'DGEQRF', ' ', M, N,
     $               -1, -1 ) )
            MAXWRK = MAX( MAXWRK, N+NRHS*
     $               ILAENV( 1, 'DORMQR', 'LT', M, NRHS, N, -1 ) )
         END IF
         IF( M.GE.N ) THEN
*
*           Path 1 - overdetermined or exactly determined.
*
            MAXWRK = MAX( MAXWRK, 3*N+( MM+N )*
     $               ILAENV( 1, 'DGEBRD', ' ', MM, N, -1, -1 ) )
            MAXWRK = MAX( MAXWRK, 3*N+NRHS*
     $               ILAENV( 1, 'DORMBR', 'QLT', MM, NRHS, N, -1 ) )
            MAXWRK = MAX( MAXWRK, 3*N+( N-1 )*
     $               ILAENV( 1, 'DORMBR', 'PLN', N, NRHS, N, -1 ) )
            WLALSD = 9*N+2*N*SMLSIZ+8*N*NLVL+N*NRHS+(SMLSIZ+1)**2
            MAXWRK = MAX( MAXWRK, 3*N+WLALSD )
            MINWRK = MAX( 3*N+MM, 3*N+NRHS, 3*N+WLALSD )
         END IF
         IF( N.GT.M ) THEN
            WLALSD = 9*M+2*M*SMLSIZ+8*M*NLVL+M*NRHS+(SMLSIZ+1)**2
            IF( N.GE.MNTHR ) THEN
*
*              Path 2a - underdetermined, with many more columns
*              than rows.
*
               MAXWRK = M + M*ILAENV( 1, 'DGELQF', ' ', M, N, -1, -1 )
               MAXWRK = MAX( MAXWRK, M*M+4*M+2*M*
     $                  ILAENV( 1, 'DGEBRD', ' ', M, M, -1, -1 ) )
               MAXWRK = MAX( MAXWRK, M*M+4*M+NRHS*
     $                  ILAENV( 1, 'DORMBR', 'QLT', M, NRHS, M, -1 ) )
               MAXWRK = MAX( MAXWRK, M*M+4*M+( M-1 )*
     $                  ILAENV( 1, 'DORMBR', 'PLN', M, NRHS, M, -1 ) )
               IF( NRHS.GT.1 ) THEN
                  MAXWRK = MAX( MAXWRK, M*M+M+M*NRHS )
               ELSE
                  MAXWRK = MAX( MAXWRK, M*M+2*M )
               END IF
               MAXWRK = MAX( MAXWRK, M+NRHS*
     $                  ILAENV( 1, 'DORMLQ', 'LT', N, NRHS, M, -1 ) )
               MAXWRK = MAX( MAXWRK, M*M+4*M+WLALSD )
!     XXX: Ensure the Path 2a case below is triggered.  The workspace
!     calculation should use queries for all routines eventually.
               MAXWRK = MAX( MAXWRK,
     $              4*M+M*M+MAX( M, 2*M-4, NRHS, N-3*M ) )
            ELSE
*
*              Path 2 - remaining underdetermined cases.
*
               MAXWRK = 3*M + ( N+M )*ILAENV( 1, 'DGEBRD', ' ', M, N,
     $                  -1, -1 )
               MAXWRK = MAX( MAXWRK, 3*M+NRHS*
     $                  ILAENV( 1, 'DORMBR', 'QLT', M, NRHS, N, -1 ) )
               MAXWRK = MAX( MAXWRK, 3*M+M*
     $                  ILAENV( 1, 'DORMBR', 'PLN', N, NRHS, M, -1 ) )
               MAXWRK = MAX( MAXWRK, 3*M+WLALSD )
            END IF
            MINWRK = MAX( 3*M+NRHS, 3*M+M, 3*M+WLALSD )
         END IF
         MINWRK = MIN( MINWRK, MAXWRK )
         WORK( 1 ) = MAXWRK
         IWORK( 1 ) = LIWORK

         IF( LWORK.LT.MINWRK .AND. .NOT.LQUERY ) THEN
            INFO = -12
         END IF
      END IF
*
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGELSD', -INFO )
         RETURN
      ELSE IF( LQUERY ) THEN
         GO TO 10
      END IF
*
*     Quick return if possible.
*
      IF( M.EQ.0 .OR. N.EQ.0 ) THEN
         RANK = 0
         RETURN
      END IF
*
*     Get machine parameters.
*
      EPS = DLAMCH( 'P' )
      SFMIN = DLAMCH( 'S' )
      SMLNUM = SFMIN / EPS
      BIGNUM = ONE / SMLNUM
      CALL DLABAD( SMLNUM, BIGNUM )
*
*     Scale A if max entry outside range [SMLNUM,BIGNUM].
*
      ANRM = DLANGE( 'M', M, N, A, LDA, WORK )
      IASCL = 0
      IF( ANRM.GT.ZERO .AND. ANRM.LT.SMLNUM ) THEN
*
*        Scale matrix norm up to SMLNUM.
*
         CALL DLASCL( 'G', 0, 0, ANRM, SMLNUM, M, N, A, LDA, INFO )
         IASCL = 1
      ELSE IF( ANRM.GT.BIGNUM ) THEN
*
*        Scale matrix norm down to BIGNUM.
*
         CALL DLASCL( 'G', 0, 0, ANRM, BIGNUM, M, N, A, LDA, INFO )
         IASCL = 2
      ELSE IF( ANRM.EQ.ZERO ) THEN
*
*        Matrix all zero. Return zero solution.
*
         CALL DLASET( 'F', MAX( M, N ), NRHS, ZERO, ZERO, B, LDB )
         CALL DLASET( 'F', MINMN, 1, ZERO, ZERO, S, 1 )
         RANK = 0
         GO TO 10
      END IF
*
*     Scale B if max entry outside range [SMLNUM,BIGNUM].
*
      BNRM = DLANGE( 'M', M, NRHS, B, LDB, WORK )
      IBSCL = 0
      IF( BNRM.GT.ZERO .AND. BNRM.LT.SMLNUM ) THEN
*
*        Scale matrix norm up to SMLNUM.
*
         CALL DLASCL( 'G', 0, 0, BNRM, SMLNUM, M, NRHS, B, LDB, INFO )
         IBSCL = 1
      ELSE IF( BNRM.GT.BIGNUM ) THEN
*
*        Scale matrix norm down to BIGNUM.
*
         CALL DLASCL( 'G', 0, 0, BNRM, BIGNUM, M, NRHS, B, LDB, INFO )
         IBSCL = 2
      END IF
*
*     If M < N make sure certain entries of B are zero.
*
      IF( M.LT.N )
     $   CALL DLASET( 'F', N-M, NRHS, ZERO, ZERO, B( M+1, 1 ), LDB )
*
*     Overdetermined case.
*
      IF( M.GE.N ) THEN
*
*        Path 1 - overdetermined or exactly determined.
*
         MM = M
         IF( M.GE.MNTHR ) THEN
*
*           Path 1a - overdetermined, with many more rows than columns.
*
            MM = N
            ITAU = 1
            NWORK = ITAU + N
*
*           Compute A=Q*R.
*           (Workspace: need 2*N, prefer N+N*NB)
*
            CALL DGEQRF( M, N, A, LDA, WORK( ITAU ), WORK( NWORK ),
     $                   LWORK-NWORK+1, INFO )
*
*           Multiply B by transpose(Q).
*           (Workspace: need N+NRHS, prefer N+NRHS*NB)
*
            CALL DORMQR( 'L', 'T', M, NRHS, N, A, LDA, WORK( ITAU ), B,
     $                   LDB, WORK( NWORK ), LWORK-NWORK+1, INFO )
*
*           Zero out below R.
*
            IF( N.GT.1 ) THEN
               CALL DLASET( 'L', N-1, N-1, ZERO, ZERO, A( 2, 1 ), LDA )
            END IF
         END IF
*
         IE = 1
         ITAUQ = IE + N
         ITAUP = ITAUQ + N
         NWORK = ITAUP + N
*
*        Bidiagonalize R in A.
*        (Workspace: need 3*N+MM, prefer 3*N+(MM+N)*NB)
*
         CALL DGEBRD( MM, N, A, LDA, S, WORK( IE ), WORK( ITAUQ ),
     $                WORK( ITAUP ), WORK( NWORK ), LWORK-NWORK+1,
     $                INFO )
*
*        Multiply B by transpose of left bidiagonalizing vectors of R.
*        (Workspace: need 3*N+NRHS, prefer 3*N+NRHS*NB)
*
         CALL DORMBR( 'Q', 'L', 'T', MM, NRHS, N, A, LDA, WORK( ITAUQ ),
     $                B, LDB, WORK( NWORK ), LWORK-NWORK+1, INFO )
*
*        Solve the bidiagonal least squares problem.
*
         CALL DLALSD( 'U', SMLSIZ, N, NRHS, S, WORK( IE ), B, LDB,
     $                RCOND, RANK, WORK( NWORK ), IWORK, INFO )
         IF( INFO.NE.0 ) THEN
            GO TO 10
         END IF
*
*        Multiply B by right bidiagonalizing vectors of R.
*
         CALL DORMBR( 'P', 'L', 'N', N, NRHS, N, A, LDA, WORK( ITAUP ),
     $                B, LDB, WORK( NWORK ), LWORK-NWORK+1, INFO )
*
      ELSE IF( N.GE.MNTHR .AND. LWORK.GE.4*M+M*M+
     $         MAX( M, 2*M-4, NRHS, N-3*M, WLALSD ) ) THEN
*
*        Path 2a - underdetermined, with many more columns than rows
*        and sufficient workspace for an efficient algorithm.
*
         LDWORK = M
         IF( LWORK.GE.MAX( 4*M+M*LDA+MAX( M, 2*M-4, NRHS, N-3*M ),
     $       M*LDA+M+M*NRHS, 4*M+M*LDA+WLALSD ) )LDWORK = LDA
         ITAU = 1
         NWORK = M + 1
*
*        Compute A=L*Q.
*        (Workspace: need 2*M, prefer M+M*NB)
*
         CALL DGELQF( M, N, A, LDA, WORK( ITAU ), WORK( NWORK ),
     $                LWORK-NWORK+1, INFO )
         IL = NWORK
*
*        Copy L to WORK(IL), zeroing out above its diagonal.
*
         CALL DLACPY( 'L', M, M, A, LDA, WORK( IL ), LDWORK )
         CALL DLASET( 'U', M-1, M-1, ZERO, ZERO, WORK( IL+LDWORK ),
     $                LDWORK )
         IE = IL + LDWORK*M
         ITAUQ = IE + M
         ITAUP = ITAUQ + M
         NWORK = ITAUP + M
*
*        Bidiagonalize L in WORK(IL).
*        (Workspace: need M*M+5*M, prefer M*M+4*M+2*M*NB)
*
         CALL DGEBRD( M, M, WORK( IL ), LDWORK, S, WORK( IE ),
     $                WORK( ITAUQ ), WORK( ITAUP ), WORK( NWORK ),
     $                LWORK-NWORK+1, INFO )
*
*        Multiply B by transpose of left bidiagonalizing vectors of L.
*        (Workspace: need M*M+4*M+NRHS, prefer M*M+4*M+NRHS*NB)
*
         CALL DORMBR( 'Q', 'L', 'T', M, NRHS, M, WORK( IL ), LDWORK,
     $                WORK( ITAUQ ), B, LDB, WORK( NWORK ),
     $                LWORK-NWORK+1, INFO )
*
*        Solve the bidiagonal least squares problem.
*
         CALL DLALSD( 'U', SMLSIZ, M, NRHS, S, WORK( IE ), B, LDB,
     $                RCOND, RANK, WORK( NWORK ), IWORK, INFO )
         IF( INFO.NE.0 ) THEN
            GO TO 10
         END IF
*
*        Multiply B by right bidiagonalizing vectors of L.
*
         CALL DORMBR( 'P', 'L', 'N', M, NRHS, M, WORK( IL ), LDWORK,
     $                WORK( ITAUP ), B, LDB, WORK( NWORK ),
     $                LWORK-NWORK+1, INFO )
*
*        Zero out below first M rows of B.
*
         CALL DLASET( 'F', N-M, NRHS, ZERO, ZERO, B( M+1, 1 ), LDB )
         NWORK = ITAU + M
*
*        Multiply transpose(Q) by B.
*        (Workspace: need M+NRHS, prefer M+NRHS*NB)
*
         CALL DORMLQ( 'L', 'T', N, NRHS, M, A, LDA, WORK( ITAU ), B,
     $                LDB, WORK( NWORK ), LWORK-NWORK+1, INFO )
*
      ELSE
*
*        Path 2 - remaining underdetermined cases.
*
         IE = 1
         ITAUQ = IE + M
         ITAUP = ITAUQ + M
         NWORK = ITAUP + M
*
*        Bidiagonalize A.
*        (Workspace: need 3*M+N, prefer 3*M+(M+N)*NB)
*
         CALL DGEBRD( M, N, A, LDA, S, WORK( IE ), WORK( ITAUQ ),
     $                WORK( ITAUP ), WORK( NWORK ), LWORK-NWORK+1,
     $                INFO )
*
*        Multiply B by transpose of left bidiagonalizing vectors.
*        (Workspace: need 3*M+NRHS, prefer 3*M+NRHS*NB)
*
         CALL DORMBR( 'Q', 'L', 'T', M, NRHS, N, A, LDA, WORK( ITAUQ ),
     $                B, LDB, WORK( NWORK ), LWORK-NWORK+1, INFO )
*
*        Solve the bidiagonal least squares problem.
*
         CALL DLALSD( 'L', SMLSIZ, M, NRHS, S, WORK( IE ), B, LDB,
     $                RCOND, RANK, WORK( NWORK ), IWORK, INFO )
         IF( INFO.NE.0 ) THEN
            GO TO 10
         END IF
*
*        Multiply B by right bidiagonalizing vectors of A.
*
         CALL DORMBR( 'P', 'L', 'N', N, NRHS, M, A, LDA, WORK( ITAUP ),
     $                B, LDB, WORK( NWORK ), LWORK-NWORK+1, INFO )
*
      END IF
*
*     Undo scaling.
*
      IF( IASCL.EQ.1 ) THEN
         CALL DLASCL( 'G', 0, 0, ANRM, SMLNUM, N, NRHS, B, LDB, INFO )
         CALL DLASCL( 'G', 0, 0, SMLNUM, ANRM, MINMN, 1, S, MINMN,
     $                INFO )
      ELSE IF( IASCL.EQ.2 ) THEN
         CALL DLASCL( 'G', 0, 0, ANRM, BIGNUM, N, NRHS, B, LDB, INFO )
         CALL DLASCL( 'G', 0, 0, BIGNUM, ANRM, MINMN, 1, S, MINMN,
     $                INFO )
      END IF
      IF( IBSCL.EQ.1 ) THEN
         CALL DLASCL( 'G', 0, 0, SMLNUM, BNRM, N, NRHS, B, LDB, INFO )
      ELSE IF( IBSCL.EQ.2 ) THEN
         CALL DLASCL( 'G', 0, 0, BIGNUM, BNRM, N, NRHS, B, LDB, INFO )
      END IF
*
   10 CONTINUE
      WORK( 1 ) = MAXWRK
      IWORK( 1 ) = LIWORK
      RETURN
*
*     End of DGELSD
*
      END
*> \brief <b> DGELSS solves overdetermined or underdetermined systems for GE matrices</b>
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGELSS + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgelss.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgelss.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgelss.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGELSS( M, N, NRHS, A, LDA, B, LDB, S, RCOND, RANK,
*                          WORK, LWORK, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, LDA, LDB, LWORK, M, N, NRHS, RANK
*       DOUBLE PRECISION   RCOND
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   A( LDA, * ), B( LDB, * ), S( * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGELSS computes the minimum norm solution to a real linear least
*> squares problem:
*>
*> Minimize 2-norm(| b - A*x |).
*>
*> using the singular value decomposition (SVD) of A. A is an M-by-N
*> matrix which may be rank-deficient.
*>
*> Several right hand side vectors b and solution vectors x can be
*> handled in a single call; they are stored as the columns of the
*> M-by-NRHS right hand side matrix B and the N-by-NRHS solution matrix
*> X.
*>
*> The effective rank of A is determined by treating as zero those
*> singular values which are less than RCOND times the largest singular
*> value.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A. M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A. N >= 0.
*> \endverbatim
*>
*> \param[in] NRHS
*> \verbatim
*>          NRHS is INTEGER
*>          The number of right hand sides, i.e., the number of columns
*>          of the matrices B and X. NRHS >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the M-by-N matrix A.
*>          On exit, the first min(m,n) rows of A are overwritten with
*>          its right singular vectors, stored rowwise.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,M).
*> \endverbatim
*>
*> \param[in,out] B
*> \verbatim
*>          B is DOUBLE PRECISION array, dimension (LDB,NRHS)
*>          On entry, the M-by-NRHS right hand side matrix B.
*>          On exit, B is overwritten by the N-by-NRHS solution
*>          matrix X.  If m >= n and RANK = n, the residual
*>          sum-of-squares for the solution in the i-th column is given
*>          by the sum of squares of elements n+1:m in that column.
*> \endverbatim
*>
*> \param[in] LDB
*> \verbatim
*>          LDB is INTEGER
*>          The leading dimension of the array B. LDB >= max(1,max(M,N)).
*> \endverbatim
*>
*> \param[out] S
*> \verbatim
*>          S is DOUBLE PRECISION array, dimension (min(M,N))
*>          The singular values of A in decreasing order.
*>          The condition number of A in the 2-norm = S(1)/S(min(m,n)).
*> \endverbatim
*>
*> \param[in] RCOND
*> \verbatim
*>          RCOND is DOUBLE PRECISION
*>          RCOND is used to determine the effective rank of A.
*>          Singular values S(i) <= RCOND*S(1) are treated as zero.
*>          If RCOND < 0, machine precision is used instead.
*> \endverbatim
*>
*> \param[out] RANK
*> \verbatim
*>          RANK is INTEGER
*>          The effective rank of A, i.e., the number of singular values
*>          which are greater than RCOND*S(1).
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK))
*>          On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
*> \endverbatim
*>
*> \param[in] LWORK
*> \verbatim
*>          LWORK is INTEGER
*>          The dimension of the array WORK. LWORK >= 1, and also:
*>          LWORK >= 3*min(M,N) + max( 2*min(M,N), max(M,N), NRHS )
*>          For good performance, LWORK should generally be larger.
*>
*>          If LWORK = -1, then a workspace query is assumed; the routine
*>          only calculates the optimal size of the WORK array, returns
*>          this value as the first entry of the WORK array, and no error
*>          message related to LWORK is issued by XERBLA.
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value.
*>          > 0:  the algorithm for computing the SVD failed to converge;
*>                if INFO = i, i off-diagonal elements of an intermediate
*>                bidiagonal form did not converge to zero.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEsolve
*
*  =====================================================================
      SUBROUTINE DGELSS( M, N, NRHS, A, LDA, B, LDB, S, RCOND, RANK,
     $                   WORK, LWORK, INFO )
*
*  -- LAPACK driver routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER            INFO, LDA, LDB, LWORK, M, N, NRHS, RANK
      DOUBLE PRECISION   RCOND
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   A( LDA, * ), B( LDB, * ), S( * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ZERO, ONE
      PARAMETER          ( ZERO = 0.0D+0, ONE = 1.0D+0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            LQUERY
      INTEGER            BDSPAC, BL, CHUNK, I, IASCL, IBSCL, IE, IL,
     $                   ITAU, ITAUP, ITAUQ, IWORK, LDWORK, MAXMN,
     $                   MAXWRK, MINMN, MINWRK, MM, MNTHR
      INTEGER            LWORK_DGEQRF, LWORK_DORMQR, LWORK_DGEBRD,
     $                   LWORK_DORMBR, LWORK_DORGBR, LWORK_DORMLQ,
     $                   LWORK_DGELQF
      DOUBLE PRECISION   ANRM, BIGNUM, BNRM, EPS, SFMIN, SMLNUM, THR
*     ..
*     .. Local Arrays ..
      DOUBLE PRECISION   DUM( 1 )
*     ..
*     .. External Subroutines ..
      EXTERNAL           DBDSQR, DCOPY, DGEBRD, DGELQF, DGEMM, DGEMV,
     $                   DGEQRF, DLABAD, DLACPY, DLASCL, DLASET, DORGBR,
     $                   DORMBR, DORMLQ, DORMQR, DRSCL, XERBLA
*     ..
*     .. External Functions ..
      INTEGER            ILAENV
      DOUBLE PRECISION   DLAMCH, DLANGE
      EXTERNAL           ILAENV, DLAMCH, DLANGE
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, MIN
*     ..
*     .. Executable Statements ..
*
*     Test the input arguments
*
      INFO = 0
      MINMN = MIN( M, N )
      MAXMN = MAX( M, N )
      LQUERY = ( LWORK.EQ.-1 )
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( NRHS.LT.0 ) THEN
         INFO = -3
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -5
      ELSE IF( LDB.LT.MAX( 1, MAXMN ) ) THEN
         INFO = -7
      END IF
*
*     Compute workspace
*      (Note: Comments in the code beginning "Workspace:" describe the
*       minimal amount of workspace needed at that point in the code,
*       as well as the preferred amount for good performance.
*       NB refers to the optimal block size for the immediately
*       following subroutine, as returned by ILAENV.)
*
      IF( INFO.EQ.0 ) THEN
         MINWRK = 1
         MAXWRK = 1
         IF( MINMN.GT.0 ) THEN
            MM = M
            MNTHR = ILAENV( 6, 'DGELSS', ' ', M, N, NRHS, -1 )
            IF( M.GE.N .AND. M.GE.MNTHR ) THEN
*
*              Path 1a - overdetermined, with many more rows than
*                        columns
*
*              Compute space needed for DGEQRF
               CALL DGEQRF( M, N, A, LDA, DUM(1), DUM(1), -1, INFO )
               LWORK_DGEQRF=DUM(1)
*              Compute space needed for DORMQR
               CALL DORMQR( 'L', 'T', M, NRHS, N, A, LDA, DUM(1), B,
     $                   LDB, DUM(1), -1, INFO )
               LWORK_DORMQR=DUM(1)
               MM = N
               MAXWRK = MAX( MAXWRK, N + LWORK_DGEQRF )
               MAXWRK = MAX( MAXWRK, N + LWORK_DORMQR )
            END IF
            IF( M.GE.N ) THEN
*
*              Path 1 - overdetermined or exactly determined
*
*              Compute workspace needed for DBDSQR
*
               BDSPAC = MAX( 1, 5*N )
*              Compute space needed for DGEBRD
               CALL DGEBRD( MM, N, A, LDA, S, DUM(1), DUM(1),
     $                      DUM(1), DUM(1), -1, INFO )
               LWORK_DGEBRD=DUM(1)
*              Compute space needed for DORMBR
               CALL DORMBR( 'Q', 'L', 'T', MM, NRHS, N, A, LDA, DUM(1),
     $                B, LDB, DUM(1), -1, INFO )
               LWORK_DORMBR=DUM(1)
*              Compute space needed for DORGBR
               CALL DORGBR( 'P', N, N, N, A, LDA, DUM(1),
     $                   DUM(1), -1, INFO )
               LWORK_DORGBR=DUM(1)
*              Compute total workspace needed
               MAXWRK = MAX( MAXWRK, 3*N + LWORK_DGEBRD )
               MAXWRK = MAX( MAXWRK, 3*N + LWORK_DORMBR )
               MAXWRK = MAX( MAXWRK, 3*N + LWORK_DORGBR )
               MAXWRK = MAX( MAXWRK, BDSPAC )
               MAXWRK = MAX( MAXWRK, N*NRHS )
               MINWRK = MAX( 3*N + MM, 3*N + NRHS, BDSPAC )
               MAXWRK = MAX( MINWRK, MAXWRK )
            END IF
            IF( N.GT.M ) THEN
*
*              Compute workspace needed for DBDSQR
*
               BDSPAC = MAX( 1, 5*M )
               MINWRK = MAX( 3*M+NRHS, 3*M+N, BDSPAC )
               IF( N.GE.MNTHR ) THEN
*
*                 Path 2a - underdetermined, with many more columns
*                 than rows
*
*                 Compute space needed for DGELQF
                  CALL DGELQF( M, N, A, LDA, DUM(1), DUM(1),
     $                -1, INFO )
                  LWORK_DGELQF=DUM(1)
*                 Compute space needed for DGEBRD
                  CALL DGEBRD( M, M, A, LDA, S, DUM(1), DUM(1),
     $                      DUM(1), DUM(1), -1, INFO )
                  LWORK_DGEBRD=DUM(1)
*                 Compute space needed for DORMBR
                  CALL DORMBR( 'Q', 'L', 'T', M, NRHS, N, A, LDA,
     $                DUM(1), B, LDB, DUM(1), -1, INFO )
                  LWORK_DORMBR=DUM(1)
*                 Compute space needed for DORGBR
                  CALL DORGBR( 'P', M, M, M, A, LDA, DUM(1),
     $                   DUM(1), -1, INFO )
                  LWORK_DORGBR=DUM(1)
*                 Compute space needed for DORMLQ
                  CALL DORMLQ( 'L', 'T', N, NRHS, M, A, LDA, DUM(1),
     $                 B, LDB, DUM(1), -1, INFO )
                  LWORK_DORMLQ=DUM(1)
*                 Compute total workspace needed
                  MAXWRK = M + LWORK_DGELQF
                  MAXWRK = MAX( MAXWRK, M*M + 4*M + LWORK_DGEBRD )
                  MAXWRK = MAX( MAXWRK, M*M + 4*M + LWORK_DORMBR )
                  MAXWRK = MAX( MAXWRK, M*M + 4*M + LWORK_DORGBR )
                  MAXWRK = MAX( MAXWRK, M*M + M + BDSPAC )
                  IF( NRHS.GT.1 ) THEN
                     MAXWRK = MAX( MAXWRK, M*M + M + M*NRHS )
                  ELSE
                     MAXWRK = MAX( MAXWRK, M*M + 2*M )
                  END IF
                  MAXWRK = MAX( MAXWRK, M + LWORK_DORMLQ )
               ELSE
*
*                 Path 2 - underdetermined
*
*                 Compute space needed for DGEBRD
                  CALL DGEBRD( M, N, A, LDA, S, DUM(1), DUM(1),
     $                      DUM(1), DUM(1), -1, INFO )
                  LWORK_DGEBRD=DUM(1)
*                 Compute space needed for DORMBR
                  CALL DORMBR( 'Q', 'L', 'T', M, NRHS, M, A, LDA,
     $                DUM(1), B, LDB, DUM(1), -1, INFO )
                  LWORK_DORMBR=DUM(1)
*                 Compute space needed for DORGBR
                  CALL DORGBR( 'P', M, N, M, A, LDA, DUM(1),
     $                   DUM(1), -1, INFO )
                  LWORK_DORGBR=DUM(1)
                  MAXWRK = 3*M + LWORK_DGEBRD
                  MAXWRK = MAX( MAXWRK, 3*M + LWORK_DORMBR )
                  MAXWRK = MAX( MAXWRK, 3*M + LWORK_DORGBR )
                  MAXWRK = MAX( MAXWRK, BDSPAC )
                  MAXWRK = MAX( MAXWRK, N*NRHS )
               END IF
            END IF
            MAXWRK = MAX( MINWRK, MAXWRK )
         END IF
         WORK( 1 ) = MAXWRK
*
         IF( LWORK.LT.MINWRK .AND. .NOT.LQUERY )
     $      INFO = -12
      END IF
*
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGELSS', -INFO )
         RETURN
      ELSE IF( LQUERY ) THEN
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( M.EQ.0 .OR. N.EQ.0 ) THEN
         RANK = 0
         RETURN
      END IF
*
*     Get machine parameters
*
      EPS = DLAMCH( 'P' )
      SFMIN = DLAMCH( 'S' )
      SMLNUM = SFMIN / EPS
      BIGNUM = ONE / SMLNUM
      CALL DLABAD( SMLNUM, BIGNUM )
*
*     Scale A if max element outside range [SMLNUM,BIGNUM]
*
      ANRM = DLANGE( 'M', M, N, A, LDA, WORK )
      IASCL = 0
      IF( ANRM.GT.ZERO .AND. ANRM.LT.SMLNUM ) THEN
*
*        Scale matrix norm up to SMLNUM
*
         CALL DLASCL( 'G', 0, 0, ANRM, SMLNUM, M, N, A, LDA, INFO )
         IASCL = 1
      ELSE IF( ANRM.GT.BIGNUM ) THEN
*
*        Scale matrix norm down to BIGNUM
*
         CALL DLASCL( 'G', 0, 0, ANRM, BIGNUM, M, N, A, LDA, INFO )
         IASCL = 2
      ELSE IF( ANRM.EQ.ZERO ) THEN
*
*        Matrix all zero. Return zero solution.
*
         CALL DLASET( 'F', MAX( M, N ), NRHS, ZERO, ZERO, B, LDB )
         CALL DLASET( 'F', MINMN, 1, ZERO, ZERO, S, MINMN )
         RANK = 0
         GO TO 70
      END IF
*
*     Scale B if max element outside range [SMLNUM,BIGNUM]
*
      BNRM = DLANGE( 'M', M, NRHS, B, LDB, WORK )
      IBSCL = 0
      IF( BNRM.GT.ZERO .AND. BNRM.LT.SMLNUM ) THEN
*
*        Scale matrix norm up to SMLNUM
*
         CALL DLASCL( 'G', 0, 0, BNRM, SMLNUM, M, NRHS, B, LDB, INFO )
         IBSCL = 1
      ELSE IF( BNRM.GT.BIGNUM ) THEN
*
*        Scale matrix norm down to BIGNUM
*
         CALL DLASCL( 'G', 0, 0, BNRM, BIGNUM, M, NRHS, B, LDB, INFO )
         IBSCL = 2
      END IF
*
*     Overdetermined case
*
      IF( M.GE.N ) THEN
*
*        Path 1 - overdetermined or exactly determined
*
         MM = M
         IF( M.GE.MNTHR ) THEN
*
*           Path 1a - overdetermined, with many more rows than columns
*
            MM = N
            ITAU = 1
            IWORK = ITAU + N
*
*           Compute A=Q*R
*           (Workspace: need 2*N, prefer N+N*NB)
*
            CALL DGEQRF( M, N, A, LDA, WORK( ITAU ), WORK( IWORK ),
     $                   LWORK-IWORK+1, INFO )
*
*           Multiply B by transpose(Q)
*           (Workspace: need N+NRHS, prefer N+NRHS*NB)
*
            CALL DORMQR( 'L', 'T', M, NRHS, N, A, LDA, WORK( ITAU ), B,
     $                   LDB, WORK( IWORK ), LWORK-IWORK+1, INFO )
*
*           Zero out below R
*
            IF( N.GT.1 )
     $         CALL DLASET( 'L', N-1, N-1, ZERO, ZERO, A( 2, 1 ), LDA )
         END IF
*
         IE = 1
         ITAUQ = IE + N
         ITAUP = ITAUQ + N
         IWORK = ITAUP + N
*
*        Bidiagonalize R in A
*        (Workspace: need 3*N+MM, prefer 3*N+(MM+N)*NB)
*
         CALL DGEBRD( MM, N, A, LDA, S, WORK( IE ), WORK( ITAUQ ),
     $                WORK( ITAUP ), WORK( IWORK ), LWORK-IWORK+1,
     $                INFO )
*
*        Multiply B by transpose of left bidiagonalizing vectors of R
*        (Workspace: need 3*N+NRHS, prefer 3*N+NRHS*NB)
*
         CALL DORMBR( 'Q', 'L', 'T', MM, NRHS, N, A, LDA, WORK( ITAUQ ),
     $                B, LDB, WORK( IWORK ), LWORK-IWORK+1, INFO )
*
*        Generate right bidiagonalizing vectors of R in A
*        (Workspace: need 4*N-1, prefer 3*N+(N-1)*NB)
*
         CALL DORGBR( 'P', N, N, N, A, LDA, WORK( ITAUP ),
     $                WORK( IWORK ), LWORK-IWORK+1, INFO )
         IWORK = IE + N
*
*        Perform bidiagonal QR iteration
*          multiply B by transpose of left singular vectors
*          compute right singular vectors in A
*        (Workspace: need BDSPAC)
*
         CALL DBDSQR( 'U', N, N, 0, NRHS, S, WORK( IE ), A, LDA, DUM,
     $                1, B, LDB, WORK( IWORK ), INFO )
         IF( INFO.NE.0 )
     $      GO TO 70
*
*        Multiply B by reciprocals of singular values
*
         THR = MAX( RCOND*S( 1 ), SFMIN )
         IF( RCOND.LT.ZERO )
     $      THR = MAX( EPS*S( 1 ), SFMIN )
         RANK = 0
         DO 10 I = 1, N
            IF( S( I ).GT.THR ) THEN
               CALL DRSCL( NRHS, S( I ), B( I, 1 ), LDB )
               RANK = RANK + 1
            ELSE
               CALL DLASET( 'F', 1, NRHS, ZERO, ZERO, B( I, 1 ), LDB )
            END IF
   10    CONTINUE
*
*        Multiply B by right singular vectors
*        (Workspace: need N, prefer N*NRHS)
*
         IF( LWORK.GE.LDB*NRHS .AND. NRHS.GT.1 ) THEN
            CALL DGEMM( 'T', 'N', N, NRHS, N, ONE, A, LDA, B, LDB, ZERO,
     $                  WORK, LDB )
            CALL DLACPY( 'G', N, NRHS, WORK, LDB, B, LDB )
         ELSE IF( NRHS.GT.1 ) THEN
            CHUNK = LWORK / N
            DO 20 I = 1, NRHS, CHUNK
               BL = MIN( NRHS-I+1, CHUNK )
               CALL DGEMM( 'T', 'N', N, BL, N, ONE, A, LDA, B( 1, I ),
     $                     LDB, ZERO, WORK, N )
               CALL DLACPY( 'G', N, BL, WORK, N, B( 1, I ), LDB )
   20       CONTINUE
         ELSE
            CALL DGEMV( 'T', N, N, ONE, A, LDA, B, 1, ZERO, WORK, 1 )
            CALL DCOPY( N, WORK, 1, B, 1 )
         END IF
*
      ELSE IF( N.GE.MNTHR .AND. LWORK.GE.4*M+M*M+
     $         MAX( M, 2*M-4, NRHS, N-3*M ) ) THEN
*
*        Path 2a - underdetermined, with many more columns than rows
*        and sufficient workspace for an efficient algorithm
*
         LDWORK = M
         IF( LWORK.GE.MAX( 4*M+M*LDA+MAX( M, 2*M-4, NRHS, N-3*M ),
     $       M*LDA+M+M*NRHS ) )LDWORK = LDA
         ITAU = 1
         IWORK = M + 1
*
*        Compute A=L*Q
*        (Workspace: need 2*M, prefer M+M*NB)
*
         CALL DGELQF( M, N, A, LDA, WORK( ITAU ), WORK( IWORK ),
     $                LWORK-IWORK+1, INFO )
         IL = IWORK
*
*        Copy L to WORK(IL), zeroing out above it
*
         CALL DLACPY( 'L', M, M, A, LDA, WORK( IL ), LDWORK )
         CALL DLASET( 'U', M-1, M-1, ZERO, ZERO, WORK( IL+LDWORK ),
     $                LDWORK )
         IE = IL + LDWORK*M
         ITAUQ = IE + M
         ITAUP = ITAUQ + M
         IWORK = ITAUP + M
*
*        Bidiagonalize L in WORK(IL)
*        (Workspace: need M*M+5*M, prefer M*M+4*M+2*M*NB)
*
         CALL DGEBRD( M, M, WORK( IL ), LDWORK, S, WORK( IE ),
     $                WORK( ITAUQ ), WORK( ITAUP ), WORK( IWORK ),
     $                LWORK-IWORK+1, INFO )
*
*        Multiply B by transpose of left bidiagonalizing vectors of L
*        (Workspace: need M*M+4*M+NRHS, prefer M*M+4*M+NRHS*NB)
*
         CALL DORMBR( 'Q', 'L', 'T', M, NRHS, M, WORK( IL ), LDWORK,
     $                WORK( ITAUQ ), B, LDB, WORK( IWORK ),
     $                LWORK-IWORK+1, INFO )
*
*        Generate right bidiagonalizing vectors of R in WORK(IL)
*        (Workspace: need M*M+5*M-1, prefer M*M+4*M+(M-1)*NB)
*
         CALL DORGBR( 'P', M, M, M, WORK( IL ), LDWORK, WORK( ITAUP ),
     $                WORK( IWORK ), LWORK-IWORK+1, INFO )
         IWORK = IE + M
*
*        Perform bidiagonal QR iteration,
*           computing right singular vectors of L in WORK(IL) and
*           multiplying B by transpose of left singular vectors
*        (Workspace: need M*M+M+BDSPAC)
*
         CALL DBDSQR( 'U', M, M, 0, NRHS, S, WORK( IE ), WORK( IL ),
     $                LDWORK, A, LDA, B, LDB, WORK( IWORK ), INFO )
         IF( INFO.NE.0 )
     $      GO TO 70
*
*        Multiply B by reciprocals of singular values
*
         THR = MAX( RCOND*S( 1 ), SFMIN )
         IF( RCOND.LT.ZERO )
     $      THR = MAX( EPS*S( 1 ), SFMIN )
         RANK = 0
         DO 30 I = 1, M
            IF( S( I ).GT.THR ) THEN
               CALL DRSCL( NRHS, S( I ), B( I, 1 ), LDB )
               RANK = RANK + 1
            ELSE
               CALL DLASET( 'F', 1, NRHS, ZERO, ZERO, B( I, 1 ), LDB )
            END IF
   30    CONTINUE
         IWORK = IE
*
*        Multiply B by right singular vectors of L in WORK(IL)
*        (Workspace: need M*M+2*M, prefer M*M+M+M*NRHS)
*
         IF( LWORK.GE.LDB*NRHS+IWORK-1 .AND. NRHS.GT.1 ) THEN
            CALL DGEMM( 'T', 'N', M, NRHS, M, ONE, WORK( IL ), LDWORK,
     $                  B, LDB, ZERO, WORK( IWORK ), LDB )
            CALL DLACPY( 'G', M, NRHS, WORK( IWORK ), LDB, B, LDB )
         ELSE IF( NRHS.GT.1 ) THEN
            CHUNK = ( LWORK-IWORK+1 ) / M
            DO 40 I = 1, NRHS, CHUNK
               BL = MIN( NRHS-I+1, CHUNK )
               CALL DGEMM( 'T', 'N', M, BL, M, ONE, WORK( IL ), LDWORK,
     $                     B( 1, I ), LDB, ZERO, WORK( IWORK ), M )
               CALL DLACPY( 'G', M, BL, WORK( IWORK ), M, B( 1, I ),
     $                      LDB )
   40       CONTINUE
         ELSE
            CALL DGEMV( 'T', M, M, ONE, WORK( IL ), LDWORK, B( 1, 1 ),
     $                  1, ZERO, WORK( IWORK ), 1 )
            CALL DCOPY( M, WORK( IWORK ), 1, B( 1, 1 ), 1 )
         END IF
*
*        Zero out below first M rows of B
*
         CALL DLASET( 'F', N-M, NRHS, ZERO, ZERO, B( M+1, 1 ), LDB )
         IWORK = ITAU + M
*
*        Multiply transpose(Q) by B
*        (Workspace: need M+NRHS, prefer M+NRHS*NB)
*
         CALL DORMLQ( 'L', 'T', N, NRHS, M, A, LDA, WORK( ITAU ), B,
     $                LDB, WORK( IWORK ), LWORK-IWORK+1, INFO )
*
      ELSE
*
*        Path 2 - remaining underdetermined cases
*
         IE = 1
         ITAUQ = IE + M
         ITAUP = ITAUQ + M
         IWORK = ITAUP + M
*
*        Bidiagonalize A
*        (Workspace: need 3*M+N, prefer 3*M+(M+N)*NB)
*
         CALL DGEBRD( M, N, A, LDA, S, WORK( IE ), WORK( ITAUQ ),
     $                WORK( ITAUP ), WORK( IWORK ), LWORK-IWORK+1,
     $                INFO )
*
*        Multiply B by transpose of left bidiagonalizing vectors
*        (Workspace: need 3*M+NRHS, prefer 3*M+NRHS*NB)
*
         CALL DORMBR( 'Q', 'L', 'T', M, NRHS, N, A, LDA, WORK( ITAUQ ),
     $                B, LDB, WORK( IWORK ), LWORK-IWORK+1, INFO )
*
*        Generate right bidiagonalizing vectors in A
*        (Workspace: need 4*M, prefer 3*M+M*NB)
*
         CALL DORGBR( 'P', M, N, M, A, LDA, WORK( ITAUP ),
     $                WORK( IWORK ), LWORK-IWORK+1, INFO )
         IWORK = IE + M
*
*        Perform bidiagonal QR iteration,
*           computing right singular vectors of A in A and
*           multiplying B by transpose of left singular vectors
*        (Workspace: need BDSPAC)
*
         CALL DBDSQR( 'L', M, N, 0, NRHS, S, WORK( IE ), A, LDA, DUM,
     $                1, B, LDB, WORK( IWORK ), INFO )
         IF( INFO.NE.0 )
     $      GO TO 70
*
*        Multiply B by reciprocals of singular values
*
         THR = MAX( RCOND*S( 1 ), SFMIN )
         IF( RCOND.LT.ZERO )
     $      THR = MAX( EPS*S( 1 ), SFMIN )
         RANK = 0
         DO 50 I = 1, M
            IF( S( I ).GT.THR ) THEN
               CALL DRSCL( NRHS, S( I ), B( I, 1 ), LDB )
               RANK = RANK + 1
            ELSE
               CALL DLASET( 'F', 1, NRHS, ZERO, ZERO, B( I, 1 ), LDB )
            END IF
   50    CONTINUE
*
*        Multiply B by right singular vectors of A
*        (Workspace: need N, prefer N*NRHS)
*
         IF( LWORK.GE.LDB*NRHS .AND. NRHS.GT.1 ) THEN
            CALL DGEMM( 'T', 'N', N, NRHS, M, ONE, A, LDA, B, LDB, ZERO,
     $                  WORK, LDB )
            CALL DLACPY( 'F', N, NRHS, WORK, LDB, B, LDB )
         ELSE IF( NRHS.GT.1 ) THEN
            CHUNK = LWORK / N
            DO 60 I = 1, NRHS, CHUNK
               BL = MIN( NRHS-I+1, CHUNK )
               CALL DGEMM( 'T', 'N', N, BL, M, ONE, A, LDA, B( 1, I ),
     $                     LDB, ZERO, WORK, N )
               CALL DLACPY( 'F', N, BL, WORK, N, B( 1, I ), LDB )
   60       CONTINUE
         ELSE
            CALL DGEMV( 'T', M, N, ONE, A, LDA, B, 1, ZERO, WORK, 1 )
            CALL DCOPY( N, WORK, 1, B, 1 )
         END IF
      END IF
*
*     Undo scaling
*
      IF( IASCL.EQ.1 ) THEN
         CALL DLASCL( 'G', 0, 0, ANRM, SMLNUM, N, NRHS, B, LDB, INFO )
         CALL DLASCL( 'G', 0, 0, SMLNUM, ANRM, MINMN, 1, S, MINMN,
     $                INFO )
      ELSE IF( IASCL.EQ.2 ) THEN
         CALL DLASCL( 'G', 0, 0, ANRM, BIGNUM, N, NRHS, B, LDB, INFO )
         CALL DLASCL( 'G', 0, 0, BIGNUM, ANRM, MINMN, 1, S, MINMN,
     $                INFO )
      END IF
      IF( IBSCL.EQ.1 ) THEN
         CALL DLASCL( 'G', 0, 0, SMLNUM, BNRM, N, NRHS, B, LDB, INFO )
      ELSE IF( IBSCL.EQ.2 ) THEN
         CALL DLASCL( 'G', 0, 0, BIGNUM, BNRM, N, NRHS, B, LDB, INFO )
      END IF
*
   70 CONTINUE
      WORK( 1 ) = MAXWRK
      RETURN
*
*     End of DGELSS
*
      END
*> \brief <b> DGELSX solves overdetermined or underdetermined systems for GE matrices</b>
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGELSX + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgelsx.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgelsx.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgelsx.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGELSX( M, N, NRHS, A, LDA, B, LDB, JPVT, RCOND, RANK,
*                          WORK, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, LDA, LDB, M, N, NRHS, RANK
*       DOUBLE PRECISION   RCOND
*       ..
*       .. Array Arguments ..
*       INTEGER            JPVT( * )
*       DOUBLE PRECISION   A( LDA, * ), B( LDB, * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> This routine is deprecated and has been replaced by routine DGELSY.
*>
*> DGELSX computes the minimum-norm solution to a real linear least
*> squares problem:
*>     minimize || A * X - B ||
*> using a complete orthogonal factorization of A.  A is an M-by-N
*> matrix which may be rank-deficient.
*>
*> Several right hand side vectors b and solution vectors x can be
*> handled in a single call; they are stored as the columns of the
*> M-by-NRHS right hand side matrix B and the N-by-NRHS solution
*> matrix X.
*>
*> The routine first computes a QR factorization with column pivoting:
*>     A * P = Q * [ R11 R12 ]
*>                 [  0  R22 ]
*> with R11 defined as the largest leading submatrix whose estimated
*> condition number is less than 1/RCOND.  The order of R11, RANK,
*> is the effective rank of A.
*>
*> Then, R22 is considered to be negligible, and R12 is annihilated
*> by orthogonal transformations from the right, arriving at the
*> complete orthogonal factorization:
*>    A * P = Q * [ T11 0 ] * Z
*>                [  0  0 ]
*> The minimum-norm solution is then
*>    X = P * Z**T [ inv(T11)*Q1**T*B ]
*>                 [        0         ]
*> where Q1 consists of the first RANK columns of Q.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A.  M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in] NRHS
*> \verbatim
*>          NRHS is INTEGER
*>          The number of right hand sides, i.e., the number of
*>          columns of matrices B and X. NRHS >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the M-by-N matrix A.
*>          On exit, A has been overwritten by details of its
*>          complete orthogonal factorization.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,M).
*> \endverbatim
*>
*> \param[in,out] B
*> \verbatim
*>          B is DOUBLE PRECISION array, dimension (LDB,NRHS)
*>          On entry, the M-by-NRHS right hand side matrix B.
*>          On exit, the N-by-NRHS solution matrix X.
*>          If m >= n and RANK = n, the residual sum-of-squares for
*>          the solution in the i-th column is given by the sum of
*>          squares of elements N+1:M in that column.
*> \endverbatim
*>
*> \param[in] LDB
*> \verbatim
*>          LDB is INTEGER
*>          The leading dimension of the array B. LDB >= max(1,M,N).
*> \endverbatim
*>
*> \param[in,out] JPVT
*> \verbatim
*>          JPVT is INTEGER array, dimension (N)
*>          On entry, if JPVT(i) .ne. 0, the i-th column of A is an
*>          initial column, otherwise it is a free column.  Before
*>          the QR factorization of A, all initial columns are
*>          permuted to the leading positions; only the remaining
*>          free columns are moved as a result of column pivoting
*>          during the factorization.
*>          On exit, if JPVT(i) = k, then the i-th column of A*P
*>          was the k-th column of A.
*> \endverbatim
*>
*> \param[in] RCOND
*> \verbatim
*>          RCOND is DOUBLE PRECISION
*>          RCOND is used to determine the effective rank of A, which
*>          is defined as the order of the largest leading triangular
*>          submatrix R11 in the QR factorization with pivoting of A,
*>          whose estimated condition number < 1/RCOND.
*> \endverbatim
*>
*> \param[out] RANK
*> \verbatim
*>          RANK is INTEGER
*>          The effective rank of A, i.e., the order of the submatrix
*>          R11.  This is the same as the order of the submatrix T11
*>          in the complete orthogonal factorization of A.
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension
*>                      (max( min(M,N)+3*N, 2*min(M,N)+NRHS )),
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEsolve
*
*  =====================================================================
      SUBROUTINE DGELSX( M, N, NRHS, A, LDA, B, LDB, JPVT, RCOND, RANK,
     $                   WORK, INFO )
*
*  -- LAPACK driver routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER            INFO, LDA, LDB, M, N, NRHS, RANK
      DOUBLE PRECISION   RCOND
*     ..
*     .. Array Arguments ..
      INTEGER            JPVT( * )
      DOUBLE PRECISION   A( LDA, * ), B( LDB, * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      INTEGER            IMAX, IMIN
      PARAMETER          ( IMAX = 1, IMIN = 2 )
      DOUBLE PRECISION   ZERO, ONE, DONE, NTDONE
      PARAMETER          ( ZERO = 0.0D0, ONE = 1.0D0, DONE = ZERO,
     $                   NTDONE = ONE )
*     ..
*     .. Local Scalars ..
      INTEGER            I, IASCL, IBSCL, ISMAX, ISMIN, J, K, MN
      DOUBLE PRECISION   ANRM, BIGNUM, BNRM, C1, C2, S1, S2, SMAX,
     $                   SMAXPR, SMIN, SMINPR, SMLNUM, T1, T2
*     ..
*     .. External Functions ..
      DOUBLE PRECISION   DLAMCH, DLANGE
      EXTERNAL           DLAMCH, DLANGE
*     ..
*     .. External Subroutines ..
      EXTERNAL           DGEQPF, DLAIC1, DLASCL, DLASET, DLATZM, DORM2R,
     $                   DTRSM, DTZRQF, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          ABS, MAX, MIN
*     ..
*     .. Executable Statements ..
*
      MN = MIN( M, N )
      ISMIN = MN + 1
      ISMAX = 2*MN + 1
*
*     Test the input arguments.
*
      INFO = 0
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( NRHS.LT.0 ) THEN
         INFO = -3
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -5
      ELSE IF( LDB.LT.MAX( 1, M, N ) ) THEN
         INFO = -7
      END IF
*
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGELSX', -INFO )
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( MIN( M, N, NRHS ).EQ.0 ) THEN
         RANK = 0
         RETURN
      END IF
*
*     Get machine parameters
*
      SMLNUM = DLAMCH( 'S' ) / DLAMCH( 'P' )
      BIGNUM = ONE / SMLNUM
      CALL DLABAD( SMLNUM, BIGNUM )
*
*     Scale A, B if max elements outside range [SMLNUM,BIGNUM]
*
      ANRM = DLANGE( 'M', M, N, A, LDA, WORK )
      IASCL = 0
      IF( ANRM.GT.ZERO .AND. ANRM.LT.SMLNUM ) THEN
*
*        Scale matrix norm up to SMLNUM
*
         CALL DLASCL( 'G', 0, 0, ANRM, SMLNUM, M, N, A, LDA, INFO )
         IASCL = 1
      ELSE IF( ANRM.GT.BIGNUM ) THEN
*
*        Scale matrix norm down to BIGNUM
*
         CALL DLASCL( 'G', 0, 0, ANRM, BIGNUM, M, N, A, LDA, INFO )
         IASCL = 2
      ELSE IF( ANRM.EQ.ZERO ) THEN
*
*        Matrix all zero. Return zero solution.
*
         CALL DLASET( 'F', MAX( M, N ), NRHS, ZERO, ZERO, B, LDB )
         RANK = 0
         GO TO 100
      END IF
*
      BNRM = DLANGE( 'M', M, NRHS, B, LDB, WORK )
      IBSCL = 0
      IF( BNRM.GT.ZERO .AND. BNRM.LT.SMLNUM ) THEN
*
*        Scale matrix norm up to SMLNUM
*
         CALL DLASCL( 'G', 0, 0, BNRM, SMLNUM, M, NRHS, B, LDB, INFO )
         IBSCL = 1
      ELSE IF( BNRM.GT.BIGNUM ) THEN
*
*        Scale matrix norm down to BIGNUM
*
         CALL DLASCL( 'G', 0, 0, BNRM, BIGNUM, M, NRHS, B, LDB, INFO )
         IBSCL = 2
      END IF
*
*     Compute QR factorization with column pivoting of A:
*        A * P = Q * R
*
      CALL DGEQPF( M, N, A, LDA, JPVT, WORK( 1 ), WORK( MN+1 ), INFO )
*
*     workspace 3*N. Details of Householder rotations stored
*     in WORK(1:MN).
*
*     Determine RANK using incremental condition estimation
*
      WORK( ISMIN ) = ONE
      WORK( ISMAX ) = ONE
      SMAX = ABS( A( 1, 1 ) )
      SMIN = SMAX
      IF( ABS( A( 1, 1 ) ).EQ.ZERO ) THEN
         RANK = 0
         CALL DLASET( 'F', MAX( M, N ), NRHS, ZERO, ZERO, B, LDB )
         GO TO 100
      ELSE
         RANK = 1
      END IF
*
   10 CONTINUE
      IF( RANK.LT.MN ) THEN
         I = RANK + 1
         CALL DLAIC1( IMIN, RANK, WORK( ISMIN ), SMIN, A( 1, I ),
     $                A( I, I ), SMINPR, S1, C1 )
         CALL DLAIC1( IMAX, RANK, WORK( ISMAX ), SMAX, A( 1, I ),
     $                A( I, I ), SMAXPR, S2, C2 )
*
         IF( SMAXPR*RCOND.LE.SMINPR ) THEN
            DO 20 I = 1, RANK
               WORK( ISMIN+I-1 ) = S1*WORK( ISMIN+I-1 )
               WORK( ISMAX+I-1 ) = S2*WORK( ISMAX+I-1 )
   20       CONTINUE
            WORK( ISMIN+RANK ) = C1
            WORK( ISMAX+RANK ) = C2
            SMIN = SMINPR
            SMAX = SMAXPR
            RANK = RANK + 1
            GO TO 10
         END IF
      END IF
*
*     Logically partition R = [ R11 R12 ]
*                             [  0  R22 ]
*     where R11 = R(1:RANK,1:RANK)
*
*     [R11,R12] = [ T11, 0 ] * Y
*
      IF( RANK.LT.N )
     $   CALL DTZRQF( RANK, N, A, LDA, WORK( MN+1 ), INFO )
*
*     Details of Householder rotations stored in WORK(MN+1:2*MN)
*
*     B(1:M,1:NRHS) := Q**T * B(1:M,1:NRHS)
*
      CALL DORM2R( 'Left', 'Transpose', M, NRHS, MN, A, LDA, WORK( 1 ),
     $             B, LDB, WORK( 2*MN+1 ), INFO )
*
*     workspace NRHS
*
*     B(1:RANK,1:NRHS) := inv(T11) * B(1:RANK,1:NRHS)
*
      CALL DTRSM( 'Left', 'Upper', 'No transpose', 'Non-unit', RANK,
     $            NRHS, ONE, A, LDA, B, LDB )
*
      DO 40 I = RANK + 1, N
         DO 30 J = 1, NRHS
            B( I, J ) = ZERO
   30    CONTINUE
   40 CONTINUE
*
*     B(1:N,1:NRHS) := Y**T * B(1:N,1:NRHS)
*
      IF( RANK.LT.N ) THEN
         DO 50 I = 1, RANK
            CALL DLATZM( 'Left', N-RANK+1, NRHS, A( I, RANK+1 ), LDA,
     $                   WORK( MN+I ), B( I, 1 ), B( RANK+1, 1 ), LDB,
     $                   WORK( 2*MN+1 ) )
   50    CONTINUE
      END IF
*
*     workspace NRHS
*
*     B(1:N,1:NRHS) := P * B(1:N,1:NRHS)
*
      DO 90 J = 1, NRHS
         DO 60 I = 1, N
            WORK( 2*MN+I ) = NTDONE
   60    CONTINUE
         DO 80 I = 1, N
            IF( WORK( 2*MN+I ).EQ.NTDONE ) THEN
               IF( JPVT( I ).NE.I ) THEN
                  K = I
                  T1 = B( K, J )
                  T2 = B( JPVT( K ), J )
   70             CONTINUE
                  B( JPVT( K ), J ) = T1
                  WORK( 2*MN+K ) = DONE
                  T1 = T2
                  K = JPVT( K )
                  T2 = B( JPVT( K ), J )
                  IF( JPVT( K ).NE.I )
     $               GO TO 70
                  B( I, J ) = T1
                  WORK( 2*MN+K ) = DONE
               END IF
            END IF
   80    CONTINUE
   90 CONTINUE
*
*     Undo scaling
*
      IF( IASCL.EQ.1 ) THEN
         CALL DLASCL( 'G', 0, 0, ANRM, SMLNUM, N, NRHS, B, LDB, INFO )
         CALL DLASCL( 'U', 0, 0, SMLNUM, ANRM, RANK, RANK, A, LDA,
     $                INFO )
      ELSE IF( IASCL.EQ.2 ) THEN
         CALL DLASCL( 'G', 0, 0, ANRM, BIGNUM, N, NRHS, B, LDB, INFO )
         CALL DLASCL( 'U', 0, 0, BIGNUM, ANRM, RANK, RANK, A, LDA,
     $                INFO )
      END IF
      IF( IBSCL.EQ.1 ) THEN
         CALL DLASCL( 'G', 0, 0, SMLNUM, BNRM, N, NRHS, B, LDB, INFO )
      ELSE IF( IBSCL.EQ.2 ) THEN
         CALL DLASCL( 'G', 0, 0, BIGNUM, BNRM, N, NRHS, B, LDB, INFO )
      END IF
*
  100 CONTINUE
*
      RETURN
*
*     End of DGELSX
*
      END
*> \brief <b> DGELSY solves overdetermined or underdetermined systems for GE matrices</b>
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGELSY + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgelsy.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgelsy.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgelsy.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGELSY( M, N, NRHS, A, LDA, B, LDB, JPVT, RCOND, RANK,
*                          WORK, LWORK, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, LDA, LDB, LWORK, M, N, NRHS, RANK
*       DOUBLE PRECISION   RCOND
*       ..
*       .. Array Arguments ..
*       INTEGER            JPVT( * )
*       DOUBLE PRECISION   A( LDA, * ), B( LDB, * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGELSY computes the minimum-norm solution to a real linear least
*> squares problem:
*>     minimize || A * X - B ||
*> using a complete orthogonal factorization of A.  A is an M-by-N
*> matrix which may be rank-deficient.
*>
*> Several right hand side vectors b and solution vectors x can be
*> handled in a single call; they are stored as the columns of the
*> M-by-NRHS right hand side matrix B and the N-by-NRHS solution
*> matrix X.
*>
*> The routine first computes a QR factorization with column pivoting:
*>     A * P = Q * [ R11 R12 ]
*>                 [  0  R22 ]
*> with R11 defined as the largest leading submatrix whose estimated
*> condition number is less than 1/RCOND.  The order of R11, RANK,
*> is the effective rank of A.
*>
*> Then, R22 is considered to be negligible, and R12 is annihilated
*> by orthogonal transformations from the right, arriving at the
*> complete orthogonal factorization:
*>    A * P = Q * [ T11 0 ] * Z
*>                [  0  0 ]
*> The minimum-norm solution is then
*>    X = P * Z**T [ inv(T11)*Q1**T*B ]
*>                 [        0         ]
*> where Q1 consists of the first RANK columns of Q.
*>
*> This routine is basically identical to the original xGELSX except
*> three differences:
*>   o The call to the subroutine xGEQPF has been substituted by the
*>     the call to the subroutine xGEQP3. This subroutine is a Blas-3
*>     version of the QR factorization with column pivoting.
*>   o Matrix B (the right hand side) is updated with Blas-3.
*>   o The permutation of matrix B (the right hand side) is faster and
*>     more simple.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A.  M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in] NRHS
*> \verbatim
*>          NRHS is INTEGER
*>          The number of right hand sides, i.e., the number of
*>          columns of matrices B and X. NRHS >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the M-by-N matrix A.
*>          On exit, A has been overwritten by details of its
*>          complete orthogonal factorization.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,M).
*> \endverbatim
*>
*> \param[in,out] B
*> \verbatim
*>          B is DOUBLE PRECISION array, dimension (LDB,NRHS)
*>          On entry, the M-by-NRHS right hand side matrix B.
*>          On exit, the N-by-NRHS solution matrix X.
*> \endverbatim
*>
*> \param[in] LDB
*> \verbatim
*>          LDB is INTEGER
*>          The leading dimension of the array B. LDB >= max(1,M,N).
*> \endverbatim
*>
*> \param[in,out] JPVT
*> \verbatim
*>          JPVT is INTEGER array, dimension (N)
*>          On entry, if JPVT(i) .ne. 0, the i-th column of A is permuted
*>          to the front of AP, otherwise column i is a free column.
*>          On exit, if JPVT(i) = k, then the i-th column of AP
*>          was the k-th column of A.
*> \endverbatim
*>
*> \param[in] RCOND
*> \verbatim
*>          RCOND is DOUBLE PRECISION
*>          RCOND is used to determine the effective rank of A, which
*>          is defined as the order of the largest leading triangular
*>          submatrix R11 in the QR factorization with pivoting of A,
*>          whose estimated condition number < 1/RCOND.
*> \endverbatim
*>
*> \param[out] RANK
*> \verbatim
*>          RANK is INTEGER
*>          The effective rank of A, i.e., the order of the submatrix
*>          R11.  This is the same as the order of the submatrix T11
*>          in the complete orthogonal factorization of A.
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK))
*>          On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
*> \endverbatim
*>
*> \param[in] LWORK
*> \verbatim
*>          LWORK is INTEGER
*>          The dimension of the array WORK.
*>          The unblocked strategy requires that:
*>             LWORK >= MAX( MN+3*N+1, 2*MN+NRHS ),
*>          where MN = min( M, N ).
*>          The block algorithm requires that:
*>             LWORK >= MAX( MN+2*N+NB*(N+1), 2*MN+NB*NRHS ),
*>          where NB is an upper bound on the blocksize returned
*>          by ILAENV for the routines DGEQP3, DTZRZF, STZRQF, DORMQR,
*>          and DORMRZ.
*>
*>          If LWORK = -1, then a workspace query is assumed; the routine
*>          only calculates the optimal size of the WORK array, returns
*>          this value as the first entry of the WORK array, and no error
*>          message related to LWORK is issued by XERBLA.
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0: successful exit
*>          < 0: If INFO = -i, the i-th argument had an illegal value.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEsolve
*
*> \par Contributors:
*  ==================
*>
*>    A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA \n
*>    E. Quintana-Orti, Depto. de Informatica, Universidad Jaime I, Spain \n
*>    G. Quintana-Orti, Depto. de Informatica, Universidad Jaime I, Spain \n
*>
*  =====================================================================
      SUBROUTINE DGELSY( M, N, NRHS, A, LDA, B, LDB, JPVT, RCOND, RANK,
     $                   WORK, LWORK, INFO )
*
*  -- LAPACK driver routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER            INFO, LDA, LDB, LWORK, M, N, NRHS, RANK
      DOUBLE PRECISION   RCOND
*     ..
*     .. Array Arguments ..
      INTEGER            JPVT( * )
      DOUBLE PRECISION   A( LDA, * ), B( LDB, * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      INTEGER            IMAX, IMIN
      PARAMETER          ( IMAX = 1, IMIN = 2 )
      DOUBLE PRECISION   ZERO, ONE
      PARAMETER          ( ZERO = 0.0D+0, ONE = 1.0D+0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            LQUERY
      INTEGER            I, IASCL, IBSCL, ISMAX, ISMIN, J, LWKMIN,
     $                   LWKOPT, MN, NB, NB1, NB2, NB3, NB4
      DOUBLE PRECISION   ANRM, BIGNUM, BNRM, C1, C2, S1, S2, SMAX,
     $                   SMAXPR, SMIN, SMINPR, SMLNUM, WSIZE
*     ..
*     .. External Functions ..
      INTEGER            ILAENV
      DOUBLE PRECISION   DLAMCH, DLANGE
      EXTERNAL           ILAENV, DLAMCH, DLANGE
*     ..
*     .. External Subroutines ..
      EXTERNAL           DCOPY, DGEQP3, DLABAD, DLAIC1, DLASCL, DLASET,
     $                   DORMQR, DORMRZ, DTRSM, DTZRZF, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          ABS, MAX, MIN
*     ..
*     .. Executable Statements ..
*
      MN = MIN( M, N )
      ISMIN = MN + 1
      ISMAX = 2*MN + 1
*
*     Test the input arguments.
*
      INFO = 0
      LQUERY = ( LWORK.EQ.-1 )
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( NRHS.LT.0 ) THEN
         INFO = -3
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -5
      ELSE IF( LDB.LT.MAX( 1, M, N ) ) THEN
         INFO = -7
      END IF
*
*     Figure out optimal block size
*
      IF( INFO.EQ.0 ) THEN
         IF( MN.EQ.0 .OR. NRHS.EQ.0 ) THEN
            LWKMIN = 1
            LWKOPT = 1
         ELSE
            NB1 = ILAENV( 1, 'DGEQRF', ' ', M, N, -1, -1 )
            NB2 = ILAENV( 1, 'DGERQF', ' ', M, N, -1, -1 )
            NB3 = ILAENV( 1, 'DORMQR', ' ', M, N, NRHS, -1 )
            NB4 = ILAENV( 1, 'DORMRQ', ' ', M, N, NRHS, -1 )
            NB = MAX( NB1, NB2, NB3, NB4 )
            LWKMIN = MN + MAX( 2*MN, N + 1, MN + NRHS )
            LWKOPT = MAX( LWKMIN,
     $                    MN + 2*N + NB*( N + 1 ), 2*MN + NB*NRHS )
         END IF
         WORK( 1 ) = LWKOPT
*
         IF( LWORK.LT.LWKMIN .AND. .NOT.LQUERY ) THEN
            INFO = -12
         END IF
      END IF
*
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGELSY', -INFO )
         RETURN
      ELSE IF( LQUERY ) THEN
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( MN.EQ.0 .OR. NRHS.EQ.0 ) THEN
         RANK = 0
         RETURN
      END IF
*
*     Get machine parameters
*
      SMLNUM = DLAMCH( 'S' ) / DLAMCH( 'P' )
      BIGNUM = ONE / SMLNUM
      CALL DLABAD( SMLNUM, BIGNUM )
*
*     Scale A, B if max entries outside range [SMLNUM,BIGNUM]
*
      ANRM = DLANGE( 'M', M, N, A, LDA, WORK )
      IASCL = 0
      IF( ANRM.GT.ZERO .AND. ANRM.LT.SMLNUM ) THEN
*
*        Scale matrix norm up to SMLNUM
*
         CALL DLASCL( 'G', 0, 0, ANRM, SMLNUM, M, N, A, LDA, INFO )
         IASCL = 1
      ELSE IF( ANRM.GT.BIGNUM ) THEN
*
*        Scale matrix norm down to BIGNUM
*
         CALL DLASCL( 'G', 0, 0, ANRM, BIGNUM, M, N, A, LDA, INFO )
         IASCL = 2
      ELSE IF( ANRM.EQ.ZERO ) THEN
*
*        Matrix all zero. Return zero solution.
*
         CALL DLASET( 'F', MAX( M, N ), NRHS, ZERO, ZERO, B, LDB )
         RANK = 0
         GO TO 70
      END IF
*
      BNRM = DLANGE( 'M', M, NRHS, B, LDB, WORK )
      IBSCL = 0
      IF( BNRM.GT.ZERO .AND. BNRM.LT.SMLNUM ) THEN
*
*        Scale matrix norm up to SMLNUM
*
         CALL DLASCL( 'G', 0, 0, BNRM, SMLNUM, M, NRHS, B, LDB, INFO )
         IBSCL = 1
      ELSE IF( BNRM.GT.BIGNUM ) THEN
*
*        Scale matrix norm down to BIGNUM
*
         CALL DLASCL( 'G', 0, 0, BNRM, BIGNUM, M, NRHS, B, LDB, INFO )
         IBSCL = 2
      END IF
*
*     Compute QR factorization with column pivoting of A:
*        A * P = Q * R
*
      CALL DGEQP3( M, N, A, LDA, JPVT, WORK( 1 ), WORK( MN+1 ),
     $             LWORK-MN, INFO )
      WSIZE = MN + WORK( MN+1 )
*
*     workspace: MN+2*N+NB*(N+1).
*     Details of Householder rotations stored in WORK(1:MN).
*
*     Determine RANK using incremental condition estimation
*
      WORK( ISMIN ) = ONE
      WORK( ISMAX ) = ONE
      SMAX = ABS( A( 1, 1 ) )
      SMIN = SMAX
      IF( ABS( A( 1, 1 ) ).EQ.ZERO ) THEN
         RANK = 0
         CALL DLASET( 'F', MAX( M, N ), NRHS, ZERO, ZERO, B, LDB )
         GO TO 70
      ELSE
         RANK = 1
      END IF
*
   10 CONTINUE
      IF( RANK.LT.MN ) THEN
         I = RANK + 1
         CALL DLAIC1( IMIN, RANK, WORK( ISMIN ), SMIN, A( 1, I ),
     $                A( I, I ), SMINPR, S1, C1 )
         CALL DLAIC1( IMAX, RANK, WORK( ISMAX ), SMAX, A( 1, I ),
     $                A( I, I ), SMAXPR, S2, C2 )
*
         IF( SMAXPR*RCOND.LE.SMINPR ) THEN
            DO 20 I = 1, RANK
               WORK( ISMIN+I-1 ) = S1*WORK( ISMIN+I-1 )
               WORK( ISMAX+I-1 ) = S2*WORK( ISMAX+I-1 )
   20       CONTINUE
            WORK( ISMIN+RANK ) = C1
            WORK( ISMAX+RANK ) = C2
            SMIN = SMINPR
            SMAX = SMAXPR
            RANK = RANK + 1
            GO TO 10
         END IF
      END IF
*
*     workspace: 3*MN.
*
*     Logically partition R = [ R11 R12 ]
*                             [  0  R22 ]
*     where R11 = R(1:RANK,1:RANK)
*
*     [R11,R12] = [ T11, 0 ] * Y
*
      IF( RANK.LT.N )
     $   CALL DTZRZF( RANK, N, A, LDA, WORK( MN+1 ), WORK( 2*MN+1 ),
     $                LWORK-2*MN, INFO )
*
*     workspace: 2*MN.
*     Details of Householder rotations stored in WORK(MN+1:2*MN)
*
*     B(1:M,1:NRHS) := Q**T * B(1:M,1:NRHS)
*
      CALL DORMQR( 'Left', 'Transpose', M, NRHS, MN, A, LDA, WORK( 1 ),
     $             B, LDB, WORK( 2*MN+1 ), LWORK-2*MN, INFO )
      WSIZE = MAX( WSIZE, 2*MN+WORK( 2*MN+1 ) )
*
*     workspace: 2*MN+NB*NRHS.
*
*     B(1:RANK,1:NRHS) := inv(T11) * B(1:RANK,1:NRHS)
*
      CALL DTRSM( 'Left', 'Upper', 'No transpose', 'Non-unit', RANK,
     $            NRHS, ONE, A, LDA, B, LDB )
*
      DO 40 J = 1, NRHS
         DO 30 I = RANK + 1, N
            B( I, J ) = ZERO
   30    CONTINUE
   40 CONTINUE
*
*     B(1:N,1:NRHS) := Y**T * B(1:N,1:NRHS)
*
      IF( RANK.LT.N ) THEN
         CALL DORMRZ( 'Left', 'Transpose', N, NRHS, RANK, N-RANK, A,
     $                LDA, WORK( MN+1 ), B, LDB, WORK( 2*MN+1 ),
     $                LWORK-2*MN, INFO )
      END IF
*
*     workspace: 2*MN+NRHS.
*
*     B(1:N,1:NRHS) := P * B(1:N,1:NRHS)
*
      DO 60 J = 1, NRHS
         DO 50 I = 1, N
            WORK( JPVT( I ) ) = B( I, J )
   50    CONTINUE
         CALL DCOPY( N, WORK( 1 ), 1, B( 1, J ), 1 )
   60 CONTINUE
*
*     workspace: N.
*
*     Undo scaling
*
      IF( IASCL.EQ.1 ) THEN
         CALL DLASCL( 'G', 0, 0, ANRM, SMLNUM, N, NRHS, B, LDB, INFO )
         CALL DLASCL( 'U', 0, 0, SMLNUM, ANRM, RANK, RANK, A, LDA,
     $                INFO )
      ELSE IF( IASCL.EQ.2 ) THEN
         CALL DLASCL( 'G', 0, 0, ANRM, BIGNUM, N, NRHS, B, LDB, INFO )
         CALL DLASCL( 'U', 0, 0, BIGNUM, ANRM, RANK, RANK, A, LDA,
     $                INFO )
      END IF
      IF( IBSCL.EQ.1 ) THEN
         CALL DLASCL( 'G', 0, 0, SMLNUM, BNRM, N, NRHS, B, LDB, INFO )
      ELSE IF( IBSCL.EQ.2 ) THEN
         CALL DLASCL( 'G', 0, 0, BIGNUM, BNRM, N, NRHS, B, LDB, INFO )
      END IF
*
   70 CONTINUE
      WORK( 1 ) = LWKOPT
*
      RETURN
*
*     End of DGELSY
*
      END
*> \brief \b DGEMQRT
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGEMQRT + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgemqrt.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgemqrt.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgemqrt.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGEMQRT( SIDE, TRANS, M, N, K, NB, V, LDV, T, LDT,
*                          C, LDC, WORK, INFO )
*
*       .. Scalar Arguments ..
*       CHARACTER SIDE, TRANS
*       INTEGER   INFO, K, LDV, LDC, M, N, NB, LDT
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION V( LDV, * ), C( LDC, * ), T( LDT, * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGEMQRT overwrites the general real M-by-N matrix C with
*>
*>                 SIDE = 'L'     SIDE = 'R'
*> TRANS = 'N':      Q C            C Q
*> TRANS = 'T':   Q**T C            C Q**T
*>
*> where Q is a real orthogonal matrix defined as the product of K
*> elementary reflectors:
*>
*>       Q = H(1) H(2) . . . H(K) = I - V T V**T
*>
*> generated using the compact WY representation as returned by DGEQRT.
*>
*> Q is of order M if SIDE = 'L' and of order N  if SIDE = 'R'.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] SIDE
*> \verbatim
*>          SIDE is CHARACTER*1
*>          = 'L': apply Q or Q**T from the Left;
*>          = 'R': apply Q or Q**T from the Right.
*> \endverbatim
*>
*> \param[in] TRANS
*> \verbatim
*>          TRANS is CHARACTER*1
*>          = 'N':  No transpose, apply Q;
*>          = 'C':  Transpose, apply Q**T.
*> \endverbatim
*>
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix C. M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix C. N >= 0.
*> \endverbatim
*>
*> \param[in] K
*> \verbatim
*>          K is INTEGER
*>          The number of elementary reflectors whose product defines
*>          the matrix Q.
*>          If SIDE = 'L', M >= K >= 0;
*>          if SIDE = 'R', N >= K >= 0.
*> \endverbatim
*>
*> \param[in] NB
*> \verbatim
*>          NB is INTEGER
*>          The block size used for the storage of T.  K >= NB >= 1.
*>          This must be the same value of NB used to generate T
*>          in CGEQRT.
*> \endverbatim
*>
*> \param[in] V
*> \verbatim
*>          V is DOUBLE PRECISION array, dimension (LDV,K)
*>          The i-th column must contain the vector which defines the
*>          elementary reflector H(i), for i = 1,2,...,k, as returned by
*>          CGEQRT in the first K columns of its array argument A.
*> \endverbatim
*>
*> \param[in] LDV
*> \verbatim
*>          LDV is INTEGER
*>          The leading dimension of the array V.
*>          If SIDE = 'L', LDA >= max(1,M);
*>          if SIDE = 'R', LDA >= max(1,N).
*> \endverbatim
*>
*> \param[in] T
*> \verbatim
*>          T is DOUBLE PRECISION array, dimension (LDT,K)
*>          The upper triangular factors of the block reflectors
*>          as returned by CGEQRT, stored as a NB-by-N matrix.
*> \endverbatim
*>
*> \param[in] LDT
*> \verbatim
*>          LDT is INTEGER
*>          The leading dimension of the array T.  LDT >= NB.
*> \endverbatim
*>
*> \param[in,out] C
*> \verbatim
*>          C is DOUBLE PRECISION array, dimension (LDC,N)
*>          On entry, the M-by-N matrix C.
*>          On exit, C is overwritten by Q C, Q**T C, C Q**T or C Q.
*> \endverbatim
*>
*> \param[in] LDC
*> \verbatim
*>          LDC is INTEGER
*>          The leading dimension of the array C. LDC >= max(1,M).
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array. The dimension of
*>          WORK is N*NB if SIDE = 'L', or  M*NB if SIDE = 'R'.
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEcomputational
*
*  =====================================================================
      SUBROUTINE DGEMQRT( SIDE, TRANS, M, N, K, NB, V, LDV, T, LDT,
     $                   C, LDC, WORK, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      CHARACTER SIDE, TRANS
      INTEGER   INFO, K, LDV, LDC, M, N, NB, LDT
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION V( LDV, * ), C( LDC, * ), T( LDT, * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     ..
*     .. Local Scalars ..
      LOGICAL            LEFT, RIGHT, TRAN, NOTRAN
      INTEGER            I, IB, LDWORK, KF, Q
*     ..
*     .. External Functions ..
      LOGICAL            LSAME
      EXTERNAL           LSAME
*     ..
*     .. External Subroutines ..
      EXTERNAL           XERBLA, DLARFB
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, MIN
*     ..
*     .. Executable Statements ..
*
*     .. Test the input arguments ..
*
      INFO   = 0
      LEFT   = LSAME( SIDE,  'L' )
      RIGHT  = LSAME( SIDE,  'R' )
      TRAN   = LSAME( TRANS, 'T' )
      NOTRAN = LSAME( TRANS, 'N' )
*
      IF( LEFT ) THEN
         LDWORK = MAX( 1, N )
         Q = M
      ELSE IF ( RIGHT ) THEN
         LDWORK = MAX( 1, M )
         Q = N
      END IF
      IF( .NOT.LEFT .AND. .NOT.RIGHT ) THEN
         INFO = -1
      ELSE IF( .NOT.TRAN .AND. .NOT.NOTRAN ) THEN
         INFO = -2
      ELSE IF( M.LT.0 ) THEN
         INFO = -3
      ELSE IF( N.LT.0 ) THEN
         INFO = -4
      ELSE IF( K.LT.0 .OR. K.GT.Q ) THEN
         INFO = -5
      ELSE IF( NB.LT.1 .OR. (NB.GT.K .AND. K.GT.0)) THEN
         INFO = -6
      ELSE IF( LDV.LT.MAX( 1, Q ) ) THEN
         INFO = -8
      ELSE IF( LDT.LT.NB ) THEN
         INFO = -10
      ELSE IF( LDC.LT.MAX( 1, M ) ) THEN
         INFO = -12
      END IF
*
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGEMQRT', -INFO )
         RETURN
      END IF
*
*     .. Quick return if possible ..
*
      IF( M.EQ.0 .OR. N.EQ.0 .OR. K.EQ.0 ) RETURN
*
      IF( LEFT .AND. TRAN ) THEN
*
         DO I = 1, K, NB
            IB = MIN( NB, K-I+1 )
            CALL DLARFB( 'L', 'T', 'F', 'C', M-I+1, N, IB,
     $                   V( I, I ), LDV, T( 1, I ), LDT,
     $                   C( I, 1 ), LDC, WORK, LDWORK )
         END DO
*
      ELSE IF( RIGHT .AND. NOTRAN ) THEN
*
         DO I = 1, K, NB
            IB = MIN( NB, K-I+1 )
            CALL DLARFB( 'R', 'N', 'F', 'C', M, N-I+1, IB,
     $                   V( I, I ), LDV, T( 1, I ), LDT,
     $                   C( 1, I ), LDC, WORK, LDWORK )
         END DO
*
      ELSE IF( LEFT .AND. NOTRAN ) THEN
*
         KF = ((K-1)/NB)*NB+1
         DO I = KF, 1, -NB
            IB = MIN( NB, K-I+1 )
            CALL DLARFB( 'L', 'N', 'F', 'C', M-I+1, N, IB,
     $                   V( I, I ), LDV, T( 1, I ), LDT,
     $                   C( I, 1 ), LDC, WORK, LDWORK )
         END DO
*
      ELSE IF( RIGHT .AND. TRAN ) THEN
*
         KF = ((K-1)/NB)*NB+1
         DO I = KF, 1, -NB
            IB = MIN( NB, K-I+1 )
            CALL DLARFB( 'R', 'T', 'F', 'C', M, N-I+1, IB,
     $                   V( I, I ), LDV, T( 1, I ), LDT,
     $                   C( 1, I ), LDC, WORK, LDWORK )
         END DO
*
      END IF
*
      RETURN
*
*     End of DGEMQRT
*
      END
*> \brief \b DGEQL2 computes the QL factorization of a general rectangular matrix using an unblocked algorithm.
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGEQL2 + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgeql2.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgeql2.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgeql2.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGEQL2( M, N, A, LDA, TAU, WORK, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, LDA, M, N
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGEQL2 computes a QL factorization of a real m by n matrix A:
*> A = Q * L.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A.  M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the m by n matrix A.
*>          On exit, if m >= n, the lower triangle of the subarray
*>          A(m-n+1:m,1:n) contains the n by n lower triangular matrix L;
*>          if m <= n, the elements on and below the (n-m)-th
*>          superdiagonal contain the m by n lower trapezoidal matrix L;
*>          the remaining elements, with the array TAU, represent the
*>          orthogonal matrix Q as a product of elementary reflectors
*>          (see Further Details).
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,M).
*> \endverbatim
*>
*> \param[out] TAU
*> \verbatim
*>          TAU is DOUBLE PRECISION array, dimension (min(M,N))
*>          The scalar factors of the elementary reflectors (see Further
*>          Details).
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (N)
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0: successful exit
*>          < 0: if INFO = -i, the i-th argument had an illegal value
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEcomputational
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>  The matrix Q is represented as a product of elementary reflectors
*>
*>     Q = H(k) . . . H(2) H(1), where k = min(m,n).
*>
*>  Each H(i) has the form
*>
*>     H(i) = I - tau * v * v**T
*>
*>  where tau is a real scalar, and v is a real vector with
*>  v(m-k+i+1:m) = 0 and v(m-k+i) = 1; v(1:m-k+i-1) is stored on exit in
*>  A(1:m-k+i-1,n-k+i), and tau in TAU(i).
*> \endverbatim
*>
*  =====================================================================
      SUBROUTINE DGEQL2( M, N, A, LDA, TAU, WORK, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER            INFO, LDA, M, N
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ONE
      PARAMETER          ( ONE = 1.0D+0 )
*     ..
*     .. Local Scalars ..
      INTEGER            I, K
      DOUBLE PRECISION   AII
*     ..
*     .. External Subroutines ..
      EXTERNAL           DLARF, DLARFG, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, MIN
*     ..
*     .. Executable Statements ..
*
*     Test the input arguments
*
      INFO = 0
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -4
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGEQL2', -INFO )
         RETURN
      END IF
*
      K = MIN( M, N )
*
      DO 10 I = K, 1, -1
*
*        Generate elementary reflector H(i) to annihilate
*        A(1:m-k+i-1,n-k+i)
*
         CALL DLARFG( M-K+I, A( M-K+I, N-K+I ), A( 1, N-K+I ), 1,
     $                TAU( I ) )
*
*        Apply H(i) to A(1:m-k+i,1:n-k+i-1) from the left
*
         AII = A( M-K+I, N-K+I )
         A( M-K+I, N-K+I ) = ONE
         CALL DLARF( 'Left', M-K+I, N-K+I-1, A( 1, N-K+I ), 1, TAU( I ),
     $               A, LDA, WORK )
         A( M-K+I, N-K+I ) = AII
   10 CONTINUE
      RETURN
*
*     End of DGEQL2
*
      END
*> \brief \b DGEQLF
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGEQLF + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgeqlf.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgeqlf.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgeqlf.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGEQLF( M, N, A, LDA, TAU, WORK, LWORK, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, LDA, LWORK, M, N
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGEQLF computes a QL factorization of a real M-by-N matrix A:
*> A = Q * L.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A.  M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the M-by-N matrix A.
*>          On exit,
*>          if m >= n, the lower triangle of the subarray
*>          A(m-n+1:m,1:n) contains the N-by-N lower triangular matrix L;
*>          if m <= n, the elements on and below the (n-m)-th
*>          superdiagonal contain the M-by-N lower trapezoidal matrix L;
*>          the remaining elements, with the array TAU, represent the
*>          orthogonal matrix Q as a product of elementary reflectors
*>          (see Further Details).
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,M).
*> \endverbatim
*>
*> \param[out] TAU
*> \verbatim
*>          TAU is DOUBLE PRECISION array, dimension (min(M,N))
*>          The scalar factors of the elementary reflectors (see Further
*>          Details).
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK))
*>          On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
*> \endverbatim
*>
*> \param[in] LWORK
*> \verbatim
*>          LWORK is INTEGER
*>          The dimension of the array WORK.  LWORK >= max(1,N).
*>          For optimum performance LWORK >= N*NB, where NB is the
*>          optimal blocksize.
*>
*>          If LWORK = -1, then a workspace query is assumed; the routine
*>          only calculates the optimal size of the WORK array, returns
*>          this value as the first entry of the WORK array, and no error
*>          message related to LWORK is issued by XERBLA.
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEcomputational
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>  The matrix Q is represented as a product of elementary reflectors
*>
*>     Q = H(k) . . . H(2) H(1), where k = min(m,n).
*>
*>  Each H(i) has the form
*>
*>     H(i) = I - tau * v * v**T
*>
*>  where tau is a real scalar, and v is a real vector with
*>  v(m-k+i+1:m) = 0 and v(m-k+i) = 1; v(1:m-k+i-1) is stored on exit in
*>  A(1:m-k+i-1,n-k+i), and tau in TAU(i).
*> \endverbatim
*>
*  =====================================================================
      SUBROUTINE DGEQLF( M, N, A, LDA, TAU, WORK, LWORK, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER            INFO, LDA, LWORK, M, N
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Local Scalars ..
      LOGICAL            LQUERY
      INTEGER            I, IB, IINFO, IWS, K, KI, KK, LDWORK, LWKOPT,
     $                   MU, NB, NBMIN, NU, NX
*     ..
*     .. External Subroutines ..
      EXTERNAL           DGEQL2, DLARFB, DLARFT, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, MIN
*     ..
*     .. External Functions ..
      INTEGER            ILAENV
      EXTERNAL           ILAENV
*     ..
*     .. Executable Statements ..
*
*     Test the input arguments
*
      INFO = 0
      LQUERY = ( LWORK.EQ.-1 )
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -4
      END IF
*
      IF( INFO.EQ.0 ) THEN
         K = MIN( M, N )
         IF( K.EQ.0 ) THEN
            LWKOPT = 1
         ELSE
            NB = ILAENV( 1, 'DGEQLF', ' ', M, N, -1, -1 )
            LWKOPT = N*NB
         END IF
         WORK( 1 ) = LWKOPT
*
         IF( LWORK.LT.MAX( 1, N ) .AND. .NOT.LQUERY ) THEN
            INFO = -7
         END IF
      END IF
*
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGEQLF', -INFO )
         RETURN
      ELSE IF( LQUERY ) THEN
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( K.EQ.0 ) THEN
         RETURN
      END IF
*
      NBMIN = 2
      NX = 1
      IWS = N
      IF( NB.GT.1 .AND. NB.LT.K ) THEN
*
*        Determine when to cross over from blocked to unblocked code.
*
         NX = MAX( 0, ILAENV( 3, 'DGEQLF', ' ', M, N, -1, -1 ) )
         IF( NX.LT.K ) THEN
*
*           Determine if workspace is large enough for blocked code.
*
            LDWORK = N
            IWS = LDWORK*NB
            IF( LWORK.LT.IWS ) THEN
*
*              Not enough workspace to use optimal NB:  reduce NB and
*              determine the minimum value of NB.
*
               NB = LWORK / LDWORK
               NBMIN = MAX( 2, ILAENV( 2, 'DGEQLF', ' ', M, N, -1,
     $                 -1 ) )
            END IF
         END IF
      END IF
*
      IF( NB.GE.NBMIN .AND. NB.LT.K .AND. NX.LT.K ) THEN
*
*        Use blocked code initially.
*        The last kk columns are handled by the block method.
*
         KI = ( ( K-NX-1 ) / NB )*NB
         KK = MIN( K, KI+NB )
*
         DO 10 I = K - KK + KI + 1, K - KK + 1, -NB
            IB = MIN( K-I+1, NB )
*
*           Compute the QL factorization of the current block
*           A(1:m-k+i+ib-1,n-k+i:n-k+i+ib-1)
*
            CALL DGEQL2( M-K+I+IB-1, IB, A( 1, N-K+I ), LDA, TAU( I ),
     $                   WORK, IINFO )
            IF( N-K+I.GT.1 ) THEN
*
*              Form the triangular factor of the block reflector
*              H = H(i+ib-1) . . . H(i+1) H(i)
*
               CALL DLARFT( 'Backward', 'Columnwise', M-K+I+IB-1, IB,
     $                      A( 1, N-K+I ), LDA, TAU( I ), WORK, LDWORK )
*
*              Apply H**T to A(1:m-k+i+ib-1,1:n-k+i-1) from the left
*
               CALL DLARFB( 'Left', 'Transpose', 'Backward',
     $                      'Columnwise', M-K+I+IB-1, N-K+I-1, IB,
     $                      A( 1, N-K+I ), LDA, WORK, LDWORK, A, LDA,
     $                      WORK( IB+1 ), LDWORK )
            END IF
   10    CONTINUE
         MU = M - K + I + NB - 1
         NU = N - K + I + NB - 1
      ELSE
         MU = M
         NU = N
      END IF
*
*     Use unblocked code to factor the last or only block
*
      IF( MU.GT.0 .AND. NU.GT.0 )
     $   CALL DGEQL2( MU, NU, A, LDA, TAU, WORK, IINFO )
*
      WORK( 1 ) = IWS
      RETURN
*
*     End of DGEQLF
*
      END
*> \brief \b DGEQP3
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGEQP3 + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgeqp3.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgeqp3.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgeqp3.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGEQP3( M, N, A, LDA, JPVT, TAU, WORK, LWORK, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, LDA, LWORK, M, N
*       ..
*       .. Array Arguments ..
*       INTEGER            JPVT( * )
*       DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGEQP3 computes a QR factorization with column pivoting of a
*> matrix A:  A*P = Q*R  using Level 3 BLAS.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A. M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the M-by-N matrix A.
*>          On exit, the upper triangle of the array contains the
*>          min(M,N)-by-N upper trapezoidal matrix R; the elements below
*>          the diagonal, together with the array TAU, represent the
*>          orthogonal matrix Q as a product of min(M,N) elementary
*>          reflectors.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A. LDA >= max(1,M).
*> \endverbatim
*>
*> \param[in,out] JPVT
*> \verbatim
*>          JPVT is INTEGER array, dimension (N)
*>          On entry, if JPVT(J).ne.0, the J-th column of A is permuted
*>          to the front of A*P (a leading column); if JPVT(J)=0,
*>          the J-th column of A is a free column.
*>          On exit, if JPVT(J)=K, then the J-th column of A*P was the
*>          the K-th column of A.
*> \endverbatim
*>
*> \param[out] TAU
*> \verbatim
*>          TAU is DOUBLE PRECISION array, dimension (min(M,N))
*>          The scalar factors of the elementary reflectors.
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK))
*>          On exit, if INFO=0, WORK(1) returns the optimal LWORK.
*> \endverbatim
*>
*> \param[in] LWORK
*> \verbatim
*>          LWORK is INTEGER
*>          The dimension of the array WORK. LWORK >= 3*N+1.
*>          For optimal performance LWORK >= 2*N+( N+1 )*NB, where NB
*>          is the optimal blocksize.
*>
*>          If LWORK = -1, then a workspace query is assumed; the routine
*>          only calculates the optimal size of the WORK array, returns
*>          this value as the first entry of the WORK array, and no error
*>          message related to LWORK is issued by XERBLA.
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0: successful exit.
*>          < 0: if INFO = -i, the i-th argument had an illegal value.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEcomputational
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>  The matrix Q is represented as a product of elementary reflectors
*>
*>     Q = H(1) H(2) . . . H(k), where k = min(m,n).
*>
*>  Each H(i) has the form
*>
*>     H(i) = I - tau * v * v**T
*>
*>  where tau is a real scalar, and v is a real/complex vector
*>  with v(1:i-1) = 0 and v(i) = 1; v(i+1:m) is stored on exit in
*>  A(i+1:m,i), and tau in TAU(i).
*> \endverbatim
*
*> \par Contributors:
*  ==================
*>
*>    G. Quintana-Orti, Depto. de Informatica, Universidad Jaime I, Spain
*>    X. Sun, Computer Science Dept., Duke University, USA
*>
*  =====================================================================
      SUBROUTINE DGEQP3( M, N, A, LDA, JPVT, TAU, WORK, LWORK, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER            INFO, LDA, LWORK, M, N
*     ..
*     .. Array Arguments ..
      INTEGER            JPVT( * )
      DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      INTEGER            INB, INBMIN, IXOVER
      PARAMETER          ( INB = 1, INBMIN = 2, IXOVER = 3 )
*     ..
*     .. Local Scalars ..
      LOGICAL            LQUERY
      INTEGER            FJB, IWS, J, JB, LWKOPT, MINMN, MINWS, NA, NB,
     $                   NBMIN, NFXD, NX, SM, SMINMN, SN, TOPBMN
*     ..
*     .. External Subroutines ..
      EXTERNAL           DGEQRF, DLAQP2, DLAQPS, DORMQR, DSWAP, XERBLA
*     ..
*     .. External Functions ..
      INTEGER            ILAENV
      DOUBLE PRECISION   DNRM2
      EXTERNAL           ILAENV, DNRM2
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          INT, MAX, MIN
*     ..
*     .. Executable Statements ..
*
*     Test input arguments
*  ====================
*
      INFO = 0
      LQUERY = ( LWORK.EQ.-1 )
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -4
      END IF
*
      IF( INFO.EQ.0 ) THEN
         MINMN = MIN( M, N )
         IF( MINMN.EQ.0 ) THEN
            IWS = 1
            LWKOPT = 1
         ELSE
            IWS = 3*N + 1
            NB = ILAENV( INB, 'DGEQRF', ' ', M, N, -1, -1 )
            LWKOPT = 2*N + ( N + 1 )*NB
         END IF
         WORK( 1 ) = LWKOPT
*
         IF( ( LWORK.LT.IWS ) .AND. .NOT.LQUERY ) THEN
            INFO = -8
         END IF
      END IF
*
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGEQP3', -INFO )
         RETURN
      ELSE IF( LQUERY ) THEN
         RETURN
      END IF
*
*     Move initial columns up front.
*
      NFXD = 1
      DO 10 J = 1, N
         IF( JPVT( J ).NE.0 ) THEN
            IF( J.NE.NFXD ) THEN
               CALL DSWAP( M, A( 1, J ), 1, A( 1, NFXD ), 1 )
               JPVT( J ) = JPVT( NFXD )
               JPVT( NFXD ) = J
            ELSE
               JPVT( J ) = J
            END IF
            NFXD = NFXD + 1
         ELSE
            JPVT( J ) = J
         END IF
   10 CONTINUE
      NFXD = NFXD - 1
*
*     Factorize fixed columns
*  =======================
*
*     Compute the QR factorization of fixed columns and update
*     remaining columns.
*
      IF( NFXD.GT.0 ) THEN
         NA = MIN( M, NFXD )
*CC      CALL DGEQR2( M, NA, A, LDA, TAU, WORK, INFO )
         CALL DGEQRF( M, NA, A, LDA, TAU, WORK, LWORK, INFO )
         IWS = MAX( IWS, INT( WORK( 1 ) ) )
         IF( NA.LT.N ) THEN
*CC         CALL DORM2R( 'Left', 'Transpose', M, N-NA, NA, A, LDA,
*CC  $                   TAU, A( 1, NA+1 ), LDA, WORK, INFO )
            CALL DORMQR( 'Left', 'Transpose', M, N-NA, NA, A, LDA, TAU,
     $                   A( 1, NA+1 ), LDA, WORK, LWORK, INFO )
            IWS = MAX( IWS, INT( WORK( 1 ) ) )
         END IF
      END IF
*
*     Factorize free columns
*  ======================
*
      IF( NFXD.LT.MINMN ) THEN
*
         SM = M - NFXD
         SN = N - NFXD
         SMINMN = MINMN - NFXD
*
*        Determine the block size.
*
         NB = ILAENV( INB, 'DGEQRF', ' ', SM, SN, -1, -1 )
         NBMIN = 2
         NX = 0
*
         IF( ( NB.GT.1 ) .AND. ( NB.LT.SMINMN ) ) THEN
*
*           Determine when to cross over from blocked to unblocked code.
*
            NX = MAX( 0, ILAENV( IXOVER, 'DGEQRF', ' ', SM, SN, -1,
     $           -1 ) )
*
*
            IF( NX.LT.SMINMN ) THEN
*
*              Determine if workspace is large enough for blocked code.
*
               MINWS = 2*SN + ( SN+1 )*NB
               IWS = MAX( IWS, MINWS )
               IF( LWORK.LT.MINWS ) THEN
*
*                 Not enough workspace to use optimal NB: Reduce NB and
*                 determine the minimum value of NB.
*
                  NB = ( LWORK-2*SN ) / ( SN+1 )
                  NBMIN = MAX( 2, ILAENV( INBMIN, 'DGEQRF', ' ', SM, SN,
     $                    -1, -1 ) )
*
*
               END IF
            END IF
         END IF
*
*        Initialize partial column norms. The first N elements of work
*        store the exact column norms.
*
         DO 20 J = NFXD + 1, N
            WORK( J ) = DNRM2( SM, A( NFXD+1, J ), 1 )
            WORK( N+J ) = WORK( J )
   20    CONTINUE
*
         IF( ( NB.GE.NBMIN ) .AND. ( NB.LT.SMINMN ) .AND.
     $       ( NX.LT.SMINMN ) ) THEN
*
*           Use blocked code initially.
*
            J = NFXD + 1
*
*           Compute factorization: while loop.
*
*
            TOPBMN = MINMN - NX
   30       CONTINUE
            IF( J.LE.TOPBMN ) THEN
               JB = MIN( NB, TOPBMN-J+1 )
*
*              Factorize JB columns among columns J:N.
*
               CALL DLAQPS( M, N-J+1, J-1, JB, FJB, A( 1, J ), LDA,
     $                      JPVT( J ), TAU( J ), WORK( J ), WORK( N+J ),
     $                      WORK( 2*N+1 ), WORK( 2*N+JB+1 ), N-J+1 )
*
               J = J + FJB
               GO TO 30
            END IF
         ELSE
            J = NFXD + 1
         END IF
*
*        Use unblocked code to factor the last or only block.
*
*
         IF( J.LE.MINMN )
     $      CALL DLAQP2( M, N-J+1, J-1, A( 1, J ), LDA, JPVT( J ),
     $                   TAU( J ), WORK( J ), WORK( N+J ),
     $                   WORK( 2*N+1 ) )
*
      END IF
*
      WORK( 1 ) = IWS
      RETURN
*
*     End of DGEQP3
*
      END
*> \brief \b DGEQPF
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGEQPF + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgeqpf.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgeqpf.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgeqpf.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGEQPF( M, N, A, LDA, JPVT, TAU, WORK, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, LDA, M, N
*       ..
*       .. Array Arguments ..
*       INTEGER            JPVT( * )
*       DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> This routine is deprecated and has been replaced by routine DGEQP3.
*>
*> DGEQPF computes a QR factorization with column pivoting of a
*> real M-by-N matrix A: A*P = Q*R.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A. M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A. N >= 0
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the M-by-N matrix A.
*>          On exit, the upper triangle of the array contains the
*>          min(M,N)-by-N upper triangular matrix R; the elements
*>          below the diagonal, together with the array TAU,
*>          represent the orthogonal matrix Q as a product of
*>          min(m,n) elementary reflectors.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A. LDA >= max(1,M).
*> \endverbatim
*>
*> \param[in,out] JPVT
*> \verbatim
*>          JPVT is INTEGER array, dimension (N)
*>          On entry, if JPVT(i) .ne. 0, the i-th column of A is permuted
*>          to the front of A*P (a leading column); if JPVT(i) = 0,
*>          the i-th column of A is a free column.
*>          On exit, if JPVT(i) = k, then the i-th column of A*P
*>          was the k-th column of A.
*> \endverbatim
*>
*> \param[out] TAU
*> \verbatim
*>          TAU is DOUBLE PRECISION array, dimension (min(M,N))
*>          The scalar factors of the elementary reflectors.
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (3*N)
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEcomputational
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>  The matrix Q is represented as a product of elementary reflectors
*>
*>     Q = H(1) H(2) . . . H(n)
*>
*>  Each H(i) has the form
*>
*>     H = I - tau * v * v**T
*>
*>  where tau is a real scalar, and v is a real vector with
*>  v(1:i-1) = 0 and v(i) = 1; v(i+1:m) is stored on exit in A(i+1:m,i).
*>
*>  The matrix P is represented in jpvt as follows: If
*>     jpvt(j) = i
*>  then the jth column of P is the ith canonical unit vector.
*>
*>  Partial column norm updating strategy modified by
*>    Z. Drmac and Z. Bujanovic, Dept. of Mathematics,
*>    University of Zagreb, Croatia.
*>  -- April 2011                                                      --
*>  For more details see LAPACK Working Note 176.
*> \endverbatim
*>
*  =====================================================================
      SUBROUTINE DGEQPF( M, N, A, LDA, JPVT, TAU, WORK, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER            INFO, LDA, M, N
*     ..
*     .. Array Arguments ..
      INTEGER            JPVT( * )
      DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ZERO, ONE
      PARAMETER          ( ZERO = 0.0D+0, ONE = 1.0D+0 )
*     ..
*     .. Local Scalars ..
      INTEGER            I, ITEMP, J, MA, MN, PVT
      DOUBLE PRECISION   AII, TEMP, TEMP2, TOL3Z
*     ..
*     .. External Subroutines ..
      EXTERNAL           DGEQR2, DLARF, DLARFG, DORM2R, DSWAP, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          ABS, MAX, MIN, SQRT
*     ..
*     .. External Functions ..
      INTEGER            IDAMAX
      DOUBLE PRECISION   DLAMCH, DNRM2
      EXTERNAL           IDAMAX, DLAMCH, DNRM2
*     ..
*     .. Executable Statements ..
*
*     Test the input arguments
*
      INFO = 0
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -4
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGEQPF', -INFO )
         RETURN
      END IF
*
      MN = MIN( M, N )
      TOL3Z = SQRT(DLAMCH('Epsilon'))
*
*     Move initial columns up front
*
      ITEMP = 1
      DO 10 I = 1, N
         IF( JPVT( I ).NE.0 ) THEN
            IF( I.NE.ITEMP ) THEN
               CALL DSWAP( M, A( 1, I ), 1, A( 1, ITEMP ), 1 )
               JPVT( I ) = JPVT( ITEMP )
               JPVT( ITEMP ) = I
            ELSE
               JPVT( I ) = I
            END IF
            ITEMP = ITEMP + 1
         ELSE
            JPVT( I ) = I
         END IF
   10 CONTINUE
      ITEMP = ITEMP - 1
*
*     Compute the QR factorization and update remaining columns
*
      IF( ITEMP.GT.0 ) THEN
         MA = MIN( ITEMP, M )
         CALL DGEQR2( M, MA, A, LDA, TAU, WORK, INFO )
         IF( MA.LT.N ) THEN
            CALL DORM2R( 'Left', 'Transpose', M, N-MA, MA, A, LDA, TAU,
     $                   A( 1, MA+1 ), LDA, WORK, INFO )
         END IF
      END IF
*
      IF( ITEMP.LT.MN ) THEN
*
*        Initialize partial column norms. The first n elements of
*        work store the exact column norms.
*
         DO 20 I = ITEMP + 1, N
            WORK( I ) = DNRM2( M-ITEMP, A( ITEMP+1, I ), 1 )
            WORK( N+I ) = WORK( I )
   20    CONTINUE
*
*        Compute factorization
*
         DO 40 I = ITEMP + 1, MN
*
*           Determine ith pivot column and swap if necessary
*
            PVT = ( I-1 ) + IDAMAX( N-I+1, WORK( I ), 1 )
*
            IF( PVT.NE.I ) THEN
               CALL DSWAP( M, A( 1, PVT ), 1, A( 1, I ), 1 )
               ITEMP = JPVT( PVT )
               JPVT( PVT ) = JPVT( I )
               JPVT( I ) = ITEMP
               WORK( PVT ) = WORK( I )
               WORK( N+PVT ) = WORK( N+I )
            END IF
*
*           Generate elementary reflector H(i)
*
            IF( I.LT.M ) THEN
               CALL DLARFG( M-I+1, A( I, I ), A( I+1, I ), 1, TAU( I ) )
            ELSE
               CALL DLARFG( 1, A( M, M ), A( M, M ), 1, TAU( M ) )
            END IF
*
            IF( I.LT.N ) THEN
*
*              Apply H(i) to A(i:m,i+1:n) from the left
*
               AII = A( I, I )
               A( I, I ) = ONE
               CALL DLARF( 'LEFT', M-I+1, N-I, A( I, I ), 1, TAU( I ),
     $                     A( I, I+1 ), LDA, WORK( 2*N+1 ) )
               A( I, I ) = AII
            END IF
*
*           Update partial column norms
*
            DO 30 J = I + 1, N
               IF( WORK( J ).NE.ZERO ) THEN
*
*                 NOTE: The following 4 lines follow from the analysis in
*                 Lapack Working Note 176.
*
                  TEMP = ABS( A( I, J ) ) / WORK( J )
                  TEMP = MAX( ZERO, ( ONE+TEMP )*( ONE-TEMP ) )
                  TEMP2 = TEMP*( WORK( J ) / WORK( N+J ) )**2
                  IF( TEMP2 .LE. TOL3Z ) THEN
                     IF( M-I.GT.0 ) THEN
                        WORK( J ) = DNRM2( M-I, A( I+1, J ), 1 )
                        WORK( N+J ) = WORK( J )
                     ELSE
                        WORK( J ) = ZERO
                        WORK( N+J ) = ZERO
                     END IF
                  ELSE
                     WORK( J ) = WORK( J )*SQRT( TEMP )
                  END IF
               END IF
   30       CONTINUE
*
   40    CONTINUE
      END IF
      RETURN
*
*     End of DGEQPF
*
      END
*> \brief \b DGEQR2 computes the QR factorization of a general rectangular matrix using an unblocked algorithm.
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGEQR2 + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgeqr2.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgeqr2.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgeqr2.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGEQR2( M, N, A, LDA, TAU, WORK, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, LDA, M, N
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGEQR2 computes a QR factorization of a real m by n matrix A:
*> A = Q * R.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A.  M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the m by n matrix A.
*>          On exit, the elements on and above the diagonal of the array
*>          contain the min(m,n) by n upper trapezoidal matrix R (R is
*>          upper triangular if m >= n); the elements below the diagonal,
*>          with the array TAU, represent the orthogonal matrix Q as a
*>          product of elementary reflectors (see Further Details).
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,M).
*> \endverbatim
*>
*> \param[out] TAU
*> \verbatim
*>          TAU is DOUBLE PRECISION array, dimension (min(M,N))
*>          The scalar factors of the elementary reflectors (see Further
*>          Details).
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (N)
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0: successful exit
*>          < 0: if INFO = -i, the i-th argument had an illegal value
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEcomputational
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>  The matrix Q is represented as a product of elementary reflectors
*>
*>     Q = H(1) H(2) . . . H(k), where k = min(m,n).
*>
*>  Each H(i) has the form
*>
*>     H(i) = I - tau * v * v**T
*>
*>  where tau is a real scalar, and v is a real vector with
*>  v(1:i-1) = 0 and v(i) = 1; v(i+1:m) is stored on exit in A(i+1:m,i),
*>  and tau in TAU(i).
*> \endverbatim
*>
*  =====================================================================
      SUBROUTINE DGEQR2( M, N, A, LDA, TAU, WORK, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER            INFO, LDA, M, N
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ONE
      PARAMETER          ( ONE = 1.0D+0 )
*     ..
*     .. Local Scalars ..
      INTEGER            I, K
      DOUBLE PRECISION   AII
*     ..
*     .. External Subroutines ..
      EXTERNAL           DLARF, DLARFG, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, MIN
*     ..
*     .. Executable Statements ..
*
*     Test the input arguments
*
      INFO = 0
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -4
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGEQR2', -INFO )
         RETURN
      END IF
*
      K = MIN( M, N )
*
      DO 10 I = 1, K
*
*        Generate elementary reflector H(i) to annihilate A(i+1:m,i)
*
         CALL DLARFG( M-I+1, A( I, I ), A( MIN( I+1, M ), I ), 1,
     $                TAU( I ) )
         IF( I.LT.N ) THEN
*
*           Apply H(i) to A(i:m,i+1:n) from the left
*
            AII = A( I, I )
            A( I, I ) = ONE
            CALL DLARF( 'Left', M-I+1, N-I, A( I, I ), 1, TAU( I ),
     $                  A( I, I+1 ), LDA, WORK )
            A( I, I ) = AII
         END IF
   10 CONTINUE
      RETURN
*
*     End of DGEQR2
*
      END
*> \brief \b DGEQR2P computes the QR factorization of a general rectangular matrix with non-negative diagonal elements using an unblocked algorithm.
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGEQR2P + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgeqr2p.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgeqr2p.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgeqr2p.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGEQR2P( M, N, A, LDA, TAU, WORK, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, LDA, M, N
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGEQR2P computes a QR factorization of a real m by n matrix A:
*> A = Q * R. The diagonal entries of R are nonnegative.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A.  M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the m by n matrix A.
*>          On exit, the elements on and above the diagonal of the array
*>          contain the min(m,n) by n upper trapezoidal matrix R (R is
*>          upper triangular if m >= n). The diagonal entries of R are
*>          nonnegative; the elements below the diagonal,
*>          with the array TAU, represent the orthogonal matrix Q as a
*>          product of elementary reflectors (see Further Details).
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,M).
*> \endverbatim
*>
*> \param[out] TAU
*> \verbatim
*>          TAU is DOUBLE PRECISION array, dimension (min(M,N))
*>          The scalar factors of the elementary reflectors (see Further
*>          Details).
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (N)
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0: successful exit
*>          < 0: if INFO = -i, the i-th argument had an illegal value
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEcomputational
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>  The matrix Q is represented as a product of elementary reflectors
*>
*>     Q = H(1) H(2) . . . H(k), where k = min(m,n).
*>
*>  Each H(i) has the form
*>
*>     H(i) = I - tau * v * v**T
*>
*>  where tau is a real scalar, and v is a real vector with
*>  v(1:i-1) = 0 and v(i) = 1; v(i+1:m) is stored on exit in A(i+1:m,i),
*>  and tau in TAU(i).
*>
*> See Lapack Working Note 203 for details
*> \endverbatim
*>
*  =====================================================================
      SUBROUTINE DGEQR2P( M, N, A, LDA, TAU, WORK, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER            INFO, LDA, M, N
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ONE
      PARAMETER          ( ONE = 1.0D+0 )
*     ..
*     .. Local Scalars ..
      INTEGER            I, K
      DOUBLE PRECISION   AII
*     ..
*     .. External Subroutines ..
      EXTERNAL           DLARF, DLARFGP, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, MIN
*     ..
*     .. Executable Statements ..
*
*     Test the input arguments
*
      INFO = 0
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -4
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGEQR2P', -INFO )
         RETURN
      END IF
*
      K = MIN( M, N )
*
      DO 10 I = 1, K
*
*        Generate elementary reflector H(i) to annihilate A(i+1:m,i)
*
         CALL DLARFGP( M-I+1, A( I, I ), A( MIN( I+1, M ), I ), 1,
     $                TAU( I ) )
         IF( I.LT.N ) THEN
*
*           Apply H(i) to A(i:m,i+1:n) from the left
*
            AII = A( I, I )
            A( I, I ) = ONE
            CALL DLARF( 'Left', M-I+1, N-I, A( I, I ), 1, TAU( I ),
     $                  A( I, I+1 ), LDA, WORK )
            A( I, I ) = AII
         END IF
   10 CONTINUE
      RETURN
*
*     End of DGEQR2P
*
      END
*> \brief \b DGEQRF
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGEQRF + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgeqrf.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgeqrf.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgeqrf.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGEQRF( M, N, A, LDA, TAU, WORK, LWORK, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, LDA, LWORK, M, N
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGEQRF computes a QR factorization of a real M-by-N matrix A:
*> A = Q * R.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A.  M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the M-by-N matrix A.
*>          On exit, the elements on and above the diagonal of the array
*>          contain the min(M,N)-by-N upper trapezoidal matrix R (R is
*>          upper triangular if m >= n); the elements below the diagonal,
*>          with the array TAU, represent the orthogonal matrix Q as a
*>          product of min(m,n) elementary reflectors (see Further
*>          Details).
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,M).
*> \endverbatim
*>
*> \param[out] TAU
*> \verbatim
*>          TAU is DOUBLE PRECISION array, dimension (min(M,N))
*>          The scalar factors of the elementary reflectors (see Further
*>          Details).
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK))
*>          On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
*> \endverbatim
*>
*> \param[in] LWORK
*> \verbatim
*>          LWORK is INTEGER
*>          The dimension of the array WORK.  LWORK >= max(1,N).
*>          For optimum performance LWORK >= N*NB, where NB is
*>          the optimal blocksize.
*>
*>          If LWORK = -1, then a workspace query is assumed; the routine
*>          only calculates the optimal size of the WORK array, returns
*>          this value as the first entry of the WORK array, and no error
*>          message related to LWORK is issued by XERBLA.
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEcomputational
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>  The matrix Q is represented as a product of elementary reflectors
*>
*>     Q = H(1) H(2) . . . H(k), where k = min(m,n).
*>
*>  Each H(i) has the form
*>
*>     H(i) = I - tau * v * v**T
*>
*>  where tau is a real scalar, and v is a real vector with
*>  v(1:i-1) = 0 and v(i) = 1; v(i+1:m) is stored on exit in A(i+1:m,i),
*>  and tau in TAU(i).
*> \endverbatim
*>
*  =====================================================================
      SUBROUTINE DGEQRF( M, N, A, LDA, TAU, WORK, LWORK, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER            INFO, LDA, LWORK, M, N
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Local Scalars ..
      LOGICAL            LQUERY
      INTEGER            I, IB, IINFO, IWS, K, LDWORK, LWKOPT, NB,
     $                   NBMIN, NX
*     ..
*     .. External Subroutines ..
      EXTERNAL           DGEQR2, DLARFB, DLARFT, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, MIN
*     ..
*     .. External Functions ..
      INTEGER            ILAENV
      EXTERNAL           ILAENV
*     ..
*     .. Executable Statements ..
*
*     Test the input arguments
*
      INFO = 0
      NB = ILAENV( 1, 'DGEQRF', ' ', M, N, -1, -1 )
      LWKOPT = N*NB
      WORK( 1 ) = LWKOPT
      LQUERY = ( LWORK.EQ.-1 )
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -4
      ELSE IF( LWORK.LT.MAX( 1, N ) .AND. .NOT.LQUERY ) THEN
         INFO = -7
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGEQRF', -INFO )
         RETURN
      ELSE IF( LQUERY ) THEN
         RETURN
      END IF
*
*     Quick return if possible
*
      K = MIN( M, N )
      IF( K.EQ.0 ) THEN
         WORK( 1 ) = 1
         RETURN
      END IF
*
      NBMIN = 2
      NX = 0
      IWS = N
      IF( NB.GT.1 .AND. NB.LT.K ) THEN
*
*        Determine when to cross over from blocked to unblocked code.
*
         NX = MAX( 0, ILAENV( 3, 'DGEQRF', ' ', M, N, -1, -1 ) )
         IF( NX.LT.K ) THEN
*
*           Determine if workspace is large enough for blocked code.
*
            LDWORK = N
            IWS = LDWORK*NB
            IF( LWORK.LT.IWS ) THEN
*
*              Not enough workspace to use optimal NB:  reduce NB and
*              determine the minimum value of NB.
*
               NB = LWORK / LDWORK
               NBMIN = MAX( 2, ILAENV( 2, 'DGEQRF', ' ', M, N, -1,
     $                 -1 ) )
            END IF
         END IF
      END IF
*
      IF( NB.GE.NBMIN .AND. NB.LT.K .AND. NX.LT.K ) THEN
*
*        Use blocked code initially
*
         DO 10 I = 1, K - NX, NB
            IB = MIN( K-I+1, NB )
*
*           Compute the QR factorization of the current block
*           A(i:m,i:i+ib-1)
*
            CALL DGEQR2( M-I+1, IB, A( I, I ), LDA, TAU( I ), WORK,
     $                   IINFO )
            IF( I+IB.LE.N ) THEN
*
*              Form the triangular factor of the block reflector
*              H = H(i) H(i+1) . . . H(i+ib-1)
*
               CALL DLARFT( 'Forward', 'Columnwise', M-I+1, IB,
     $                      A( I, I ), LDA, TAU( I ), WORK, LDWORK )
*
*              Apply H**T to A(i:m,i+ib:n) from the left
*
               CALL DLARFB( 'Left', 'Transpose', 'Forward',
     $                      'Columnwise', M-I+1, N-I-IB+1, IB,
     $                      A( I, I ), LDA, WORK, LDWORK, A( I, I+IB ),
     $                      LDA, WORK( IB+1 ), LDWORK )
            END IF
   10    CONTINUE
      ELSE
         I = 1
      END IF
*
*     Use unblocked code to factor the last or only block.
*
      IF( I.LE.K )
     $   CALL DGEQR2( M-I+1, N-I+1, A( I, I ), LDA, TAU( I ), WORK,
     $                IINFO )
*
      WORK( 1 ) = IWS
      RETURN
*
*     End of DGEQRF
*
      END
*> \brief \b DGEQRFP
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGEQRFP + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgeqrfp.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgeqrfp.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgeqrfp.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGEQRFP( M, N, A, LDA, TAU, WORK, LWORK, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, LDA, LWORK, M, N
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGEQRFP computes a QR factorization of a real M-by-N matrix A:
*> A = Q * R. The diagonal entries of R are nonnegative.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A.  M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the M-by-N matrix A.
*>          On exit, the elements on and above the diagonal of the array
*>          contain the min(M,N)-by-N upper trapezoidal matrix R (R is
*>          upper triangular if m >= n). The diagonal entries of R
*>          are nonnegative; the elements below the diagonal,
*>          with the array TAU, represent the orthogonal matrix Q as a
*>          product of min(m,n) elementary reflectors (see Further
*>          Details).
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,M).
*> \endverbatim
*>
*> \param[out] TAU
*> \verbatim
*>          TAU is DOUBLE PRECISION array, dimension (min(M,N))
*>          The scalar factors of the elementary reflectors (see Further
*>          Details).
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK))
*>          On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
*> \endverbatim
*>
*> \param[in] LWORK
*> \verbatim
*>          LWORK is INTEGER
*>          The dimension of the array WORK.  LWORK >= max(1,N).
*>          For optimum performance LWORK >= N*NB, where NB is
*>          the optimal blocksize.
*>
*>          If LWORK = -1, then a workspace query is assumed; the routine
*>          only calculates the optimal size of the WORK array, returns
*>          this value as the first entry of the WORK array, and no error
*>          message related to LWORK is issued by XERBLA.
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEcomputational
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>  The matrix Q is represented as a product of elementary reflectors
*>
*>     Q = H(1) H(2) . . . H(k), where k = min(m,n).
*>
*>  Each H(i) has the form
*>
*>     H(i) = I - tau * v * v**T
*>
*>  where tau is a real scalar, and v is a real vector with
*>  v(1:i-1) = 0 and v(i) = 1; v(i+1:m) is stored on exit in A(i+1:m,i),
*>  and tau in TAU(i).
*>
*> See Lapack Working Note 203 for details
*> \endverbatim
*>
*  =====================================================================
      SUBROUTINE DGEQRFP( M, N, A, LDA, TAU, WORK, LWORK, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER            INFO, LDA, LWORK, M, N
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Local Scalars ..
      LOGICAL            LQUERY
      INTEGER            I, IB, IINFO, IWS, K, LDWORK, LWKOPT, NB,
     $                   NBMIN, NX
*     ..
*     .. External Subroutines ..
      EXTERNAL           DGEQR2P, DLARFB, DLARFT, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, MIN
*     ..
*     .. External Functions ..
      INTEGER            ILAENV
      EXTERNAL           ILAENV
*     ..
*     .. Executable Statements ..
*
*     Test the input arguments
*
      INFO = 0
      NB = ILAENV( 1, 'DGEQRF', ' ', M, N, -1, -1 )
      LWKOPT = N*NB
      WORK( 1 ) = LWKOPT
      LQUERY = ( LWORK.EQ.-1 )
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -4
      ELSE IF( LWORK.LT.MAX( 1, N ) .AND. .NOT.LQUERY ) THEN
         INFO = -7
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGEQRFP', -INFO )
         RETURN
      ELSE IF( LQUERY ) THEN
         RETURN
      END IF
*
*     Quick return if possible
*
      K = MIN( M, N )
      IF( K.EQ.0 ) THEN
         WORK( 1 ) = 1
         RETURN
      END IF
*
      NBMIN = 2
      NX = 0
      IWS = N
      IF( NB.GT.1 .AND. NB.LT.K ) THEN
*
*        Determine when to cross over from blocked to unblocked code.
*
         NX = MAX( 0, ILAENV( 3, 'DGEQRF', ' ', M, N, -1, -1 ) )
         IF( NX.LT.K ) THEN
*
*           Determine if workspace is large enough for blocked code.
*
            LDWORK = N
            IWS = LDWORK*NB
            IF( LWORK.LT.IWS ) THEN
*
*              Not enough workspace to use optimal NB:  reduce NB and
*              determine the minimum value of NB.
*
               NB = LWORK / LDWORK
               NBMIN = MAX( 2, ILAENV( 2, 'DGEQRF', ' ', M, N, -1,
     $                 -1 ) )
            END IF
         END IF
      END IF
*
      IF( NB.GE.NBMIN .AND. NB.LT.K .AND. NX.LT.K ) THEN
*
*        Use blocked code initially
*
         DO 10 I = 1, K - NX, NB
            IB = MIN( K-I+1, NB )
*
*           Compute the QR factorization of the current block
*           A(i:m,i:i+ib-1)
*
            CALL DGEQR2P( M-I+1, IB, A( I, I ), LDA, TAU( I ), WORK,
     $                   IINFO )
            IF( I+IB.LE.N ) THEN
*
*              Form the triangular factor of the block reflector
*              H = H(i) H(i+1) . . . H(i+ib-1)
*
               CALL DLARFT( 'Forward', 'Columnwise', M-I+1, IB,
     $                      A( I, I ), LDA, TAU( I ), WORK, LDWORK )
*
*              Apply H**T to A(i:m,i+ib:n) from the left
*
               CALL DLARFB( 'Left', 'Transpose', 'Forward',
     $                      'Columnwise', M-I+1, N-I-IB+1, IB,
     $                      A( I, I ), LDA, WORK, LDWORK, A( I, I+IB ),
     $                      LDA, WORK( IB+1 ), LDWORK )
            END IF
   10    CONTINUE
      ELSE
         I = 1
      END IF
*
*     Use unblocked code to factor the last or only block.
*
      IF( I.LE.K )
     $   CALL DGEQR2P( M-I+1, N-I+1, A( I, I ), LDA, TAU( I ), WORK,
     $                IINFO )
*
      WORK( 1 ) = IWS
      RETURN
*
*     End of DGEQRFP
*
      END
*> \brief \b DGEQRT
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGEQRT + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgeqrt.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgeqrt.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgeqrt.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGEQRT( M, N, NB, A, LDA, T, LDT, WORK, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER INFO, LDA, LDT, M, N, NB
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION A( LDA, * ), T( LDT, * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGEQRT computes a blocked QR factorization of a real M-by-N matrix A
*> using the compact WY representation of Q.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A.  M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in] NB
*> \verbatim
*>          NB is INTEGER
*>          The block size to be used in the blocked QR.  MIN(M,N) >= NB >= 1.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the M-by-N matrix A.
*>          On exit, the elements on and above the diagonal of the array
*>          contain the min(M,N)-by-N upper trapezoidal matrix R (R is
*>          upper triangular if M >= N); the elements below the diagonal
*>          are the columns of V.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,M).
*> \endverbatim
*>
*> \param[out] T
*> \verbatim
*>          T is DOUBLE PRECISION array, dimension (LDT,MIN(M,N))
*>          The upper triangular block reflectors stored in compact form
*>          as a sequence of upper triangular blocks.  See below
*>          for further details.
*> \endverbatim
*>
*> \param[in] LDT
*> \verbatim
*>          LDT is INTEGER
*>          The leading dimension of the array T.  LDT >= NB.
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (NB*N)
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date June 2017
*
*> \ingroup doubleGEcomputational
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>  The matrix V stores the elementary reflectors H(i) in the i-th column
*>  below the diagonal. For example, if M=5 and N=3, the matrix V is
*>
*>               V = (  1       )
*>                   ( v1  1    )
*>                   ( v1 v2  1 )
*>                   ( v1 v2 v3 )
*>                   ( v1 v2 v3 )
*>
*>  where the vi's represent the vectors which define H(i), which are returned
*>  in the matrix A.  The 1's along the diagonal of V are not stored in A.
*>
*>  Let K=MIN(M,N).  The number of blocks is B = ceiling(K/NB), where each
*>  block is of order NB except for the last block, which is of order
*>  IB = K - (B-1)*NB.  For each of the B blocks, a upper triangular block
*>  reflector factor is computed: T1, T2, ..., TB.  The NB-by-NB (and IB-by-IB
*>  for the last block) T's are stored in the NB-by-K matrix T as
*>
*>               T = (T1 T2 ... TB).
*> \endverbatim
*>
*  =====================================================================
      SUBROUTINE DGEQRT( M, N, NB, A, LDA, T, LDT, WORK, INFO )
*
*  -- LAPACK computational routine (version 3.7.1) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     June 2017
*
*     .. Scalar Arguments ..
      INTEGER INFO, LDA, LDT, M, N, NB
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION A( LDA, * ), T( LDT, * ), WORK( * )
*     ..
*
* =====================================================================
*
*     ..
*     .. Local Scalars ..
      INTEGER    I, IB, IINFO, K
      LOGICAL    USE_RECURSIVE_QR
      PARAMETER( USE_RECURSIVE_QR=.TRUE. )
*     ..
*     .. External Subroutines ..
      EXTERNAL   DGEQRT2, DGEQRT3, DLARFB, XERBLA
*     ..
*     .. Executable Statements ..
*
*     Test the input arguments
*
      INFO = 0
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( NB.LT.1 .OR. ( NB.GT.MIN(M,N) .AND. MIN(M,N).GT.0 ) )THEN
         INFO = -3
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -5
      ELSE IF( LDT.LT.NB ) THEN
         INFO = -7
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGEQRT', -INFO )
         RETURN
      END IF
*
*     Quick return if possible
*
      K = MIN( M, N )
      IF( K.EQ.0 ) RETURN
*
*     Blocked loop of length K
*
      DO I = 1, K,  NB
         IB = MIN( K-I+1, NB )
*
*     Compute the QR factorization of the current block A(I:M,I:I+IB-1)
*
         IF( USE_RECURSIVE_QR ) THEN
            CALL DGEQRT3( M-I+1, IB, A(I,I), LDA, T(1,I), LDT, IINFO )
         ELSE
            CALL DGEQRT2( M-I+1, IB, A(I,I), LDA, T(1,I), LDT, IINFO )
         END IF
         IF( I+IB.LE.N ) THEN
*
*     Update by applying H**T to A(I:M,I+IB:N) from the left
*
            CALL DLARFB( 'L', 'T', 'F', 'C', M-I+1, N-I-IB+1, IB,
     $                   A( I, I ), LDA, T( 1, I ), LDT,
     $                   A( I, I+IB ), LDA, WORK , N-I-IB+1 )
         END IF
      END DO
      RETURN
*
*     End of DGEQRT
*
      END
*> \brief \b DGEQRT2 computes a QR factorization of a general real or complex matrix using the compact WY representation of Q.
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGEQRT2 + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgeqrt2.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgeqrt2.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgeqrt2.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGEQRT2( M, N, A, LDA, T, LDT, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER   INFO, LDA, LDT, M, N
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   A( LDA, * ), T( LDT, * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGEQRT2 computes a QR factorization of a real M-by-N matrix A,
*> using the compact WY representation of Q.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A.  M >= N.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the real M-by-N matrix A.  On exit, the elements on and
*>          above the diagonal contain the N-by-N upper triangular matrix R; the
*>          elements below the diagonal are the columns of V.  See below for
*>          further details.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,M).
*> \endverbatim
*>
*> \param[out] T
*> \verbatim
*>          T is DOUBLE PRECISION array, dimension (LDT,N)
*>          The N-by-N upper triangular factor of the block reflector.
*>          The elements on and above the diagonal contain the block
*>          reflector T; the elements below the diagonal are not used.
*>          See below for further details.
*> \endverbatim
*>
*> \param[in] LDT
*> \verbatim
*>          LDT is INTEGER
*>          The leading dimension of the array T.  LDT >= max(1,N).
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0: successful exit
*>          < 0: if INFO = -i, the i-th argument had an illegal value
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEcomputational
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>  The matrix V stores the elementary reflectors H(i) in the i-th column
*>  below the diagonal. For example, if M=5 and N=3, the matrix V is
*>
*>               V = (  1       )
*>                   ( v1  1    )
*>                   ( v1 v2  1 )
*>                   ( v1 v2 v3 )
*>                   ( v1 v2 v3 )
*>
*>  where the vi's represent the vectors which define H(i), which are returned
*>  in the matrix A.  The 1's along the diagonal of V are not stored in A.  The
*>  block reflector H is then given by
*>
*>               H = I - V * T * V**T
*>
*>  where V**T is the transpose of V.
*> \endverbatim
*>
*  =====================================================================
      SUBROUTINE DGEQRT2( M, N, A, LDA, T, LDT, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER   INFO, LDA, LDT, M, N
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   A( LDA, * ), T( LDT, * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION  ONE, ZERO
      PARAMETER( ONE = 1.0D+00, ZERO = 0.0D+00 )
*     ..
*     .. Local Scalars ..
      INTEGER   I, K
      DOUBLE PRECISION   AII, ALPHA
*     ..
*     .. External Subroutines ..
      EXTERNAL  DLARFG, DGEMV, DGER, DTRMV, XERBLA
*     ..
*     .. Executable Statements ..
*
*     Test the input arguments
*
      INFO = 0
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -4
      ELSE IF( LDT.LT.MAX( 1, N ) ) THEN
         INFO = -6
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGEQRT2', -INFO )
         RETURN
      END IF
*
      K = MIN( M, N )
*
      DO I = 1, K
*
*        Generate elem. refl. H(i) to annihilate A(i+1:m,i), tau(I) -> T(I,1)
*
         CALL DLARFG( M-I+1, A( I, I ), A( MIN( I+1, M ), I ), 1,
     $                T( I, 1 ) )
         IF( I.LT.N ) THEN
*
*           Apply H(i) to A(I:M,I+1:N) from the left
*
            AII = A( I, I )
            A( I, I ) = ONE
*
*           W(1:N-I) := A(I:M,I+1:N)^H * A(I:M,I) [W = T(:,N)]
*
            CALL DGEMV( 'T',M-I+1, N-I, ONE, A( I, I+1 ), LDA,
     $                  A( I, I ), 1, ZERO, T( 1, N ), 1 )
*
*           A(I:M,I+1:N) = A(I:m,I+1:N) + alpha*A(I:M,I)*W(1:N-1)^H
*
            ALPHA = -(T( I, 1 ))
            CALL DGER( M-I+1, N-I, ALPHA, A( I, I ), 1,
     $           T( 1, N ), 1, A( I, I+1 ), LDA )
            A( I, I ) = AII
         END IF
      END DO
*
      DO I = 2, N
         AII = A( I, I )
         A( I, I ) = ONE
*
*        T(1:I-1,I) := alpha * A(I:M,1:I-1)**T * A(I:M,I)
*
         ALPHA = -T( I, 1 )
         CALL DGEMV( 'T', M-I+1, I-1, ALPHA, A( I, 1 ), LDA,
     $               A( I, I ), 1, ZERO, T( 1, I ), 1 )
         A( I, I ) = AII
*
*        T(1:I-1,I) := T(1:I-1,1:I-1) * T(1:I-1,I)
*
         CALL DTRMV( 'U', 'N', 'N', I-1, T, LDT, T( 1, I ), 1 )
*
*           T(I,I) = tau(I)
*
            T( I, I ) = T( I, 1 )
            T( I, 1) = ZERO
      END DO

*
*     End of DGEQRT2
*
      END
*> \brief \b DGEQRT3 recursively computes a QR factorization of a general real or complex matrix using the compact WY representation of Q.
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGEQRT3 + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgeqrt3.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgeqrt3.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgeqrt3.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       RECURSIVE SUBROUTINE DGEQRT3( M, N, A, LDA, T, LDT, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER   INFO, LDA, M, N, LDT
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   A( LDA, * ), T( LDT, * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGEQRT3 recursively computes a QR factorization of a real M-by-N
*> matrix A, using the compact WY representation of Q.
*>
*> Based on the algorithm of Elmroth and Gustavson,
*> IBM J. Res. Develop. Vol 44 No. 4 July 2000.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A.  M >= N.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the real M-by-N matrix A.  On exit, the elements on and
*>          above the diagonal contain the N-by-N upper triangular matrix R; the
*>          elements below the diagonal are the columns of V.  See below for
*>          further details.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,M).
*> \endverbatim
*>
*> \param[out] T
*> \verbatim
*>          T is DOUBLE PRECISION array, dimension (LDT,N)
*>          The N-by-N upper triangular factor of the block reflector.
*>          The elements on and above the diagonal contain the block
*>          reflector T; the elements below the diagonal are not used.
*>          See below for further details.
*> \endverbatim
*>
*> \param[in] LDT
*> \verbatim
*>          LDT is INTEGER
*>          The leading dimension of the array T.  LDT >= max(1,N).
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0: successful exit
*>          < 0: if INFO = -i, the i-th argument had an illegal value
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date June 2016
*
*> \ingroup doubleGEcomputational
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>  The matrix V stores the elementary reflectors H(i) in the i-th column
*>  below the diagonal. For example, if M=5 and N=3, the matrix V is
*>
*>               V = (  1       )
*>                   ( v1  1    )
*>                   ( v1 v2  1 )
*>                   ( v1 v2 v3 )
*>                   ( v1 v2 v3 )
*>
*>  where the vi's represent the vectors which define H(i), which are returned
*>  in the matrix A.  The 1's along the diagonal of V are not stored in A.  The
*>  block reflector H is then given by
*>
*>               H = I - V * T * V**T
*>
*>  where V**T is the transpose of V.
*>
*>  For details of the algorithm, see Elmroth and Gustavson (cited above).
*> \endverbatim
*>
*  =====================================================================
      RECURSIVE SUBROUTINE DGEQRT3( M, N, A, LDA, T, LDT, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     June 2016
*
*     .. Scalar Arguments ..
      INTEGER   INFO, LDA, M, N, LDT
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   A( LDA, * ), T( LDT, * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ONE
      PARAMETER ( ONE = 1.0D+00 )
*     ..
*     .. Local Scalars ..
      INTEGER   I, I1, J, J1, N1, N2, IINFO
*     ..
*     .. External Subroutines ..
      EXTERNAL  DLARFG, DTRMM, DGEMM, XERBLA
*     ..
*     .. Executable Statements ..
*
      INFO = 0
      IF( N .LT. 0 ) THEN
         INFO = -2
      ELSE IF( M .LT. N ) THEN
         INFO = -1
      ELSE IF( LDA .LT. MAX( 1, M ) ) THEN
         INFO = -4
      ELSE IF( LDT .LT. MAX( 1, N ) ) THEN
         INFO = -6
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGEQRT3', -INFO )
         RETURN
      END IF
*
      IF( N.EQ.1 ) THEN
*
*        Compute Householder transform when N=1
*
         CALL DLARFG( M, A(1,1), A( MIN( 2, M ), 1 ), 1, T(1,1) )
*
      ELSE
*
*        Otherwise, split A into blocks...
*
         N1 = N/2
         N2 = N-N1
         J1 = MIN( N1+1, N )
         I1 = MIN( N+1, M )
*
*        Compute A(1:M,1:N1) <- (Y1,R1,T1), where Q1 = I - Y1 T1 Y1^H
*
         CALL DGEQRT3( M, N1, A, LDA, T, LDT, IINFO )
*
*        Compute A(1:M,J1:N) = Q1^H A(1:M,J1:N) [workspace: T(1:N1,J1:N)]
*
         DO J=1,N2
            DO I=1,N1
               T( I, J+N1 ) = A( I, J+N1 )
            END DO
         END DO
         CALL DTRMM( 'L', 'L', 'T', 'U', N1, N2, ONE,
     &               A, LDA, T( 1, J1 ), LDT )
*
         CALL DGEMM( 'T', 'N', N1, N2, M-N1, ONE, A( J1, 1 ), LDA,
     &               A( J1, J1 ), LDA, ONE, T( 1, J1 ), LDT)
*
         CALL DTRMM( 'L', 'U', 'T', 'N', N1, N2, ONE,
     &               T, LDT, T( 1, J1 ), LDT )
*
         CALL DGEMM( 'N', 'N', M-N1, N2, N1, -ONE, A( J1, 1 ), LDA,
     &               T( 1, J1 ), LDT, ONE, A( J1, J1 ), LDA )
*
         CALL DTRMM( 'L', 'L', 'N', 'U', N1, N2, ONE,
     &               A, LDA, T( 1, J1 ), LDT )
*
         DO J=1,N2
            DO I=1,N1
               A( I, J+N1 ) = A( I, J+N1 ) - T( I, J+N1 )
            END DO
         END DO
*
*        Compute A(J1:M,J1:N) <- (Y2,R2,T2) where Q2 = I - Y2 T2 Y2^H
*
         CALL DGEQRT3( M-N1, N2, A( J1, J1 ), LDA,
     &                T( J1, J1 ), LDT, IINFO )
*
*        Compute T3 = T(1:N1,J1:N) = -T1 Y1^H Y2 T2
*
         DO I=1,N1
            DO J=1,N2
               T( I, J+N1 ) = (A( J+N1, I ))
            END DO
         END DO
*
         CALL DTRMM( 'R', 'L', 'N', 'U', N1, N2, ONE,
     &               A( J1, J1 ), LDA, T( 1, J1 ), LDT )
*
         CALL DGEMM( 'T', 'N', N1, N2, M-N, ONE, A( I1, 1 ), LDA,
     &               A( I1, J1 ), LDA, ONE, T( 1, J1 ), LDT )
*
         CALL DTRMM( 'L', 'U', 'N', 'N', N1, N2, -ONE, T, LDT,
     &               T( 1, J1 ), LDT )
*
         CALL DTRMM( 'R', 'U', 'N', 'N', N1, N2, ONE,
     &               T( J1, J1 ), LDT, T( 1, J1 ), LDT )
*
*        Y = (Y1,Y2); R = [ R1  A(1:N1,J1:N) ];  T = [T1 T3]
*                         [  0        R2     ]       [ 0 T2]
*
      END IF
*
      RETURN
*
*     End of DGEQRT3
*
      END
*> \brief \b DGERFS
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGERFS + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgerfs.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgerfs.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgerfs.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGERFS( TRANS, N, NRHS, A, LDA, AF, LDAF, IPIV, B, LDB,
*                          X, LDX, FERR, BERR, WORK, IWORK, INFO )
*
*       .. Scalar Arguments ..
*       CHARACTER          TRANS
*       INTEGER            INFO, LDA, LDAF, LDB, LDX, N, NRHS
*       ..
*       .. Array Arguments ..
*       INTEGER            IPIV( * ), IWORK( * )
*       DOUBLE PRECISION   A( LDA, * ), AF( LDAF, * ), B( LDB, * ),
*      $                   BERR( * ), FERR( * ), WORK( * ), X( LDX, * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGERFS improves the computed solution to a system of linear
*> equations and provides error bounds and backward error estimates for
*> the solution.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] TRANS
*> \verbatim
*>          TRANS is CHARACTER*1
*>          Specifies the form of the system of equations:
*>          = 'N':  A * X = B     (No transpose)
*>          = 'T':  A**T * X = B  (Transpose)
*>          = 'C':  A**H * X = B  (Conjugate transpose = Transpose)
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The order of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in] NRHS
*> \verbatim
*>          NRHS is INTEGER
*>          The number of right hand sides, i.e., the number of columns
*>          of the matrices B and X.  NRHS >= 0.
*> \endverbatim
*>
*> \param[in] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          The original N-by-N matrix A.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,N).
*> \endverbatim
*>
*> \param[in] AF
*> \verbatim
*>          AF is DOUBLE PRECISION array, dimension (LDAF,N)
*>          The factors L and U from the factorization A = P*L*U
*>          as computed by DGETRF.
*> \endverbatim
*>
*> \param[in] LDAF
*> \verbatim
*>          LDAF is INTEGER
*>          The leading dimension of the array AF.  LDAF >= max(1,N).
*> \endverbatim
*>
*> \param[in] IPIV
*> \verbatim
*>          IPIV is INTEGER array, dimension (N)
*>          The pivot indices from DGETRF; for 1<=i<=N, row i of the
*>          matrix was interchanged with row IPIV(i).
*> \endverbatim
*>
*> \param[in] B
*> \verbatim
*>          B is DOUBLE PRECISION array, dimension (LDB,NRHS)
*>          The right hand side matrix B.
*> \endverbatim
*>
*> \param[in] LDB
*> \verbatim
*>          LDB is INTEGER
*>          The leading dimension of the array B.  LDB >= max(1,N).
*> \endverbatim
*>
*> \param[in,out] X
*> \verbatim
*>          X is DOUBLE PRECISION array, dimension (LDX,NRHS)
*>          On entry, the solution matrix X, as computed by DGETRS.
*>          On exit, the improved solution matrix X.
*> \endverbatim
*>
*> \param[in] LDX
*> \verbatim
*>          LDX is INTEGER
*>          The leading dimension of the array X.  LDX >= max(1,N).
*> \endverbatim
*>
*> \param[out] FERR
*> \verbatim
*>          FERR is DOUBLE PRECISION array, dimension (NRHS)
*>          The estimated forward error bound for each solution vector
*>          X(j) (the j-th column of the solution matrix X).
*>          If XTRUE is the true solution corresponding to X(j), FERR(j)
*>          is an estimated upper bound for the magnitude of the largest
*>          element in (X(j) - XTRUE) divided by the magnitude of the
*>          largest element in X(j).  The estimate is as reliable as
*>          the estimate for RCOND, and is almost always a slight
*>          overestimate of the true error.
*> \endverbatim
*>
*> \param[out] BERR
*> \verbatim
*>          BERR is DOUBLE PRECISION array, dimension (NRHS)
*>          The componentwise relative backward error of each solution
*>          vector X(j) (i.e., the smallest relative change in
*>          any element of A or B that makes X(j) an exact solution).
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (3*N)
*> \endverbatim
*>
*> \param[out] IWORK
*> \verbatim
*>          IWORK is INTEGER array, dimension (N)
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value
*> \endverbatim
*
*> \par Internal Parameters:
*  =========================
*>
*> \verbatim
*>  ITMAX is the maximum number of steps of iterative refinement.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEcomputational
*
*  =====================================================================
      SUBROUTINE DGERFS( TRANS, N, NRHS, A, LDA, AF, LDAF, IPIV, B, LDB,
     $                   X, LDX, FERR, BERR, WORK, IWORK, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      CHARACTER          TRANS
      INTEGER            INFO, LDA, LDAF, LDB, LDX, N, NRHS
*     ..
*     .. Array Arguments ..
      INTEGER            IPIV( * ), IWORK( * )
      DOUBLE PRECISION   A( LDA, * ), AF( LDAF, * ), B( LDB, * ),
     $                   BERR( * ), FERR( * ), WORK( * ), X( LDX, * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      INTEGER            ITMAX
      PARAMETER          ( ITMAX = 5 )
      DOUBLE PRECISION   ZERO
      PARAMETER          ( ZERO = 0.0D+0 )
      DOUBLE PRECISION   ONE
      PARAMETER          ( ONE = 1.0D+0 )
      DOUBLE PRECISION   TWO
      PARAMETER          ( TWO = 2.0D+0 )
      DOUBLE PRECISION   THREE
      PARAMETER          ( THREE = 3.0D+0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            NOTRAN
      CHARACTER          TRANST
      INTEGER            COUNT, I, J, K, KASE, NZ
      DOUBLE PRECISION   EPS, LSTRES, S, SAFE1, SAFE2, SAFMIN, XK
*     ..
*     .. Local Arrays ..
      INTEGER            ISAVE( 3 )
*     ..
*     .. External Subroutines ..
      EXTERNAL           DAXPY, DCOPY, DGEMV, DGETRS, DLACN2, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          ABS, MAX
*     ..
*     .. External Functions ..
      LOGICAL            LSAME
      DOUBLE PRECISION   DLAMCH
      EXTERNAL           LSAME, DLAMCH
*     ..
*     .. Executable Statements ..
*
*     Test the input parameters.
*
      INFO = 0
      NOTRAN = LSAME( TRANS, 'N' )
      IF( .NOT.NOTRAN .AND. .NOT.LSAME( TRANS, 'T' ) .AND. .NOT.
     $    LSAME( TRANS, 'C' ) ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( NRHS.LT.0 ) THEN
         INFO = -3
      ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
         INFO = -5
      ELSE IF( LDAF.LT.MAX( 1, N ) ) THEN
         INFO = -7
      ELSE IF( LDB.LT.MAX( 1, N ) ) THEN
         INFO = -10
      ELSE IF( LDX.LT.MAX( 1, N ) ) THEN
         INFO = -12
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGERFS', -INFO )
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( N.EQ.0 .OR. NRHS.EQ.0 ) THEN
         DO 10 J = 1, NRHS
            FERR( J ) = ZERO
            BERR( J ) = ZERO
   10    CONTINUE
         RETURN
      END IF
*
      IF( NOTRAN ) THEN
         TRANST = 'T'
      ELSE
         TRANST = 'N'
      END IF
*
*     NZ = maximum number of nonzero elements in each row of A, plus 1
*
      NZ = N + 1
      EPS = DLAMCH( 'Epsilon' )
      SAFMIN = DLAMCH( 'Safe minimum' )
      SAFE1 = NZ*SAFMIN
      SAFE2 = SAFE1 / EPS
*
*     Do for each right hand side
*
      DO 140 J = 1, NRHS
*
         COUNT = 1
         LSTRES = THREE
   20    CONTINUE
*
*        Loop until stopping criterion is satisfied.
*
*        Compute residual R = B - op(A) * X,
*        where op(A) = A, A**T, or A**H, depending on TRANS.
*
         CALL DCOPY( N, B( 1, J ), 1, WORK( N+1 ), 1 )
         CALL DGEMV( TRANS, N, N, -ONE, A, LDA, X( 1, J ), 1, ONE,
     $               WORK( N+1 ), 1 )
*
*        Compute componentwise relative backward error from formula
*
*        max(i) ( abs(R(i)) / ( abs(op(A))*abs(X) + abs(B) )(i) )
*
*        where abs(Z) is the componentwise absolute value of the matrix
*        or vector Z.  If the i-th component of the denominator is less
*        than SAFE2, then SAFE1 is added to the i-th components of the
*        numerator and denominator before dividing.
*
         DO 30 I = 1, N
            WORK( I ) = ABS( B( I, J ) )
   30    CONTINUE
*
*        Compute abs(op(A))*abs(X) + abs(B).
*
         IF( NOTRAN ) THEN
            DO 50 K = 1, N
               XK = ABS( X( K, J ) )
               DO 40 I = 1, N
                  WORK( I ) = WORK( I ) + ABS( A( I, K ) )*XK
   40          CONTINUE
   50       CONTINUE
         ELSE
            DO 70 K = 1, N
               S = ZERO
               DO 60 I = 1, N
                  S = S + ABS( A( I, K ) )*ABS( X( I, J ) )
   60          CONTINUE
               WORK( K ) = WORK( K ) + S
   70       CONTINUE
         END IF
         S = ZERO
         DO 80 I = 1, N
            IF( WORK( I ).GT.SAFE2 ) THEN
               S = MAX( S, ABS( WORK( N+I ) ) / WORK( I ) )
            ELSE
               S = MAX( S, ( ABS( WORK( N+I ) )+SAFE1 ) /
     $             ( WORK( I )+SAFE1 ) )
            END IF
   80    CONTINUE
         BERR( J ) = S
*
*        Test stopping criterion. Continue iterating if
*           1) The residual BERR(J) is larger than machine epsilon, and
*           2) BERR(J) decreased by at least a factor of 2 during the
*              last iteration, and
*           3) At most ITMAX iterations tried.
*
         IF( BERR( J ).GT.EPS .AND. TWO*BERR( J ).LE.LSTRES .AND.
     $       COUNT.LE.ITMAX ) THEN
*
*           Update solution and try again.
*
            CALL DGETRS( TRANS, N, 1, AF, LDAF, IPIV, WORK( N+1 ), N,
     $                   INFO )
            CALL DAXPY( N, ONE, WORK( N+1 ), 1, X( 1, J ), 1 )
            LSTRES = BERR( J )
            COUNT = COUNT + 1
            GO TO 20
         END IF
*
*        Bound error from formula
*
*        norm(X - XTRUE) / norm(X) .le. FERR =
*        norm( abs(inv(op(A)))*
*           ( abs(R) + NZ*EPS*( abs(op(A))*abs(X)+abs(B) ))) / norm(X)
*
*        where
*          norm(Z) is the magnitude of the largest component of Z
*          inv(op(A)) is the inverse of op(A)
*          abs(Z) is the componentwise absolute value of the matrix or
*             vector Z
*          NZ is the maximum number of nonzeros in any row of A, plus 1
*          EPS is machine epsilon
*
*        The i-th component of abs(R)+NZ*EPS*(abs(op(A))*abs(X)+abs(B))
*        is incremented by SAFE1 if the i-th component of
*        abs(op(A))*abs(X) + abs(B) is less than SAFE2.
*
*        Use DLACN2 to estimate the infinity-norm of the matrix
*           inv(op(A)) * diag(W),
*        where W = abs(R) + NZ*EPS*( abs(op(A))*abs(X)+abs(B) )))
*
         DO 90 I = 1, N
            IF( WORK( I ).GT.SAFE2 ) THEN
               WORK( I ) = ABS( WORK( N+I ) ) + NZ*EPS*WORK( I )
            ELSE
               WORK( I ) = ABS( WORK( N+I ) ) + NZ*EPS*WORK( I ) + SAFE1
            END IF
   90    CONTINUE
*
         KASE = 0
  100    CONTINUE
         CALL DLACN2( N, WORK( 2*N+1 ), WORK( N+1 ), IWORK, FERR( J ),
     $                KASE, ISAVE )
         IF( KASE.NE.0 ) THEN
            IF( KASE.EQ.1 ) THEN
*
*              Multiply by diag(W)*inv(op(A)**T).
*
               CALL DGETRS( TRANST, N, 1, AF, LDAF, IPIV, WORK( N+1 ),
     $                      N, INFO )
               DO 110 I = 1, N
                  WORK( N+I ) = WORK( I )*WORK( N+I )
  110          CONTINUE
            ELSE
*
*              Multiply by inv(op(A))*diag(W).
*
               DO 120 I = 1, N
                  WORK( N+I ) = WORK( I )*WORK( N+I )
  120          CONTINUE
               CALL DGETRS( TRANS, N, 1, AF, LDAF, IPIV, WORK( N+1 ), N,
     $                      INFO )
            END IF
            GO TO 100
         END IF
*
*        Normalize error.
*
         LSTRES = ZERO
         DO 130 I = 1, N
            LSTRES = MAX( LSTRES, ABS( X( I, J ) ) )
  130    CONTINUE
         IF( LSTRES.NE.ZERO )
     $      FERR( J ) = FERR( J ) / LSTRES
*
  140 CONTINUE
*
      RETURN
*
*     End of DGERFS
*
      END
*> \brief \b DGERQ2 computes the RQ factorization of a general rectangular matrix using an unblocked algorithm.
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGERQ2 + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgerq2.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgerq2.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgerq2.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGERQ2( M, N, A, LDA, TAU, WORK, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, LDA, M, N
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGERQ2 computes an RQ factorization of a real m by n matrix A:
*> A = R * Q.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A.  M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the m by n matrix A.
*>          On exit, if m <= n, the upper triangle of the subarray
*>          A(1:m,n-m+1:n) contains the m by m upper triangular matrix R;
*>          if m >= n, the elements on and above the (m-n)-th subdiagonal
*>          contain the m by n upper trapezoidal matrix R; the remaining
*>          elements, with the array TAU, represent the orthogonal matrix
*>          Q as a product of elementary reflectors (see Further
*>          Details).
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,M).
*> \endverbatim
*>
*> \param[out] TAU
*> \verbatim
*>          TAU is DOUBLE PRECISION array, dimension (min(M,N))
*>          The scalar factors of the elementary reflectors (see Further
*>          Details).
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (M)
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0: successful exit
*>          < 0: if INFO = -i, the i-th argument had an illegal value
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEcomputational
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>  The matrix Q is represented as a product of elementary reflectors
*>
*>     Q = H(1) H(2) . . . H(k), where k = min(m,n).
*>
*>  Each H(i) has the form
*>
*>     H(i) = I - tau * v * v**T
*>
*>  where tau is a real scalar, and v is a real vector with
*>  v(n-k+i+1:n) = 0 and v(n-k+i) = 1; v(1:n-k+i-1) is stored on exit in
*>  A(m-k+i,1:n-k+i-1), and tau in TAU(i).
*> \endverbatim
*>
*  =====================================================================
      SUBROUTINE DGERQ2( M, N, A, LDA, TAU, WORK, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER            INFO, LDA, M, N
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ONE
      PARAMETER          ( ONE = 1.0D+0 )
*     ..
*     .. Local Scalars ..
      INTEGER            I, K
      DOUBLE PRECISION   AII
*     ..
*     .. External Subroutines ..
      EXTERNAL           DLARF, DLARFG, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, MIN
*     ..
*     .. Executable Statements ..
*
*     Test the input arguments
*
      INFO = 0
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -4
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGERQ2', -INFO )
         RETURN
      END IF
*
      K = MIN( M, N )
*
      DO 10 I = K, 1, -1
*
*        Generate elementary reflector H(i) to annihilate
*        A(m-k+i,1:n-k+i-1)
*
         CALL DLARFG( N-K+I, A( M-K+I, N-K+I ), A( M-K+I, 1 ), LDA,
     $                TAU( I ) )
*
*        Apply H(i) to A(1:m-k+i-1,1:n-k+i) from the right
*
         AII = A( M-K+I, N-K+I )
         A( M-K+I, N-K+I ) = ONE
         CALL DLARF( 'Right', M-K+I-1, N-K+I, A( M-K+I, 1 ), LDA,
     $               TAU( I ), A, LDA, WORK )
         A( M-K+I, N-K+I ) = AII
   10 CONTINUE
      RETURN
*
*     End of DGERQ2
*
      END
*> \brief \b DGERQF
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGERQF + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgerqf.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgerqf.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgerqf.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGERQF( M, N, A, LDA, TAU, WORK, LWORK, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, LDA, LWORK, M, N
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGERQF computes an RQ factorization of a real M-by-N matrix A:
*> A = R * Q.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A.  M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the M-by-N matrix A.
*>          On exit,
*>          if m <= n, the upper triangle of the subarray
*>          A(1:m,n-m+1:n) contains the M-by-M upper triangular matrix R;
*>          if m >= n, the elements on and above the (m-n)-th subdiagonal
*>          contain the M-by-N upper trapezoidal matrix R;
*>          the remaining elements, with the array TAU, represent the
*>          orthogonal matrix Q as a product of min(m,n) elementary
*>          reflectors (see Further Details).
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,M).
*> \endverbatim
*>
*> \param[out] TAU
*> \verbatim
*>          TAU is DOUBLE PRECISION array, dimension (min(M,N))
*>          The scalar factors of the elementary reflectors (see Further
*>          Details).
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK))
*>          On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
*> \endverbatim
*>
*> \param[in] LWORK
*> \verbatim
*>          LWORK is INTEGER
*>          The dimension of the array WORK.  LWORK >= max(1,M).
*>          For optimum performance LWORK >= M*NB, where NB is
*>          the optimal blocksize.
*>
*>          If LWORK = -1, then a workspace query is assumed; the routine
*>          only calculates the optimal size of the WORK array, returns
*>          this value as the first entry of the WORK array, and no error
*>          message related to LWORK is issued by XERBLA.
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEcomputational
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>  The matrix Q is represented as a product of elementary reflectors
*>
*>     Q = H(1) H(2) . . . H(k), where k = min(m,n).
*>
*>  Each H(i) has the form
*>
*>     H(i) = I - tau * v * v**T
*>
*>  where tau is a real scalar, and v is a real vector with
*>  v(n-k+i+1:n) = 0 and v(n-k+i) = 1; v(1:n-k+i-1) is stored on exit in
*>  A(m-k+i,1:n-k+i-1), and tau in TAU(i).
*> \endverbatim
*>
*  =====================================================================
      SUBROUTINE DGERQF( M, N, A, LDA, TAU, WORK, LWORK, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER            INFO, LDA, LWORK, M, N
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Local Scalars ..
      LOGICAL            LQUERY
      INTEGER            I, IB, IINFO, IWS, K, KI, KK, LDWORK, LWKOPT,
     $                   MU, NB, NBMIN, NU, NX
*     ..
*     .. External Subroutines ..
      EXTERNAL           DGERQ2, DLARFB, DLARFT, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, MIN
*     ..
*     .. External Functions ..
      INTEGER            ILAENV
      EXTERNAL           ILAENV
*     ..
*     .. Executable Statements ..
*
*     Test the input arguments
*
      INFO = 0
      LQUERY = ( LWORK.EQ.-1 )
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -4
      END IF
*
      IF( INFO.EQ.0 ) THEN
         K = MIN( M, N )
         IF( K.EQ.0 ) THEN
            LWKOPT = 1
         ELSE
            NB = ILAENV( 1, 'DGERQF', ' ', M, N, -1, -1 )
            LWKOPT = M*NB
         END IF
         WORK( 1 ) = LWKOPT
*
         IF( LWORK.LT.MAX( 1, M ) .AND. .NOT.LQUERY ) THEN
            INFO = -7
         END IF
      END IF
*
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGERQF', -INFO )
         RETURN
      ELSE IF( LQUERY ) THEN
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( K.EQ.0 ) THEN
         RETURN
      END IF
*
      NBMIN = 2
      NX = 1
      IWS = M
      IF( NB.GT.1 .AND. NB.LT.K ) THEN
*
*        Determine when to cross over from blocked to unblocked code.
*
         NX = MAX( 0, ILAENV( 3, 'DGERQF', ' ', M, N, -1, -1 ) )
         IF( NX.LT.K ) THEN
*
*           Determine if workspace is large enough for blocked code.
*
            LDWORK = M
            IWS = LDWORK*NB
            IF( LWORK.LT.IWS ) THEN
*
*              Not enough workspace to use optimal NB:  reduce NB and
*              determine the minimum value of NB.
*
               NB = LWORK / LDWORK
               NBMIN = MAX( 2, ILAENV( 2, 'DGERQF', ' ', M, N, -1,
     $                 -1 ) )
            END IF
         END IF
      END IF
*
      IF( NB.GE.NBMIN .AND. NB.LT.K .AND. NX.LT.K ) THEN
*
*        Use blocked code initially.
*        The last kk rows are handled by the block method.
*
         KI = ( ( K-NX-1 ) / NB )*NB
         KK = MIN( K, KI+NB )
*
         DO 10 I = K - KK + KI + 1, K - KK + 1, -NB
            IB = MIN( K-I+1, NB )
*
*           Compute the RQ factorization of the current block
*           A(m-k+i:m-k+i+ib-1,1:n-k+i+ib-1)
*
            CALL DGERQ2( IB, N-K+I+IB-1, A( M-K+I, 1 ), LDA, TAU( I ),
     $                   WORK, IINFO )
            IF( M-K+I.GT.1 ) THEN
*
*              Form the triangular factor of the block reflector
*              H = H(i+ib-1) . . . H(i+1) H(i)
*
               CALL DLARFT( 'Backward', 'Rowwise', N-K+I+IB-1, IB,
     $                      A( M-K+I, 1 ), LDA, TAU( I ), WORK, LDWORK )
*
*              Apply H to A(1:m-k+i-1,1:n-k+i+ib-1) from the right
*
               CALL DLARFB( 'Right', 'No transpose', 'Backward',
     $                      'Rowwise', M-K+I-1, N-K+I+IB-1, IB,
     $                      A( M-K+I, 1 ), LDA, WORK, LDWORK, A, LDA,
     $                      WORK( IB+1 ), LDWORK )
            END IF
   10    CONTINUE
         MU = M - K + I + NB - 1
         NU = N - K + I + NB - 1
      ELSE
         MU = M
         NU = N
      END IF
*
*     Use unblocked code to factor the last or only block
*
      IF( MU.GT.0 .AND. NU.GT.0 )
     $   CALL DGERQ2( MU, NU, A, LDA, TAU, WORK, IINFO )
*
      WORK( 1 ) = IWS
      RETURN
*
*     End of DGERQF
*
      END
*> \brief \b DGESC2 solves a system of linear equations using the LU factorization with complete pivoting computed by sgetc2.
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGESC2 + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgesc2.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgesc2.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgesc2.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGESC2( N, A, LDA, RHS, IPIV, JPIV, SCALE )
*
*       .. Scalar Arguments ..
*       INTEGER            LDA, N
*       DOUBLE PRECISION   SCALE
*       ..
*       .. Array Arguments ..
*       INTEGER            IPIV( * ), JPIV( * )
*       DOUBLE PRECISION   A( LDA, * ), RHS( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGESC2 solves a system of linear equations
*>
*>           A * X = scale* RHS
*>
*> with a general N-by-N matrix A using the LU factorization with
*> complete pivoting computed by DGETC2.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The order of the matrix A.
*> \endverbatim
*>
*> \param[in] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the  LU part of the factorization of the n-by-n
*>          matrix A computed by DGETC2:  A = P * L * U * Q
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1, N).
*> \endverbatim
*>
*> \param[in,out] RHS
*> \verbatim
*>          RHS is DOUBLE PRECISION array, dimension (N).
*>          On entry, the right hand side vector b.
*>          On exit, the solution vector X.
*> \endverbatim
*>
*> \param[in] IPIV
*> \verbatim
*>          IPIV is INTEGER array, dimension (N).
*>          The pivot indices; for 1 <= i <= N, row i of the
*>          matrix has been interchanged with row IPIV(i).
*> \endverbatim
*>
*> \param[in] JPIV
*> \verbatim
*>          JPIV is INTEGER array, dimension (N).
*>          The pivot indices; for 1 <= j <= N, column j of the
*>          matrix has been interchanged with column JPIV(j).
*> \endverbatim
*>
*> \param[out] SCALE
*> \verbatim
*>          SCALE is DOUBLE PRECISION
*>          On exit, SCALE contains the scale factor. SCALE is chosen
*>          0 <= SCALE <= 1 to prevent owerflow in the solution.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date November 2017
*
*> \ingroup doubleGEauxiliary
*
*> \par Contributors:
*  ==================
*>
*>     Bo Kagstrom and Peter Poromaa, Department of Computing Science,
*>     Umea University, S-901 87 Umea, Sweden.
*
*  =====================================================================
      SUBROUTINE DGESC2( N, A, LDA, RHS, IPIV, JPIV, SCALE )
*
*  -- LAPACK auxiliary routine (version 3.8.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     November 2017
*
*     .. Scalar Arguments ..
      INTEGER            LDA, N
      DOUBLE PRECISION   SCALE
*     ..
*     .. Array Arguments ..
      INTEGER            IPIV( * ), JPIV( * )
      DOUBLE PRECISION   A( LDA, * ), RHS( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ONE, TWO
      PARAMETER          ( ONE = 1.0D+0, TWO = 2.0D+0 )
*     ..
*     .. Local Scalars ..
      INTEGER            I, J
      DOUBLE PRECISION   BIGNUM, EPS, SMLNUM, TEMP
*     ..
*     .. External Subroutines ..
      EXTERNAL           DLASWP, DSCAL, DLABAD
*     ..
*     .. External Functions ..
      INTEGER            IDAMAX
      DOUBLE PRECISION   DLAMCH
      EXTERNAL           IDAMAX, DLAMCH
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          ABS
*     ..
*     .. Executable Statements ..
*
*      Set constant to control owerflow
*
      EPS = DLAMCH( 'P' )
      SMLNUM = DLAMCH( 'S' ) / EPS
      BIGNUM = ONE / SMLNUM
      CALL DLABAD( SMLNUM, BIGNUM )
*
*     Apply permutations IPIV to RHS
*
      CALL DLASWP( 1, RHS, LDA, 1, N-1, IPIV, 1 )
*
*     Solve for L part
*
      DO 20 I = 1, N - 1
         DO 10 J = I + 1, N
            RHS( J ) = RHS( J ) - A( J, I )*RHS( I )
   10    CONTINUE
   20 CONTINUE
*
*     Solve for U part
*
      SCALE = ONE
*
*     Check for scaling
*
      I = IDAMAX( N, RHS, 1 )
      IF( TWO*SMLNUM*ABS( RHS( I ) ).GT.ABS( A( N, N ) ) ) THEN
         TEMP = ( ONE / TWO ) / ABS( RHS( I ) )
         CALL DSCAL( N, TEMP, RHS( 1 ), 1 )
         SCALE = SCALE*TEMP
      END IF
*
      DO 40 I = N, 1, -1
         TEMP = ONE / A( I, I )
         RHS( I ) = RHS( I )*TEMP
         DO 30 J = I + 1, N
            RHS( I ) = RHS( I ) - RHS( J )*( A( I, J )*TEMP )
   30    CONTINUE
   40 CONTINUE
*
*     Apply permutations JPIV to the solution (RHS)
*
      CALL DLASWP( 1, RHS, LDA, 1, N-1, JPIV, -1 )
      RETURN
*
*     End of DGESC2
*
      END
*> \brief \b DGESDD
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGESDD + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgesdd.f">
*> [TGZ]</a>
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*
*  Definition:
*  ===========
*
*       SUBROUTINE DGESDD( JOBZ, M, N, A, LDA, S, U, LDU, VT, LDVT,
*                          WORK, LWORK, IWORK, INFO )
*
*       .. Scalar Arguments ..
*       CHARACTER          JOBZ
*       INTEGER            INFO, LDA, LDU, LDVT, LWORK, M, N
*       ..
*       .. Array Arguments ..
*       INTEGER            IWORK( * )
*       DOUBLE PRECISION   A( LDA, * ), S( * ), U( LDU, * ),
*      $                   VT( LDVT, * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGESDD computes the singular value decomposition (SVD) of a real
*> M-by-N matrix A, optionally computing the left and right singular
*> vectors.  If singular vectors are desired, it uses a
*> divide-and-conquer algorithm.
*>
*> The SVD is written
*>
*>      A = U * SIGMA * transpose(V)
*>
*> where SIGMA is an M-by-N matrix which is zero except for its
*> min(m,n) diagonal elements, U is an M-by-M orthogonal matrix, and
*> V is an N-by-N orthogonal matrix.  The diagonal elements of SIGMA
*> are the singular values of A; they are real and non-negative, and
*> are returned in descending order.  The first min(m,n) columns of
*> U and V are the left and right singular vectors of A.
*>
*> Note that the routine returns VT = V**T, not V.
*>
*> The divide and conquer algorithm makes very mild assumptions about
*> floating point arithmetic. It will work on machines with a guard
*> digit in add/subtract, or on those binary machines without guard
*> digits which subtract like the Cray X-MP, Cray Y-MP, Cray C-90, or
*> Cray-2. It could conceivably fail on hexadecimal or decimal machines
*> without guard digits, but we know of none.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] JOBZ
*> \verbatim
*>          JOBZ is CHARACTER*1
*>          Specifies options for computing all or part of the matrix U:
*>          = 'A':  all M columns of U and all N rows of V**T are
*>                  returned in the arrays U and VT;
*>          = 'S':  the first min(M,N) columns of U and the first
*>                  min(M,N) rows of V**T are returned in the arrays U
*>                  and VT;
*>          = 'O':  If M >= N, the first N columns of U are overwritten
*>                  on the array A and all rows of V**T are returned in
*>                  the array VT;
*>                  otherwise, all columns of U are returned in the
*>                  array U and the first M rows of V**T are overwritten
*>                  in the array A;
*>          = 'N':  no columns of U or rows of V**T are computed.
*> \endverbatim
*>
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the input matrix A.  M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the input matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the M-by-N matrix A.
*>          On exit,
*>          if JOBZ = 'O',  A is overwritten with the first N columns
*>                          of U (the left singular vectors, stored
*>                          columnwise) if M >= N;
*>                          A is overwritten with the first M rows
*>                          of V**T (the right singular vectors, stored
*>                          rowwise) otherwise.
*>          if JOBZ .ne. 'O', the contents of A are destroyed.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,M).
*> \endverbatim
*>
*> \param[out] S
*> \verbatim
*>          S is DOUBLE PRECISION array, dimension (min(M,N))
*>          The singular values of A, sorted so that S(i) >= S(i+1).
*> \endverbatim
*>
*> \param[out] U
*> \verbatim
*>          U is DOUBLE PRECISION array, dimension (LDU,UCOL)
*>          UCOL = M if JOBZ = 'A' or JOBZ = 'O' and M < N;
*>          UCOL = min(M,N) if JOBZ = 'S'.
*>          If JOBZ = 'A' or JOBZ = 'O' and M < N, U contains the M-by-M
*>          orthogonal matrix U;
*>          if JOBZ = 'S', U contains the first min(M,N) columns of U
*>          (the left singular vectors, stored columnwise);
*>          if JOBZ = 'O' and M >= N, or JOBZ = 'N', U is not referenced.
*> \endverbatim
*>
*> \param[in] LDU
*> \verbatim
*>          LDU is INTEGER
*>          The leading dimension of the array U.  LDU >= 1; if
*>          JOBZ = 'S' or 'A' or JOBZ = 'O' and M < N, LDU >= M.
*> \endverbatim
*>
*> \param[out] VT
*> \verbatim
*>          VT is DOUBLE PRECISION array, dimension (LDVT,N)
*>          If JOBZ = 'A' or JOBZ = 'O' and M >= N, VT contains the
*>          N-by-N orthogonal matrix V**T;
*>          if JOBZ = 'S', VT contains the first min(M,N) rows of
*>          V**T (the right singular vectors, stored rowwise);
*>          if JOBZ = 'O' and M < N, or JOBZ = 'N', VT is not referenced.
*> \endverbatim
*>
*> \param[in] LDVT
*> \verbatim
*>          LDVT is INTEGER
*>          The leading dimension of the array VT.  LDVT >= 1;
*>          if JOBZ = 'A' or JOBZ = 'O' and M >= N, LDVT >= N;
*>          if JOBZ = 'S', LDVT >= min(M,N).
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK))
*>          On exit, if INFO = 0, WORK(1) returns the optimal LWORK;
*> \endverbatim
*>
*> \param[in] LWORK
*> \verbatim
*>          LWORK is INTEGER
*>          The dimension of the array WORK. LWORK >= 1.
*>          If LWORK = -1, a workspace query is assumed.  The optimal
*>          size for the WORK array is calculated and stored in WORK(1),
*>          and no other work except argument checking is performed.
*>
*>          Let mx = max(M,N) and mn = min(M,N).
*>          If JOBZ = 'N', LWORK >= 3*mn + max( mx, 7*mn ).
*>          If JOBZ = 'O', LWORK >= 3*mn + max( mx, 5*mn*mn + 4*mn ).
*>          If JOBZ = 'S', LWORK >= 4*mn*mn + 7*mn.
*>          If JOBZ = 'A', LWORK >= 4*mn*mn + 6*mn + mx.
*>          These are not tight minimums in all cases; see comments inside code.
*>          For good performance, LWORK should generally be larger;
*>          a query is recommended.
*> \endverbatim
*>
*> \param[out] IWORK
*> \verbatim
*>          IWORK is INTEGER array, dimension (8*min(M,N))
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit.
*>          < 0:  if INFO = -i, the i-th argument had an illegal value.
*>          > 0:  DBDSDC did not converge, updating process failed.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date June 2016
*
*> \ingroup doubleGEsing
*
*> \par Contributors:
*  ==================
*>
*>     Ming Gu and Huan Ren, Computer Science Division, University of
*>     California at Berkeley, USA
*>
*  =====================================================================
      SUBROUTINE DGESDD( JOBZ, M, N, A, LDA, S, U, LDU, VT, LDVT,
     $                   WORK, LWORK, IWORK, INFO )
      implicit none
*
*  -- LAPACK driver routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     June 2016
*
*     .. Scalar Arguments ..
      CHARACTER          JOBZ
      INTEGER            INFO, LDA, LDU, LDVT, LWORK, M, N
*     ..
*     .. Array Arguments ..
      INTEGER            IWORK( * )
      DOUBLE PRECISION   A( LDA, * ), S( * ), U( LDU, * ),
     $                   VT( LDVT, * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ZERO, ONE
      PARAMETER          ( ZERO = 0.0D0, ONE = 1.0D0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            LQUERY, WNTQA, WNTQAS, WNTQN, WNTQO, WNTQS
      INTEGER            BDSPAC, BLK, CHUNK, I, IE, IERR, IL,
     $                   IR, ISCL, ITAU, ITAUP, ITAUQ, IU, IVT, LDWKVT,
     $                   LDWRKL, LDWRKR, LDWRKU, MAXWRK, MINMN, MINWRK,
     $                   MNTHR, NWORK, WRKBL
      INTEGER            LWORK_DGEBRD_MN, LWORK_DGEBRD_MM,
     $                   LWORK_DGEBRD_NN, LWORK_DGELQF_MN,
     $                   LWORK_DGEQRF_MN,
     $                   LWORK_DORGBR_P_MM, LWORK_DORGBR_Q_NN,
     $                   LWORK_DORGLQ_MN, LWORK_DORGLQ_NN,
     $                   LWORK_DORGQR_MM, LWORK_DORGQR_MN,
     $                   LWORK_DORMBR_PRT_MM, LWORK_DORMBR_QLN_MM,
     $                   LWORK_DORMBR_PRT_MN, LWORK_DORMBR_QLN_MN,
     $                   LWORK_DORMBR_PRT_NN, LWORK_DORMBR_QLN_NN
      DOUBLE PRECISION   ANRM, BIGNUM, EPS, SMLNUM
*     ..
*     .. Local Arrays ..
      INTEGER            IDUM( 1 )
      DOUBLE PRECISION   DUM( 1 )
*     ..
*     .. External Subroutines ..
      EXTERNAL           DBDSDC, DGEBRD, DGELQF, DGEMM, DGEQRF, DLACPY,
     $                   DLASCL, DLASET, DORGBR, DORGLQ, DORGQR, DORMBR,
     $                   XERBLA
*     ..
*     .. External Functions ..
      LOGICAL            LSAME
      DOUBLE PRECISION   DLAMCH, DLANGE
      EXTERNAL           DLAMCH, DLANGE, LSAME
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          INT, MAX, MIN, SQRT
*     ..
*     .. Executable Statements ..
*
*     Test the input arguments
*
      INFO   = 0
      MINMN  = MIN( M, N )
      WNTQA  = LSAME( JOBZ, 'A' )
      WNTQS  = LSAME( JOBZ, 'S' )
      WNTQAS = WNTQA .OR. WNTQS
      WNTQO  = LSAME( JOBZ, 'O' )
      WNTQN  = LSAME( JOBZ, 'N' )
      LQUERY = ( LWORK.EQ.-1 )
*
      IF( .NOT.( WNTQA .OR. WNTQS .OR. WNTQO .OR. WNTQN ) ) THEN
         INFO = -1
      ELSE IF( M.LT.0 ) THEN
         INFO = -2
      ELSE IF( N.LT.0 ) THEN
         INFO = -3
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -5
      ELSE IF( LDU.LT.1 .OR. ( WNTQAS .AND. LDU.LT.M ) .OR.
     $         ( WNTQO .AND. M.LT.N .AND. LDU.LT.M ) ) THEN
         INFO = -8
      ELSE IF( LDVT.LT.1 .OR. ( WNTQA .AND. LDVT.LT.N ) .OR.
     $         ( WNTQS .AND. LDVT.LT.MINMN ) .OR.
     $         ( WNTQO .AND. M.GE.N .AND. LDVT.LT.N ) ) THEN
         INFO = -10
      END IF
*
*     Compute workspace
*       Note: Comments in the code beginning "Workspace:" describe the
*       minimal amount of workspace allocated at that point in the code,
*       as well as the preferred amount for good performance.
*       NB refers to the optimal block size for the immediately
*       following subroutine, as returned by ILAENV.
*
      IF( INFO.EQ.0 ) THEN
         MINWRK = 1
         MAXWRK = 1
         BDSPAC = 0
         MNTHR  = INT( MINMN*11.0D0 / 6.0D0 )
         IF( M.GE.N .AND. MINMN.GT.0 ) THEN
*
*           Compute space needed for DBDSDC
*
            IF( WNTQN ) THEN
*              dbdsdc needs only 4*N (or 6*N for uplo=L for LAPACK <= 3.6)
*              keep 7*N for backwards compatability.
               BDSPAC = 7*N
            ELSE
               BDSPAC = 3*N*N + 4*N
            END IF
*
*           Compute space preferred for each routine
            CALL DGEBRD( M, N, DUM(1), M, DUM(1), DUM(1), DUM(1),
     $                   DUM(1), DUM(1), -1, IERR )
            LWORK_DGEBRD_MN = INT( DUM(1) )
*
            CALL DGEBRD( N, N, DUM(1), N, DUM(1), DUM(1), DUM(1),
     $                   DUM(1), DUM(1), -1, IERR )
            LWORK_DGEBRD_NN = INT( DUM(1) )
*
            CALL DGEQRF( M, N, DUM(1), M, DUM(1), DUM(1), -1, IERR )
            LWORK_DGEQRF_MN = INT( DUM(1) )
*
            CALL DORGBR( 'Q', N, N, N, DUM(1), N, DUM(1), DUM(1), -1,
     $                   IERR )
            LWORK_DORGBR_Q_NN = INT( DUM(1) )
*
            CALL DORGQR( M, M, N, DUM(1), M, DUM(1), DUM(1), -1, IERR )
            LWORK_DORGQR_MM = INT( DUM(1) )
*
            CALL DORGQR( M, N, N, DUM(1), M, DUM(1), DUM(1), -1, IERR )
            LWORK_DORGQR_MN = INT( DUM(1) )
*
            CALL DORMBR( 'P', 'R', 'T', N, N, N, DUM(1), N,
     $                   DUM(1), DUM(1), N, DUM(1), -1, IERR )
            LWORK_DORMBR_PRT_NN = INT( DUM(1) )
*
            CALL DORMBR( 'Q', 'L', 'N', N, N, N, DUM(1), N,
     $                   DUM(1), DUM(1), N, DUM(1), -1, IERR )
            LWORK_DORMBR_QLN_NN = INT( DUM(1) )
*
            CALL DORMBR( 'Q', 'L', 'N', M, N, N, DUM(1), M,
     $                   DUM(1), DUM(1), M, DUM(1), -1, IERR )
            LWORK_DORMBR_QLN_MN = INT( DUM(1) )
*
            CALL DORMBR( 'Q', 'L', 'N', M, M, N, DUM(1), M,
     $                   DUM(1), DUM(1), M, DUM(1), -1, IERR )
            LWORK_DORMBR_QLN_MM = INT( DUM(1) )
*
            IF( M.GE.MNTHR ) THEN
               IF( WNTQN ) THEN
*
*                 Path 1 (M >> N, JOBZ='N')
*
                  WRKBL = N + LWORK_DGEQRF_MN
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DGEBRD_NN )
                  MAXWRK = MAX( WRKBL, BDSPAC + N )
                  MINWRK = BDSPAC + N
               ELSE IF( WNTQO ) THEN
*
*                 Path 2 (M >> N, JOBZ='O')
*
                  WRKBL = N + LWORK_DGEQRF_MN
                  WRKBL = MAX( WRKBL,   N + LWORK_DORGQR_MN )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DGEBRD_NN )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DORMBR_QLN_NN )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DORMBR_PRT_NN )
                  WRKBL = MAX( WRKBL, 3*N + BDSPAC )
                  MAXWRK = WRKBL + 2*N*N
                  MINWRK = BDSPAC + 2*N*N + 3*N
               ELSE IF( WNTQS ) THEN
*
*                 Path 3 (M >> N, JOBZ='S')
*
                  WRKBL = N + LWORK_DGEQRF_MN
                  WRKBL = MAX( WRKBL,   N + LWORK_DORGQR_MN )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DGEBRD_NN )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DORMBR_QLN_NN )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DORMBR_PRT_NN )
                  WRKBL = MAX( WRKBL, 3*N + BDSPAC )
                  MAXWRK = WRKBL + N*N
                  MINWRK = BDSPAC + N*N + 3*N
               ELSE IF( WNTQA ) THEN
*
*                 Path 4 (M >> N, JOBZ='A')
*
                  WRKBL = N + LWORK_DGEQRF_MN
                  WRKBL = MAX( WRKBL,   N + LWORK_DORGQR_MM )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DGEBRD_NN )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DORMBR_QLN_NN )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DORMBR_PRT_NN )
                  WRKBL = MAX( WRKBL, 3*N + BDSPAC )
                  MAXWRK = WRKBL + N*N
                  MINWRK = N*N + MAX( 3*N + BDSPAC, N + M )
               END IF
            ELSE
*
*              Path 5 (M >= N, but not much larger)
*
               WRKBL = 3*N + LWORK_DGEBRD_MN
               IF( WNTQN ) THEN
*                 Path 5n (M >= N, jobz='N')
                  MAXWRK = MAX( WRKBL, 3*N + BDSPAC )
                  MINWRK = 3*N + MAX( M, BDSPAC )
               ELSE IF( WNTQO ) THEN
*                 Path 5o (M >= N, jobz='O')
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DORMBR_PRT_NN )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DORMBR_QLN_MN )
                  WRKBL = MAX( WRKBL, 3*N + BDSPAC )
                  MAXWRK = WRKBL + M*N
                  MINWRK = 3*N + MAX( M, N*N + BDSPAC )
               ELSE IF( WNTQS ) THEN
*                 Path 5s (M >= N, jobz='S')
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DORMBR_QLN_MN )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DORMBR_PRT_NN )
                  MAXWRK = MAX( WRKBL, 3*N + BDSPAC )
                  MINWRK = 3*N + MAX( M, BDSPAC )
               ELSE IF( WNTQA ) THEN
*                 Path 5a (M >= N, jobz='A')
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DORMBR_QLN_MM )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DORMBR_PRT_NN )
                  MAXWRK = MAX( WRKBL, 3*N + BDSPAC )
                  MINWRK = 3*N + MAX( M, BDSPAC )
               END IF
            END IF
         ELSE IF( MINMN.GT.0 ) THEN
*
*           Compute space needed for DBDSDC
*
            IF( WNTQN ) THEN
*              dbdsdc needs only 4*N (or 6*N for uplo=L for LAPACK <= 3.6)
*              keep 7*N for backwards compatability.
               BDSPAC = 7*M
            ELSE
               BDSPAC = 3*M*M + 4*M
            END IF
*
*           Compute space preferred for each routine
            CALL DGEBRD( M, N, DUM(1), M, DUM(1), DUM(1), DUM(1),
     $                   DUM(1), DUM(1), -1, IERR )
            LWORK_DGEBRD_MN = INT( DUM(1) )
*
            CALL DGEBRD( M, M, A, M, S, DUM(1), DUM(1),
     $                   DUM(1), DUM(1), -1, IERR )
            LWORK_DGEBRD_MM = INT( DUM(1) )
*
            CALL DGELQF( M, N, A, M, DUM(1), DUM(1), -1, IERR )
            LWORK_DGELQF_MN = INT( DUM(1) )
*
            CALL DORGLQ( N, N, M, DUM(1), N, DUM(1), DUM(1), -1, IERR )
            LWORK_DORGLQ_NN = INT( DUM(1) )
*
            CALL DORGLQ( M, N, M, A, M, DUM(1), DUM(1), -1, IERR )
            LWORK_DORGLQ_MN = INT( DUM(1) )
*
            CALL DORGBR( 'P', M, M, M, A, N, DUM(1), DUM(1), -1, IERR )
            LWORK_DORGBR_P_MM = INT( DUM(1) )
*
            CALL DORMBR( 'P', 'R', 'T', M, M, M, DUM(1), M,
     $                   DUM(1), DUM(1), M, DUM(1), -1, IERR )
            LWORK_DORMBR_PRT_MM = INT( DUM(1) )
*
            CALL DORMBR( 'P', 'R', 'T', M, N, M, DUM(1), M,
     $                   DUM(1), DUM(1), M, DUM(1), -1, IERR )
            LWORK_DORMBR_PRT_MN = INT( DUM(1) )
*
            CALL DORMBR( 'P', 'R', 'T', N, N, M, DUM(1), N,
     $                   DUM(1), DUM(1), N, DUM(1), -1, IERR )
            LWORK_DORMBR_PRT_NN = INT( DUM(1) )
*
            CALL DORMBR( 'Q', 'L', 'N', M, M, M, DUM(1), M,
     $                   DUM(1), DUM(1), M, DUM(1), -1, IERR )
            LWORK_DORMBR_QLN_MM = INT( DUM(1) )
*
            IF( N.GE.MNTHR ) THEN
               IF( WNTQN ) THEN
*
*                 Path 1t (N >> M, JOBZ='N')
*
                  WRKBL = M + LWORK_DGELQF_MN
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DGEBRD_MM )
                  MAXWRK = MAX( WRKBL, BDSPAC + M )
                  MINWRK = BDSPAC + M
               ELSE IF( WNTQO ) THEN
*
*                 Path 2t (N >> M, JOBZ='O')
*
                  WRKBL = M + LWORK_DGELQF_MN
                  WRKBL = MAX( WRKBL,   M + LWORK_DORGLQ_MN )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DGEBRD_MM )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DORMBR_QLN_MM )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DORMBR_PRT_MM )
                  WRKBL = MAX( WRKBL, 3*M + BDSPAC )
                  MAXWRK = WRKBL + 2*M*M
                  MINWRK = BDSPAC + 2*M*M + 3*M
               ELSE IF( WNTQS ) THEN
*
*                 Path 3t (N >> M, JOBZ='S')
*
                  WRKBL = M + LWORK_DGELQF_MN
                  WRKBL = MAX( WRKBL,   M + LWORK_DORGLQ_MN )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DGEBRD_MM )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DORMBR_QLN_MM )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DORMBR_PRT_MM )
                  WRKBL = MAX( WRKBL, 3*M + BDSPAC )
                  MAXWRK = WRKBL + M*M
                  MINWRK = BDSPAC + M*M + 3*M
               ELSE IF( WNTQA ) THEN
*
*                 Path 4t (N >> M, JOBZ='A')
*
                  WRKBL = M + LWORK_DGELQF_MN
                  WRKBL = MAX( WRKBL,   M + LWORK_DORGLQ_NN )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DGEBRD_MM )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DORMBR_QLN_MM )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DORMBR_PRT_MM )
                  WRKBL = MAX( WRKBL, 3*M + BDSPAC )
                  MAXWRK = WRKBL + M*M
                  MINWRK = M*M + MAX( 3*M + BDSPAC, M + N )
               END IF
            ELSE
*
*              Path 5t (N > M, but not much larger)
*
               WRKBL = 3*M + LWORK_DGEBRD_MN
               IF( WNTQN ) THEN
*                 Path 5tn (N > M, jobz='N')
                  MAXWRK = MAX( WRKBL, 3*M + BDSPAC )
                  MINWRK = 3*M + MAX( N, BDSPAC )
               ELSE IF( WNTQO ) THEN
*                 Path 5to (N > M, jobz='O')
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DORMBR_QLN_MM )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DORMBR_PRT_MN )
                  WRKBL = MAX( WRKBL, 3*M + BDSPAC )
                  MAXWRK = WRKBL + M*N
                  MINWRK = 3*M + MAX( N, M*M + BDSPAC )
               ELSE IF( WNTQS ) THEN
*                 Path 5ts (N > M, jobz='S')
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DORMBR_QLN_MM )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DORMBR_PRT_MN )
                  MAXWRK = MAX( WRKBL, 3*M + BDSPAC )
                  MINWRK = 3*M + MAX( N, BDSPAC )
               ELSE IF( WNTQA ) THEN
*                 Path 5ta (N > M, jobz='A')
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DORMBR_QLN_MM )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DORMBR_PRT_NN )
                  MAXWRK = MAX( WRKBL, 3*M + BDSPAC )
                  MINWRK = 3*M + MAX( N, BDSPAC )
               END IF
            END IF
         END IF

         MAXWRK = MAX( MAXWRK, MINWRK )
         WORK( 1 ) = MAXWRK
*
         IF( LWORK.LT.MINWRK .AND. .NOT.LQUERY ) THEN
            INFO = -12
         END IF
      END IF
*
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGESDD', -INFO )
         RETURN
      ELSE IF( LQUERY ) THEN
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( M.EQ.0 .OR. N.EQ.0 ) THEN
         RETURN
      END IF
*
*     Get machine constants
*
      EPS = DLAMCH( 'P' )
      SMLNUM = SQRT( DLAMCH( 'S' ) ) / EPS
      BIGNUM = ONE / SMLNUM
*
*     Scale A if max element outside range [SMLNUM,BIGNUM]
*
      ANRM = DLANGE( 'M', M, N, A, LDA, DUM )
      ISCL = 0
      IF( ANRM.GT.ZERO .AND. ANRM.LT.SMLNUM ) THEN
         ISCL = 1
         CALL DLASCL( 'G', 0, 0, ANRM, SMLNUM, M, N, A, LDA, IERR )
      ELSE IF( ANRM.GT.BIGNUM ) THEN
         ISCL = 1
         CALL DLASCL( 'G', 0, 0, ANRM, BIGNUM, M, N, A, LDA, IERR )
      END IF
*
      IF( M.GE.N ) THEN
*
*        A has at least as many rows as columns. If A has sufficiently
*        more rows than columns, first reduce using the QR
*        decomposition (if sufficient workspace available)
*
         IF( M.GE.MNTHR ) THEN
*
            IF( WNTQN ) THEN
*
*              Path 1 (M >> N, JOBZ='N')
*              No singular vectors to be computed
*
               ITAU = 1
               NWORK = ITAU + N
*
*              Compute A=Q*R
*              Workspace: need   N [tau] + N    [work]
*              Workspace: prefer N [tau] + N*NB [work]
*
               CALL DGEQRF( M, N, A, LDA, WORK( ITAU ), WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
*
*              Zero out below R
*
               CALL DLASET( 'L', N-1, N-1, ZERO, ZERO, A( 2, 1 ), LDA )
               IE = 1
               ITAUQ = IE + N
               ITAUP = ITAUQ + N
               NWORK = ITAUP + N
*
*              Bidiagonalize R in A
*              Workspace: need   3*N [e, tauq, taup] + N      [work]
*              Workspace: prefer 3*N [e, tauq, taup] + 2*N*NB [work]
*
               CALL DGEBRD( N, N, A, LDA, S, WORK( IE ), WORK( ITAUQ ),
     $                      WORK( ITAUP ), WORK( NWORK ), LWORK-NWORK+1,
     $                      IERR )
               NWORK = IE + N
*
*              Perform bidiagonal SVD, computing singular values only
*              Workspace: need   N [e] + BDSPAC
*
               CALL DBDSDC( 'U', 'N', N, S, WORK( IE ), DUM, 1, DUM, 1,
     $                      DUM, IDUM, WORK( NWORK ), IWORK, INFO )
*
            ELSE IF( WNTQO ) THEN
*
*              Path 2 (M >> N, JOBZ = 'O')
*              N left singular vectors to be overwritten on A and
*              N right singular vectors to be computed in VT
*
               IR = 1
*
*              WORK(IR) is LDWRKR by N
*
               IF( LWORK .GE. LDA*N + N*N + 3*N + BDSPAC ) THEN
                  LDWRKR = LDA
               ELSE
                  LDWRKR = ( LWORK - N*N - 3*N - BDSPAC ) / N
               END IF
               ITAU = IR + LDWRKR*N
               NWORK = ITAU + N
*
*              Compute A=Q*R
*              Workspace: need   N*N [R] + N [tau] + N    [work]
*              Workspace: prefer N*N [R] + N [tau] + N*NB [work]
*
               CALL DGEQRF( M, N, A, LDA, WORK( ITAU ), WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
*
*              Copy R to WORK(IR), zeroing out below it
*
               CALL DLACPY( 'U', N, N, A, LDA, WORK( IR ), LDWRKR )
               CALL DLASET( 'L', N - 1, N - 1, ZERO, ZERO, WORK(IR+1),
     $                      LDWRKR )
*
*              Generate Q in A
*              Workspace: need   N*N [R] + N [tau] + N    [work]
*              Workspace: prefer N*N [R] + N [tau] + N*NB [work]
*
               CALL DORGQR( M, N, N, A, LDA, WORK( ITAU ),
     $                      WORK( NWORK ), LWORK - NWORK + 1, IERR )
               IE = ITAU
               ITAUQ = IE + N
               ITAUP = ITAUQ + N
               NWORK = ITAUP + N
*
*              Bidiagonalize R in WORK(IR)
*              Workspace: need   N*N [R] + 3*N [e, tauq, taup] + N      [work]
*              Workspace: prefer N*N [R] + 3*N [e, tauq, taup] + 2*N*NB [work]
*
               CALL DGEBRD( N, N, WORK( IR ), LDWRKR, S, WORK( IE ),
     $                      WORK( ITAUQ ), WORK( ITAUP ), WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
*
*              WORK(IU) is N by N
*
               IU = NWORK
               NWORK = IU + N*N
*
*              Perform bidiagonal SVD, computing left singular vectors
*              of bidiagonal matrix in WORK(IU) and computing right
*              singular vectors of bidiagonal matrix in VT
*              Workspace: need   N*N [R] + 3*N [e, tauq, taup] + N*N [U] + BDSPAC
*
               CALL DBDSDC( 'U', 'I', N, S, WORK( IE ), WORK( IU ), N,
     $                      VT, LDVT, DUM, IDUM, WORK( NWORK ), IWORK,
     $                      INFO )
*
*              Overwrite WORK(IU) by left singular vectors of R
*              and VT by right singular vectors of R
*              Workspace: need   N*N [R] + 3*N [e, tauq, taup] + N*N [U] + N    [work]
*              Workspace: prefer N*N [R] + 3*N [e, tauq, taup] + N*N [U] + N*NB [work]
*
               CALL DORMBR( 'Q', 'L', 'N', N, N, N, WORK( IR ), LDWRKR,
     $                      WORK( ITAUQ ), WORK( IU ), N, WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
               CALL DORMBR( 'P', 'R', 'T', N, N, N, WORK( IR ), LDWRKR,
     $                      WORK( ITAUP ), VT, LDVT, WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
*
*              Multiply Q in A by left singular vectors of R in
*              WORK(IU), storing result in WORK(IR) and copying to A
*              Workspace: need   N*N [R] + 3*N [e, tauq, taup] + N*N [U]
*              Workspace: prefer M*N [R] + 3*N [e, tauq, taup] + N*N [U]
*
               DO 10 I = 1, M, LDWRKR
                  CHUNK = MIN( M - I + 1, LDWRKR )
                  CALL DGEMM( 'N', 'N', CHUNK, N, N, ONE, A( I, 1 ),
     $                        LDA, WORK( IU ), N, ZERO, WORK( IR ),
     $                        LDWRKR )
                  CALL DLACPY( 'F', CHUNK, N, WORK( IR ), LDWRKR,
     $                         A( I, 1 ), LDA )
   10          CONTINUE
*
            ELSE IF( WNTQS ) THEN
*
*              Path 3 (M >> N, JOBZ='S')
*              N left singular vectors to be computed in U and
*              N right singular vectors to be computed in VT
*
               IR = 1
*
*              WORK(IR) is N by N
*
               LDWRKR = N
               ITAU = IR + LDWRKR*N
               NWORK = ITAU + N
*
*              Compute A=Q*R
*              Workspace: need   N*N [R] + N [tau] + N    [work]
*              Workspace: prefer N*N [R] + N [tau] + N*NB [work]
*
               CALL DGEQRF( M, N, A, LDA, WORK( ITAU ), WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
*
*              Copy R to WORK(IR), zeroing out below it
*
               CALL DLACPY( 'U', N, N, A, LDA, WORK( IR ), LDWRKR )
               CALL DLASET( 'L', N - 1, N - 1, ZERO, ZERO, WORK(IR+1),
     $                      LDWRKR )
*
*              Generate Q in A
*              Workspace: need   N*N [R] + N [tau] + N    [work]
*              Workspace: prefer N*N [R] + N [tau] + N*NB [work]
*
               CALL DORGQR( M, N, N, A, LDA, WORK( ITAU ),
     $                      WORK( NWORK ), LWORK - NWORK + 1, IERR )
               IE = ITAU
               ITAUQ = IE + N
               ITAUP = ITAUQ + N
               NWORK = ITAUP + N
*
*              Bidiagonalize R in WORK(IR)
*              Workspace: need   N*N [R] + 3*N [e, tauq, taup] + N      [work]
*              Workspace: prefer N*N [R] + 3*N [e, tauq, taup] + 2*N*NB [work]
*
               CALL DGEBRD( N, N, WORK( IR ), LDWRKR, S, WORK( IE ),
     $                      WORK( ITAUQ ), WORK( ITAUP ), WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
*
*              Perform bidiagonal SVD, computing left singular vectors
*              of bidiagoal matrix in U and computing right singular
*              vectors of bidiagonal matrix in VT
*              Workspace: need   N*N [R] + 3*N [e, tauq, taup] + BDSPAC
*
               CALL DBDSDC( 'U', 'I', N, S, WORK( IE ), U, LDU, VT,
     $                      LDVT, DUM, IDUM, WORK( NWORK ), IWORK,
     $                      INFO )
*
*              Overwrite U by left singular vectors of R and VT
*              by right singular vectors of R
*              Workspace: need   N*N [R] + 3*N [e, tauq, taup] + N    [work]
*              Workspace: prefer N*N [R] + 3*N [e, tauq, taup] + N*NB [work]
*
               CALL DORMBR( 'Q', 'L', 'N', N, N, N, WORK( IR ), LDWRKR,
     $                      WORK( ITAUQ ), U, LDU, WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
*
               CALL DORMBR( 'P', 'R', 'T', N, N, N, WORK( IR ), LDWRKR,
     $                      WORK( ITAUP ), VT, LDVT, WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
*
*              Multiply Q in A by left singular vectors of R in
*              WORK(IR), storing result in U
*              Workspace: need   N*N [R]
*
               CALL DLACPY( 'F', N, N, U, LDU, WORK( IR ), LDWRKR )
               CALL DGEMM( 'N', 'N', M, N, N, ONE, A, LDA, WORK( IR ),
     $                     LDWRKR, ZERO, U, LDU )
*
            ELSE IF( WNTQA ) THEN
*
*              Path 4 (M >> N, JOBZ='A')
*              M left singular vectors to be computed in U and
*              N right singular vectors to be computed in VT
*
               IU = 1
*
*              WORK(IU) is N by N
*
               LDWRKU = N
               ITAU = IU + LDWRKU*N
               NWORK = ITAU + N
*
*              Compute A=Q*R, copying result to U
*              Workspace: need   N*N [U] + N [tau] + N    [work]
*              Workspace: prefer N*N [U] + N [tau] + N*NB [work]
*
               CALL DGEQRF( M, N, A, LDA, WORK( ITAU ), WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
               CALL DLACPY( 'L', M, N, A, LDA, U, LDU )
*
*              Generate Q in U
*              Workspace: need   N*N [U] + N [tau] + M    [work]
*              Workspace: prefer N*N [U] + N [tau] + M*NB [work]
               CALL DORGQR( M, M, N, U, LDU, WORK( ITAU ),
     $                      WORK( NWORK ), LWORK - NWORK + 1, IERR )
*
*              Produce R in A, zeroing out other entries
*
               CALL DLASET( 'L', N-1, N-1, ZERO, ZERO, A( 2, 1 ), LDA )
               IE = ITAU
               ITAUQ = IE + N
               ITAUP = ITAUQ + N
               NWORK = ITAUP + N
*
*              Bidiagonalize R in A
*              Workspace: need   N*N [U] + 3*N [e, tauq, taup] + N      [work]
*              Workspace: prefer N*N [U] + 3*N [e, tauq, taup] + 2*N*NB [work]
*
               CALL DGEBRD( N, N, A, LDA, S, WORK( IE ), WORK( ITAUQ ),
     $                      WORK( ITAUP ), WORK( NWORK ), LWORK-NWORK+1,
     $                      IERR )
*
*              Perform bidiagonal SVD, computing left singular vectors
*              of bidiagonal matrix in WORK(IU) and computing right
*              singular vectors of bidiagonal matrix in VT
*              Workspace: need   N*N [U] + 3*N [e, tauq, taup] + BDSPAC
*
               CALL DBDSDC( 'U', 'I', N, S, WORK( IE ), WORK( IU ), N,
     $                      VT, LDVT, DUM, IDUM, WORK( NWORK ), IWORK,
     $                      INFO )
*
*              Overwrite WORK(IU) by left singular vectors of R and VT
*              by right singular vectors of R
*              Workspace: need   N*N [U] + 3*N [e, tauq, taup] + N    [work]
*              Workspace: prefer N*N [U] + 3*N [e, tauq, taup] + N*NB [work]
*
               CALL DORMBR( 'Q', 'L', 'N', N, N, N, A, LDA,
     $                      WORK( ITAUQ ), WORK( IU ), LDWRKU,
     $                      WORK( NWORK ), LWORK - NWORK + 1, IERR )
               CALL DORMBR( 'P', 'R', 'T', N, N, N, A, LDA,
     $                      WORK( ITAUP ), VT, LDVT, WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
*
*              Multiply Q in U by left singular vectors of R in
*              WORK(IU), storing result in A
*              Workspace: need   N*N [U]
*
               CALL DGEMM( 'N', 'N', M, N, N, ONE, U, LDU, WORK( IU ),
     $                     LDWRKU, ZERO, A, LDA )
*
*              Copy left singular vectors of A from A to U
*
               CALL DLACPY( 'F', M, N, A, LDA, U, LDU )
*
            END IF
*
         ELSE
*
*           M .LT. MNTHR
*
*           Path 5 (M >= N, but not much larger)
*           Reduce to bidiagonal form without QR decomposition
*
            IE = 1
            ITAUQ = IE + N
            ITAUP = ITAUQ + N
            NWORK = ITAUP + N
*
*           Bidiagonalize A
*           Workspace: need   3*N [e, tauq, taup] + M        [work]
*           Workspace: prefer 3*N [e, tauq, taup] + (M+N)*NB [work]
*
            CALL DGEBRD( M, N, A, LDA, S, WORK( IE ), WORK( ITAUQ ),
     $                   WORK( ITAUP ), WORK( NWORK ), LWORK-NWORK+1,
     $                   IERR )
            IF( WNTQN ) THEN
*
*              Path 5n (M >= N, JOBZ='N')
*              Perform bidiagonal SVD, only computing singular values
*              Workspace: need   3*N [e, tauq, taup] + BDSPAC
*
               CALL DBDSDC( 'U', 'N', N, S, WORK( IE ), DUM, 1, DUM, 1,
     $                      DUM, IDUM, WORK( NWORK ), IWORK, INFO )
            ELSE IF( WNTQO ) THEN
*              Path 5o (M >= N, JOBZ='O')
               IU = NWORK
               IF( LWORK .GE. M*N + 3*N + BDSPAC ) THEN
*
*                 WORK( IU ) is M by N
*
                  LDWRKU = M
                  NWORK = IU + LDWRKU*N
                  CALL DLASET( 'F', M, N, ZERO, ZERO, WORK( IU ),
     $                         LDWRKU )
*                 IR is unused; silence compile warnings
                  IR = -1
               ELSE
*
*                 WORK( IU ) is N by N
*
                  LDWRKU = N
                  NWORK = IU + LDWRKU*N
*
*                 WORK(IR) is LDWRKR by N
*
                  IR = NWORK
                  LDWRKR = ( LWORK - N*N - 3*N ) / N
               END IF
               NWORK = IU + LDWRKU*N
*
*              Perform bidiagonal SVD, computing left singular vectors
*              of bidiagonal matrix in WORK(IU) and computing right
*              singular vectors of bidiagonal matrix in VT
*              Workspace: need   3*N [e, tauq, taup] + N*N [U] + BDSPAC
*
               CALL DBDSDC( 'U', 'I', N, S, WORK( IE ), WORK( IU ),
     $                      LDWRKU, VT, LDVT, DUM, IDUM, WORK( NWORK ),
     $                      IWORK, INFO )
*
*              Overwrite VT by right singular vectors of A
*              Workspace: need   3*N [e, tauq, taup] + N*N [U] + N    [work]
*              Workspace: prefer 3*N [e, tauq, taup] + N*N [U] + N*NB [work]
*
               CALL DORMBR( 'P', 'R', 'T', N, N, N, A, LDA,
     $                      WORK( ITAUP ), VT, LDVT, WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
*
               IF( LWORK .GE. M*N + 3*N + BDSPAC ) THEN
*
*                 Path 5o-fast
*                 Overwrite WORK(IU) by left singular vectors of A
*                 Workspace: need   3*N [e, tauq, taup] + M*N [U] + N    [work]
*                 Workspace: prefer 3*N [e, tauq, taup] + M*N [U] + N*NB [work]
*
                  CALL DORMBR( 'Q', 'L', 'N', M, N, N, A, LDA,
     $                         WORK( ITAUQ ), WORK( IU ), LDWRKU,
     $                         WORK( NWORK ), LWORK - NWORK + 1, IERR )
*
*                 Copy left singular vectors of A from WORK(IU) to A
*
                  CALL DLACPY( 'F', M, N, WORK( IU ), LDWRKU, A, LDA )
               ELSE
*
*                 Path 5o-slow
*                 Generate Q in A
*                 Workspace: need   3*N [e, tauq, taup] + N*N [U] + N    [work]
*                 Workspace: prefer 3*N [e, tauq, taup] + N*N [U] + N*NB [work]
*
                  CALL DORGBR( 'Q', M, N, N, A, LDA, WORK( ITAUQ ),
     $                         WORK( NWORK ), LWORK - NWORK + 1, IERR )
*
*                 Multiply Q in A by left singular vectors of
*                 bidiagonal matrix in WORK(IU), storing result in
*                 WORK(IR) and copying to A
*                 Workspace: need   3*N [e, tauq, taup] + N*N [U] + NB*N [R]
*                 Workspace: prefer 3*N [e, tauq, taup] + N*N [U] + M*N  [R]
*
                  DO 20 I = 1, M, LDWRKR
                     CHUNK = MIN( M - I + 1, LDWRKR )
                     CALL DGEMM( 'N', 'N', CHUNK, N, N, ONE, A( I, 1 ),
     $                           LDA, WORK( IU ), LDWRKU, ZERO,
     $                           WORK( IR ), LDWRKR )
                     CALL DLACPY( 'F', CHUNK, N, WORK( IR ), LDWRKR,
     $                            A( I, 1 ), LDA )
   20             CONTINUE
               END IF
*
            ELSE IF( WNTQS ) THEN
*
*              Path 5s (M >= N, JOBZ='S')
*              Perform bidiagonal SVD, computing left singular vectors
*              of bidiagonal matrix in U and computing right singular
*              vectors of bidiagonal matrix in VT
*              Workspace: need   3*N [e, tauq, taup] + BDSPAC
*
               CALL DLASET( 'F', M, N, ZERO, ZERO, U, LDU )
               CALL DBDSDC( 'U', 'I', N, S, WORK( IE ), U, LDU, VT,
     $                      LDVT, DUM, IDUM, WORK( NWORK ), IWORK,
     $                      INFO )
*
*              Overwrite U by left singular vectors of A and VT
*              by right singular vectors of A
*              Workspace: need   3*N [e, tauq, taup] + N    [work]
*              Workspace: prefer 3*N [e, tauq, taup] + N*NB [work]
*
               CALL DORMBR( 'Q', 'L', 'N', M, N, N, A, LDA,
     $                      WORK( ITAUQ ), U, LDU, WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
               CALL DORMBR( 'P', 'R', 'T', N, N, N, A, LDA,
     $                      WORK( ITAUP ), VT, LDVT, WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
            ELSE IF( WNTQA ) THEN
*
*              Path 5a (M >= N, JOBZ='A')
*              Perform bidiagonal SVD, computing left singular vectors
*              of bidiagonal matrix in U and computing right singular
*              vectors of bidiagonal matrix in VT
*              Workspace: need   3*N [e, tauq, taup] + BDSPAC
*
               CALL DLASET( 'F', M, M, ZERO, ZERO, U, LDU )
               CALL DBDSDC( 'U', 'I', N, S, WORK( IE ), U, LDU, VT,
     $                      LDVT, DUM, IDUM, WORK( NWORK ), IWORK,
     $                      INFO )
*
*              Set the right corner of U to identity matrix
*
               IF( M.GT.N ) THEN
                  CALL DLASET( 'F', M - N, M - N, ZERO, ONE, U(N+1,N+1),
     $                         LDU )
               END IF
*
*              Overwrite U by left singular vectors of A and VT
*              by right singular vectors of A
*              Workspace: need   3*N [e, tauq, taup] + M    [work]
*              Workspace: prefer 3*N [e, tauq, taup] + M*NB [work]
*
               CALL DORMBR( 'Q', 'L', 'N', M, M, N, A, LDA,
     $                      WORK( ITAUQ ), U, LDU, WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
               CALL DORMBR( 'P', 'R', 'T', N, N, M, A, LDA,
     $                      WORK( ITAUP ), VT, LDVT, WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
            END IF
*
         END IF
*
      ELSE
*
*        A has more columns than rows. If A has sufficiently more
*        columns than rows, first reduce using the LQ decomposition (if
*        sufficient workspace available)
*
         IF( N.GE.MNTHR ) THEN
*
            IF( WNTQN ) THEN
*
*              Path 1t (N >> M, JOBZ='N')
*              No singular vectors to be computed
*
               ITAU = 1
               NWORK = ITAU + M
*
*              Compute A=L*Q
*              Workspace: need   M [tau] + M [work]
*              Workspace: prefer M [tau] + M*NB [work]
*
               CALL DGELQF( M, N, A, LDA, WORK( ITAU ), WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
*
*              Zero out above L
*
               CALL DLASET( 'U', M-1, M-1, ZERO, ZERO, A( 1, 2 ), LDA )
               IE = 1
               ITAUQ = IE + M
               ITAUP = ITAUQ + M
               NWORK = ITAUP + M
*
*              Bidiagonalize L in A
*              Workspace: need   3*M [e, tauq, taup] + M      [work]
*              Workspace: prefer 3*M [e, tauq, taup] + 2*M*NB [work]
*
               CALL DGEBRD( M, M, A, LDA, S, WORK( IE ), WORK( ITAUQ ),
     $                      WORK( ITAUP ), WORK( NWORK ), LWORK-NWORK+1,
     $                      IERR )
               NWORK = IE + M
*
*              Perform bidiagonal SVD, computing singular values only
*              Workspace: need   M [e] + BDSPAC
*
               CALL DBDSDC( 'U', 'N', M, S, WORK( IE ), DUM, 1, DUM, 1,
     $                      DUM, IDUM, WORK( NWORK ), IWORK, INFO )
*
            ELSE IF( WNTQO ) THEN
*
*              Path 2t (N >> M, JOBZ='O')
*              M right singular vectors to be overwritten on A and
*              M left singular vectors to be computed in U
*
               IVT = 1
*
*              WORK(IVT) is M by M
*              WORK(IL)  is M by M; it is later resized to M by chunk for gemm
*
               IL = IVT + M*M
               IF( LWORK .GE. M*N + M*M + 3*M + BDSPAC ) THEN
                  LDWRKL = M
                  CHUNK = N
               ELSE
                  LDWRKL = M
                  CHUNK = ( LWORK - M*M ) / M
               END IF
               ITAU = IL + LDWRKL*M
               NWORK = ITAU + M
*
*              Compute A=L*Q
*              Workspace: need   M*M [VT] + M*M [L] + M [tau] + M    [work]
*              Workspace: prefer M*M [VT] + M*M [L] + M [tau] + M*NB [work]
*
               CALL DGELQF( M, N, A, LDA, WORK( ITAU ), WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
*
*              Copy L to WORK(IL), zeroing about above it
*
               CALL DLACPY( 'L', M, M, A, LDA, WORK( IL ), LDWRKL )
               CALL DLASET( 'U', M - 1, M - 1, ZERO, ZERO,
     $                      WORK( IL + LDWRKL ), LDWRKL )
*
*              Generate Q in A
*              Workspace: need   M*M [VT] + M*M [L] + M [tau] + M    [work]
*              Workspace: prefer M*M [VT] + M*M [L] + M [tau] + M*NB [work]
*
               CALL DORGLQ( M, N, M, A, LDA, WORK( ITAU ),
     $                      WORK( NWORK ), LWORK - NWORK + 1, IERR )
               IE = ITAU
               ITAUQ = IE + M
               ITAUP = ITAUQ + M
               NWORK = ITAUP + M
*
*              Bidiagonalize L in WORK(IL)
*              Workspace: need   M*M [VT] + M*M [L] + 3*M [e, tauq, taup] + M      [work]
*              Workspace: prefer M*M [VT] + M*M [L] + 3*M [e, tauq, taup] + 2*M*NB [work]
*
               CALL DGEBRD( M, M, WORK( IL ), LDWRKL, S, WORK( IE ),
     $                      WORK( ITAUQ ), WORK( ITAUP ), WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
*
*              Perform bidiagonal SVD, computing left singular vectors
*              of bidiagonal matrix in U, and computing right singular
*              vectors of bidiagonal matrix in WORK(IVT)
*              Workspace: need   M*M [VT] + M*M [L] + 3*M [e, tauq, taup] + BDSPAC
*
               CALL DBDSDC( 'U', 'I', M, S, WORK( IE ), U, LDU,
     $                      WORK( IVT ), M, DUM, IDUM, WORK( NWORK ),
     $                      IWORK, INFO )
*
*              Overwrite U by left singular vectors of L and WORK(IVT)
*              by right singular vectors of L
*              Workspace: need   M*M [VT] + M*M [L] + 3*M [e, tauq, taup] + M    [work]
*              Workspace: prefer M*M [VT] + M*M [L] + 3*M [e, tauq, taup] + M*NB [work]
*
               CALL DORMBR( 'Q', 'L', 'N', M, M, M, WORK( IL ), LDWRKL,
     $                      WORK( ITAUQ ), U, LDU, WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
               CALL DORMBR( 'P', 'R', 'T', M, M, M, WORK( IL ), LDWRKL,
     $                      WORK( ITAUP ), WORK( IVT ), M,
     $                      WORK( NWORK ), LWORK - NWORK + 1, IERR )
*
*              Multiply right singular vectors of L in WORK(IVT) by Q
*              in A, storing result in WORK(IL) and copying to A
*              Workspace: need   M*M [VT] + M*M [L]
*              Workspace: prefer M*M [VT] + M*N [L]
*              At this point, L is resized as M by chunk.
*
               DO 30 I = 1, N, CHUNK
                  BLK = MIN( N - I + 1, CHUNK )
                  CALL DGEMM( 'N', 'N', M, BLK, M, ONE, WORK( IVT ), M,
     $                        A( 1, I ), LDA, ZERO, WORK( IL ), LDWRKL )
                  CALL DLACPY( 'F', M, BLK, WORK( IL ), LDWRKL,
     $                         A( 1, I ), LDA )
   30          CONTINUE
*
            ELSE IF( WNTQS ) THEN
*
*              Path 3t (N >> M, JOBZ='S')
*              M right singular vectors to be computed in VT and
*              M left singular vectors to be computed in U
*
               IL = 1
*
*              WORK(IL) is M by M
*
               LDWRKL = M
               ITAU = IL + LDWRKL*M
               NWORK = ITAU + M
*
*              Compute A=L*Q
*              Workspace: need   M*M [L] + M [tau] + M    [work]
*              Workspace: prefer M*M [L] + M [tau] + M*NB [work]
*
               CALL DGELQF( M, N, A, LDA, WORK( ITAU ), WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
*
*              Copy L to WORK(IL), zeroing out above it
*
               CALL DLACPY( 'L', M, M, A, LDA, WORK( IL ), LDWRKL )
               CALL DLASET( 'U', M - 1, M - 1, ZERO, ZERO,
     $                      WORK( IL + LDWRKL ), LDWRKL )
*
*              Generate Q in A
*              Workspace: need   M*M [L] + M [tau] + M    [work]
*              Workspace: prefer M*M [L] + M [tau] + M*NB [work]
*
               CALL DORGLQ( M, N, M, A, LDA, WORK( ITAU ),
     $                      WORK( NWORK ), LWORK - NWORK + 1, IERR )
               IE = ITAU
               ITAUQ = IE + M
               ITAUP = ITAUQ + M
               NWORK = ITAUP + M
*
*              Bidiagonalize L in WORK(IU).
*              Workspace: need   M*M [L] + 3*M [e, tauq, taup] + M      [work]
*              Workspace: prefer M*M [L] + 3*M [e, tauq, taup] + 2*M*NB [work]
*
               CALL DGEBRD( M, M, WORK( IL ), LDWRKL, S, WORK( IE ),
     $                      WORK( ITAUQ ), WORK( ITAUP ), WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
*
*              Perform bidiagonal SVD, computing left singular vectors
*              of bidiagonal matrix in U and computing right singular
*              vectors of bidiagonal matrix in VT
*              Workspace: need   M*M [L] + 3*M [e, tauq, taup] + BDSPAC
*
               CALL DBDSDC( 'U', 'I', M, S, WORK( IE ), U, LDU, VT,
     $                      LDVT, DUM, IDUM, WORK( NWORK ), IWORK,
     $                      INFO )
*
*              Overwrite U by left singular vectors of L and VT
*              by right singular vectors of L
*              Workspace: need   M*M [L] + 3*M [e, tauq, taup] + M    [work]
*              Workspace: prefer M*M [L] + 3*M [e, tauq, taup] + M*NB [work]
*
               CALL DORMBR( 'Q', 'L', 'N', M, M, M, WORK( IL ), LDWRKL,
     $                      WORK( ITAUQ ), U, LDU, WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
               CALL DORMBR( 'P', 'R', 'T', M, M, M, WORK( IL ), LDWRKL,
     $                      WORK( ITAUP ), VT, LDVT, WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
*
*              Multiply right singular vectors of L in WORK(IL) by
*              Q in A, storing result in VT
*              Workspace: need   M*M [L]
*
               CALL DLACPY( 'F', M, M, VT, LDVT, WORK( IL ), LDWRKL )
               CALL DGEMM( 'N', 'N', M, N, M, ONE, WORK( IL ), LDWRKL,
     $                     A, LDA, ZERO, VT, LDVT )
*
            ELSE IF( WNTQA ) THEN
*
*              Path 4t (N >> M, JOBZ='A')
*              N right singular vectors to be computed in VT and
*              M left singular vectors to be computed in U
*
               IVT = 1
*
*              WORK(IVT) is M by M
*
               LDWKVT = M
               ITAU = IVT + LDWKVT*M
               NWORK = ITAU + M
*
*              Compute A=L*Q, copying result to VT
*              Workspace: need   M*M [VT] + M [tau] + M    [work]
*              Workspace: prefer M*M [VT] + M [tau] + M*NB [work]
*
               CALL DGELQF( M, N, A, LDA, WORK( ITAU ), WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
               CALL DLACPY( 'U', M, N, A, LDA, VT, LDVT )
*
*              Generate Q in VT
*              Workspace: need   M*M [VT] + M [tau] + N    [work]
*              Workspace: prefer M*M [VT] + M [tau] + N*NB [work]
*
               CALL DORGLQ( N, N, M, VT, LDVT, WORK( ITAU ),
     $                      WORK( NWORK ), LWORK - NWORK + 1, IERR )
*
*              Produce L in A, zeroing out other entries
*
               CALL DLASET( 'U', M-1, M-1, ZERO, ZERO, A( 1, 2 ), LDA )
               IE = ITAU
               ITAUQ = IE + M
               ITAUP = ITAUQ + M
               NWORK = ITAUP + M
*
*              Bidiagonalize L in A
*              Workspace: need   M*M [VT] + 3*M [e, tauq, taup] + M      [work]
*              Workspace: prefer M*M [VT] + 3*M [e, tauq, taup] + 2*M*NB [work]
*
               CALL DGEBRD( M, M, A, LDA, S, WORK( IE ), WORK( ITAUQ ),
     $                      WORK( ITAUP ), WORK( NWORK ), LWORK-NWORK+1,
     $                      IERR )
*
*              Perform bidiagonal SVD, computing left singular vectors
*              of bidiagonal matrix in U and computing right singular
*              vectors of bidiagonal matrix in WORK(IVT)
*              Workspace: need   M*M [VT] + 3*M [e, tauq, taup] + BDSPAC
*
               CALL DBDSDC( 'U', 'I', M, S, WORK( IE ), U, LDU,
     $                      WORK( IVT ), LDWKVT, DUM, IDUM,
     $                      WORK( NWORK ), IWORK, INFO )
*
*              Overwrite U by left singular vectors of L and WORK(IVT)
*              by right singular vectors of L
*              Workspace: need   M*M [VT] + 3*M [e, tauq, taup]+ M    [work]
*              Workspace: prefer M*M [VT] + 3*M [e, tauq, taup]+ M*NB [work]
*
               CALL DORMBR( 'Q', 'L', 'N', M, M, M, A, LDA,
     $                      WORK( ITAUQ ), U, LDU, WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
               CALL DORMBR( 'P', 'R', 'T', M, M, M, A, LDA,
     $                      WORK( ITAUP ), WORK( IVT ), LDWKVT,
     $                      WORK( NWORK ), LWORK - NWORK + 1, IERR )
*
*              Multiply right singular vectors of L in WORK(IVT) by
*              Q in VT, storing result in A
*              Workspace: need   M*M [VT]
*
               CALL DGEMM( 'N', 'N', M, N, M, ONE, WORK( IVT ), LDWKVT,
     $                     VT, LDVT, ZERO, A, LDA )
*
*              Copy right singular vectors of A from A to VT
*
               CALL DLACPY( 'F', M, N, A, LDA, VT, LDVT )
*
            END IF
*
         ELSE
*
*           N .LT. MNTHR
*
*           Path 5t (N > M, but not much larger)
*           Reduce to bidiagonal form without LQ decomposition
*
            IE = 1
            ITAUQ = IE + M
            ITAUP = ITAUQ + M
            NWORK = ITAUP + M
*
*           Bidiagonalize A
*           Workspace: need   3*M [e, tauq, taup] + N        [work]
*           Workspace: prefer 3*M [e, tauq, taup] + (M+N)*NB [work]
*
            CALL DGEBRD( M, N, A, LDA, S, WORK( IE ), WORK( ITAUQ ),
     $                   WORK( ITAUP ), WORK( NWORK ), LWORK-NWORK+1,
     $                   IERR )
            IF( WNTQN ) THEN
*
*              Path 5tn (N > M, JOBZ='N')
*              Perform bidiagonal SVD, only computing singular values
*              Workspace: need   3*M [e, tauq, taup] + BDSPAC
*
               CALL DBDSDC( 'L', 'N', M, S, WORK( IE ), DUM, 1, DUM, 1,
     $                      DUM, IDUM, WORK( NWORK ), IWORK, INFO )
            ELSE IF( WNTQO ) THEN
*              Path 5to (N > M, JOBZ='O')
               LDWKVT = M
               IVT = NWORK
               IF( LWORK .GE. M*N + 3*M + BDSPAC ) THEN
*
*                 WORK( IVT ) is M by N
*
                  CALL DLASET( 'F', M, N, ZERO, ZERO, WORK( IVT ),
     $                         LDWKVT )
                  NWORK = IVT + LDWKVT*N
*                 IL is unused; silence compile warnings
                  IL = -1
               ELSE
*
*                 WORK( IVT ) is M by M
*
                  NWORK = IVT + LDWKVT*M
                  IL = NWORK
*
*                 WORK(IL) is M by CHUNK
*
                  CHUNK = ( LWORK - M*M - 3*M ) / M
               END IF
*
*              Perform bidiagonal SVD, computing left singular vectors
*              of bidiagonal matrix in U and computing right singular
*              vectors of bidiagonal matrix in WORK(IVT)
*              Workspace: need   3*M [e, tauq, taup] + M*M [VT] + BDSPAC
*
               CALL DBDSDC( 'L', 'I', M, S, WORK( IE ), U, LDU,
     $                      WORK( IVT ), LDWKVT, DUM, IDUM,
     $                      WORK( NWORK ), IWORK, INFO )
*
*              Overwrite U by left singular vectors of A
*              Workspace: need   3*M [e, tauq, taup] + M*M [VT] + M    [work]
*              Workspace: prefer 3*M [e, tauq, taup] + M*M [VT] + M*NB [work]
*
               CALL DORMBR( 'Q', 'L', 'N', M, M, N, A, LDA,
     $                      WORK( ITAUQ ), U, LDU, WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
*
               IF( LWORK .GE. M*N + 3*M + BDSPAC ) THEN
*
*                 Path 5to-fast
*                 Overwrite WORK(IVT) by left singular vectors of A
*                 Workspace: need   3*M [e, tauq, taup] + M*N [VT] + M    [work]
*                 Workspace: prefer 3*M [e, tauq, taup] + M*N [VT] + M*NB [work]
*
                  CALL DORMBR( 'P', 'R', 'T', M, N, M, A, LDA,
     $                         WORK( ITAUP ), WORK( IVT ), LDWKVT,
     $                         WORK( NWORK ), LWORK - NWORK + 1, IERR )
*
*                 Copy right singular vectors of A from WORK(IVT) to A
*
                  CALL DLACPY( 'F', M, N, WORK( IVT ), LDWKVT, A, LDA )
               ELSE
*
*                 Path 5to-slow
*                 Generate P**T in A
*                 Workspace: need   3*M [e, tauq, taup] + M*M [VT] + M    [work]
*                 Workspace: prefer 3*M [e, tauq, taup] + M*M [VT] + M*NB [work]
*
                  CALL DORGBR( 'P', M, N, M, A, LDA, WORK( ITAUP ),
     $                         WORK( NWORK ), LWORK - NWORK + 1, IERR )
*
*                 Multiply Q in A by right singular vectors of
*                 bidiagonal matrix in WORK(IVT), storing result in
*                 WORK(IL) and copying to A
*                 Workspace: need   3*M [e, tauq, taup] + M*M [VT] + M*NB [L]
*                 Workspace: prefer 3*M [e, tauq, taup] + M*M [VT] + M*N  [L]
*
                  DO 40 I = 1, N, CHUNK
                     BLK = MIN( N - I + 1, CHUNK )
                     CALL DGEMM( 'N', 'N', M, BLK, M, ONE, WORK( IVT ),
     $                           LDWKVT, A( 1, I ), LDA, ZERO,
     $                           WORK( IL ), M )
                     CALL DLACPY( 'F', M, BLK, WORK( IL ), M, A( 1, I ),
     $                            LDA )
   40             CONTINUE
               END IF
            ELSE IF( WNTQS ) THEN
*
*              Path 5ts (N > M, JOBZ='S')
*              Perform bidiagonal SVD, computing left singular vectors
*              of bidiagonal matrix in U and computing right singular
*              vectors of bidiagonal matrix in VT
*              Workspace: need   3*M [e, tauq, taup] + BDSPAC
*
               CALL DLASET( 'F', M, N, ZERO, ZERO, VT, LDVT )
               CALL DBDSDC( 'L', 'I', M, S, WORK( IE ), U, LDU, VT,
     $                      LDVT, DUM, IDUM, WORK( NWORK ), IWORK,
     $                      INFO )
*
*              Overwrite U by left singular vectors of A and VT
*              by right singular vectors of A
*              Workspace: need   3*M [e, tauq, taup] + M    [work]
*              Workspace: prefer 3*M [e, tauq, taup] + M*NB [work]
*
               CALL DORMBR( 'Q', 'L', 'N', M, M, N, A, LDA,
     $                      WORK( ITAUQ ), U, LDU, WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
               CALL DORMBR( 'P', 'R', 'T', M, N, M, A, LDA,
     $                      WORK( ITAUP ), VT, LDVT, WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
            ELSE IF( WNTQA ) THEN
*
*              Path 5ta (N > M, JOBZ='A')
*              Perform bidiagonal SVD, computing left singular vectors
*              of bidiagonal matrix in U and computing right singular
*              vectors of bidiagonal matrix in VT
*              Workspace: need   3*M [e, tauq, taup] + BDSPAC
*
               CALL DLASET( 'F', N, N, ZERO, ZERO, VT, LDVT )
               CALL DBDSDC( 'L', 'I', M, S, WORK( IE ), U, LDU, VT,
     $                      LDVT, DUM, IDUM, WORK( NWORK ), IWORK,
     $                      INFO )
*
*              Set the right corner of VT to identity matrix
*
               IF( N.GT.M ) THEN
                  CALL DLASET( 'F', N-M, N-M, ZERO, ONE, VT(M+1,M+1),
     $                         LDVT )
               END IF
*
*              Overwrite U by left singular vectors of A and VT
*              by right singular vectors of A
*              Workspace: need   3*M [e, tauq, taup] + N    [work]
*              Workspace: prefer 3*M [e, tauq, taup] + N*NB [work]
*
               CALL DORMBR( 'Q', 'L', 'N', M, M, N, A, LDA,
     $                      WORK( ITAUQ ), U, LDU, WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
               CALL DORMBR( 'P', 'R', 'T', N, N, M, A, LDA,
     $                      WORK( ITAUP ), VT, LDVT, WORK( NWORK ),
     $                      LWORK - NWORK + 1, IERR )
            END IF
*
         END IF
*
      END IF
*
*     Undo scaling if necessary
*
      IF( ISCL.EQ.1 ) THEN
         IF( ANRM.GT.BIGNUM )
     $      CALL DLASCL( 'G', 0, 0, BIGNUM, ANRM, MINMN, 1, S, MINMN,
     $                   IERR )
         IF( ANRM.LT.SMLNUM )
     $      CALL DLASCL( 'G', 0, 0, SMLNUM, ANRM, MINMN, 1, S, MINMN,
     $                   IERR )
      END IF
*
*     Return optimal workspace in WORK(1)
*
      WORK( 1 ) = MAXWRK
*
      RETURN
*
*     End of DGESDD
*
      END
*> \brief <b> DGESV computes the solution to system of linear equations A * X = B for GE matrices</b>
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGESV + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgesv.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgesv.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgesv.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGESV( N, NRHS, A, LDA, IPIV, B, LDB, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, LDA, LDB, N, NRHS
*       ..
*       .. Array Arguments ..
*       INTEGER            IPIV( * )
*       DOUBLE PRECISION   A( LDA, * ), B( LDB, * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGESV computes the solution to a real system of linear equations
*>    A * X = B,
*> where A is an N-by-N matrix and X and B are N-by-NRHS matrices.
*>
*> The LU decomposition with partial pivoting and row interchanges is
*> used to factor A as
*>    A = P * L * U,
*> where P is a permutation matrix, L is unit lower triangular, and U is
*> upper triangular.  The factored form of A is then used to solve the
*> system of equations A * X = B.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of linear equations, i.e., the order of the
*>          matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in] NRHS
*> \verbatim
*>          NRHS is INTEGER
*>          The number of right hand sides, i.e., the number of columns
*>          of the matrix B.  NRHS >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the N-by-N coefficient matrix A.
*>          On exit, the factors L and U from the factorization
*>          A = P*L*U; the unit diagonal elements of L are not stored.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,N).
*> \endverbatim
*>
*> \param[out] IPIV
*> \verbatim
*>          IPIV is INTEGER array, dimension (N)
*>          The pivot indices that define the permutation matrix P;
*>          row i of the matrix was interchanged with row IPIV(i).
*> \endverbatim
*>
*> \param[in,out] B
*> \verbatim
*>          B is DOUBLE PRECISION array, dimension (LDB,NRHS)
*>          On entry, the N-by-NRHS matrix of right hand side matrix B.
*>          On exit, if INFO = 0, the N-by-NRHS solution matrix X.
*> \endverbatim
*>
*> \param[in] LDB
*> \verbatim
*>          LDB is INTEGER
*>          The leading dimension of the array B.  LDB >= max(1,N).
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value
*>          > 0:  if INFO = i, U(i,i) is exactly zero.  The factorization
*>                has been completed, but the factor U is exactly
*>                singular, so the solution could not be computed.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEsolve
*
*  =====================================================================
      SUBROUTINE DGESV( N, NRHS, A, LDA, IPIV, B, LDB, INFO )
*
*  -- LAPACK driver routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER            INFO, LDA, LDB, N, NRHS
*     ..
*     .. Array Arguments ..
      INTEGER            IPIV( * )
      DOUBLE PRECISION   A( LDA, * ), B( LDB, * )
*     ..
*
*  =====================================================================
*
*     .. External Subroutines ..
      EXTERNAL           DGETRF, DGETRS, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX
*     ..
*     .. Executable Statements ..
*
*     Test the input parameters.
*
      INFO = 0
      IF( N.LT.0 ) THEN
         INFO = -1
      ELSE IF( NRHS.LT.0 ) THEN
         INFO = -2
      ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
         INFO = -4
      ELSE IF( LDB.LT.MAX( 1, N ) ) THEN
         INFO = -7
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGESV ', -INFO )
         RETURN
      END IF
*
*     Compute the LU factorization of A.
*
      CALL DGETRF( N, N, A, LDA, IPIV, INFO )
      IF( INFO.EQ.0 ) THEN
*
*        Solve the system A*X = B, overwriting B with X.
*
         CALL DGETRS( 'No transpose', N, NRHS, A, LDA, IPIV, B, LDB,
     $                INFO )
      END IF
      RETURN
*
*     End of DGESV
*
      END
*> \brief <b> DGESVD computes the singular value decomposition (SVD) for GE matrices</b>
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGESVD + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgesvd.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgesvd.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgesvd.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGESVD( JOBU, JOBVT, M, N, A, LDA, S, U, LDU, VT, LDVT,
*                          WORK, LWORK, INFO )
*
*       .. Scalar Arguments ..
*       CHARACTER          JOBU, JOBVT
*       INTEGER            INFO, LDA, LDU, LDVT, LWORK, M, N
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   A( LDA, * ), S( * ), U( LDU, * ),
*      $                   VT( LDVT, * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGESVD computes the singular value decomposition (SVD) of a real
*> M-by-N matrix A, optionally computing the left and/or right singular
*> vectors. The SVD is written
*>
*>      A = U * SIGMA * transpose(V)
*>
*> where SIGMA is an M-by-N matrix which is zero except for its
*> min(m,n) diagonal elements, U is an M-by-M orthogonal matrix, and
*> V is an N-by-N orthogonal matrix.  The diagonal elements of SIGMA
*> are the singular values of A; they are real and non-negative, and
*> are returned in descending order.  The first min(m,n) columns of
*> U and V are the left and right singular vectors of A.
*>
*> Note that the routine returns V**T, not V.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] JOBU
*> \verbatim
*>          JOBU is CHARACTER*1
*>          Specifies options for computing all or part of the matrix U:
*>          = 'A':  all M columns of U are returned in array U:
*>          = 'S':  the first min(m,n) columns of U (the left singular
*>                  vectors) are returned in the array U;
*>          = 'O':  the first min(m,n) columns of U (the left singular
*>                  vectors) are overwritten on the array A;
*>          = 'N':  no columns of U (no left singular vectors) are
*>                  computed.
*> \endverbatim
*>
*> \param[in] JOBVT
*> \verbatim
*>          JOBVT is CHARACTER*1
*>          Specifies options for computing all or part of the matrix
*>          V**T:
*>          = 'A':  all N rows of V**T are returned in the array VT;
*>          = 'S':  the first min(m,n) rows of V**T (the right singular
*>                  vectors) are returned in the array VT;
*>          = 'O':  the first min(m,n) rows of V**T (the right singular
*>                  vectors) are overwritten on the array A;
*>          = 'N':  no rows of V**T (no right singular vectors) are
*>                  computed.
*>
*>          JOBVT and JOBU cannot both be 'O'.
*> \endverbatim
*>
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the input matrix A.  M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the input matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the M-by-N matrix A.
*>          On exit,
*>          if JOBU = 'O',  A is overwritten with the first min(m,n)
*>                          columns of U (the left singular vectors,
*>                          stored columnwise);
*>          if JOBVT = 'O', A is overwritten with the first min(m,n)
*>                          rows of V**T (the right singular vectors,
*>                          stored rowwise);
*>          if JOBU .ne. 'O' and JOBVT .ne. 'O', the contents of A
*>                          are destroyed.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,M).
*> \endverbatim
*>
*> \param[out] S
*> \verbatim
*>          S is DOUBLE PRECISION array, dimension (min(M,N))
*>          The singular values of A, sorted so that S(i) >= S(i+1).
*> \endverbatim
*>
*> \param[out] U
*> \verbatim
*>          U is DOUBLE PRECISION array, dimension (LDU,UCOL)
*>          (LDU,M) if JOBU = 'A' or (LDU,min(M,N)) if JOBU = 'S'.
*>          If JOBU = 'A', U contains the M-by-M orthogonal matrix U;
*>          if JOBU = 'S', U contains the first min(m,n) columns of U
*>          (the left singular vectors, stored columnwise);
*>          if JOBU = 'N' or 'O', U is not referenced.
*> \endverbatim
*>
*> \param[in] LDU
*> \verbatim
*>          LDU is INTEGER
*>          The leading dimension of the array U.  LDU >= 1; if
*>          JOBU = 'S' or 'A', LDU >= M.
*> \endverbatim
*>
*> \param[out] VT
*> \verbatim
*>          VT is DOUBLE PRECISION array, dimension (LDVT,N)
*>          If JOBVT = 'A', VT contains the N-by-N orthogonal matrix
*>          V**T;
*>          if JOBVT = 'S', VT contains the first min(m,n) rows of
*>          V**T (the right singular vectors, stored rowwise);
*>          if JOBVT = 'N' or 'O', VT is not referenced.
*> \endverbatim
*>
*> \param[in] LDVT
*> \verbatim
*>          LDVT is INTEGER
*>          The leading dimension of the array VT.  LDVT >= 1; if
*>          JOBVT = 'A', LDVT >= N; if JOBVT = 'S', LDVT >= min(M,N).
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK))
*>          On exit, if INFO = 0, WORK(1) returns the optimal LWORK;
*>          if INFO > 0, WORK(2:MIN(M,N)) contains the unconverged
*>          superdiagonal elements of an upper bidiagonal matrix B
*>          whose diagonal is in S (not necessarily sorted). B
*>          satisfies A = U * B * VT, so it has the same singular values
*>          as A, and singular vectors related by U and VT.
*> \endverbatim
*>
*> \param[in] LWORK
*> \verbatim
*>          LWORK is INTEGER
*>          The dimension of the array WORK.
*>          LWORK >= MAX(1,5*MIN(M,N)) for the paths (see comments inside code):
*>             - PATH 1  (M much larger than N, JOBU='N')
*>             - PATH 1t (N much larger than M, JOBVT='N')
*>          LWORK >= MAX(1,3*MIN(M,N) + MAX(M,N),5*MIN(M,N)) for the other paths
*>          For good performance, LWORK should generally be larger.
*>
*>          If LWORK = -1, then a workspace query is assumed; the routine
*>          only calculates the optimal size of the WORK array, returns
*>          this value as the first entry of the WORK array, and no error
*>          message related to LWORK is issued by XERBLA.
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit.
*>          < 0:  if INFO = -i, the i-th argument had an illegal value.
*>          > 0:  if DBDSQR did not converge, INFO specifies how many
*>                superdiagonals of an intermediate bidiagonal form B
*>                did not converge to zero. See the description of WORK
*>                above for details.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date April 2012
*
*> \ingroup doubleGEsing
*
*  =====================================================================
      SUBROUTINE DGESVD( JOBU, JOBVT, M, N, A, LDA, S, U, LDU,
     $                   VT, LDVT, WORK, LWORK, INFO )
*
*  -- LAPACK driver routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     April 2012
*
*     .. Scalar Arguments ..
      CHARACTER          JOBU, JOBVT
      INTEGER            INFO, LDA, LDU, LDVT, LWORK, M, N
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   A( LDA, * ), S( * ), U( LDU, * ),
     $                   VT( LDVT, * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ZERO, ONE
      PARAMETER          ( ZERO = 0.0D0, ONE = 1.0D0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            LQUERY, WNTUA, WNTUAS, WNTUN, WNTUO, WNTUS,
     $                   WNTVA, WNTVAS, WNTVN, WNTVO, WNTVS
      INTEGER            BDSPAC, BLK, CHUNK, I, IE, IERR, IR, ISCL,
     $                   ITAU, ITAUP, ITAUQ, IU, IWORK, LDWRKR, LDWRKU,
     $                   MAXWRK, MINMN, MINWRK, MNTHR, NCU, NCVT, NRU,
     $                   NRVT, WRKBL
      INTEGER            LWORK_DGEQRF, LWORK_DORGQR_N, LWORK_DORGQR_M,
     $                   LWORK_DGEBRD, LWORK_DORGBR_P, LWORK_DORGBR_Q,
     $                   LWORK_DGELQF, LWORK_DORGLQ_N, LWORK_DORGLQ_M
      DOUBLE PRECISION   ANRM, BIGNUM, EPS, SMLNUM
*     ..
*     .. Local Arrays ..
      DOUBLE PRECISION   DUM( 1 )
*     ..
*     .. External Subroutines ..
      EXTERNAL           DBDSQR, DGEBRD, DGELQF, DGEMM, DGEQRF, DLACPY,
     $                   DLASCL, DLASET, DORGBR, DORGLQ, DORGQR, DORMBR,
     $                   XERBLA
*     ..
*     .. External Functions ..
      LOGICAL            LSAME
      INTEGER            ILAENV
      DOUBLE PRECISION   DLAMCH, DLANGE
      EXTERNAL           LSAME, ILAENV, DLAMCH, DLANGE
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, MIN, SQRT
*     ..
*     .. Executable Statements ..
*
*     Test the input arguments
*
      INFO = 0
      MINMN = MIN( M, N )
      WNTUA = LSAME( JOBU, 'A' )
      WNTUS = LSAME( JOBU, 'S' )
      WNTUAS = WNTUA .OR. WNTUS
      WNTUO = LSAME( JOBU, 'O' )
      WNTUN = LSAME( JOBU, 'N' )
      WNTVA = LSAME( JOBVT, 'A' )
      WNTVS = LSAME( JOBVT, 'S' )
      WNTVAS = WNTVA .OR. WNTVS
      WNTVO = LSAME( JOBVT, 'O' )
      WNTVN = LSAME( JOBVT, 'N' )
      LQUERY = ( LWORK.EQ.-1 )
*
      IF( .NOT.( WNTUA .OR. WNTUS .OR. WNTUO .OR. WNTUN ) ) THEN
         INFO = -1
      ELSE IF( .NOT.( WNTVA .OR. WNTVS .OR. WNTVO .OR. WNTVN ) .OR.
     $         ( WNTVO .AND. WNTUO ) ) THEN
         INFO = -2
      ELSE IF( M.LT.0 ) THEN
         INFO = -3
      ELSE IF( N.LT.0 ) THEN
         INFO = -4
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -6
      ELSE IF( LDU.LT.1 .OR. ( WNTUAS .AND. LDU.LT.M ) ) THEN
         INFO = -9
      ELSE IF( LDVT.LT.1 .OR. ( WNTVA .AND. LDVT.LT.N ) .OR.
     $         ( WNTVS .AND. LDVT.LT.MINMN ) ) THEN
         INFO = -11
      END IF
*
*     Compute workspace
*      (Note: Comments in the code beginning "Workspace:" describe the
*       minimal amount of workspace needed at that point in the code,
*       as well as the preferred amount for good performance.
*       NB refers to the optimal block size for the immediately
*       following subroutine, as returned by ILAENV.)
*
      IF( INFO.EQ.0 ) THEN
         MINWRK = 1
         MAXWRK = 1
         IF( M.GE.N .AND. MINMN.GT.0 ) THEN
*
*           Compute space needed for DBDSQR
*
            MNTHR = ILAENV( 6, 'DGESVD', JOBU // JOBVT, M, N, 0, 0 )
            BDSPAC = 5*N
*           Compute space needed for DGEQRF
            CALL DGEQRF( M, N, A, LDA, DUM(1), DUM(1), -1, IERR )
            LWORK_DGEQRF = INT( DUM(1) )
*           Compute space needed for DORGQR
            CALL DORGQR( M, N, N, A, LDA, DUM(1), DUM(1), -1, IERR )
            LWORK_DORGQR_N = INT( DUM(1) )
            CALL DORGQR( M, M, N, A, LDA, DUM(1), DUM(1), -1, IERR )
            LWORK_DORGQR_M = INT( DUM(1) )
*           Compute space needed for DGEBRD
            CALL DGEBRD( N, N, A, LDA, S, DUM(1), DUM(1),
     $                   DUM(1), DUM(1), -1, IERR )
            LWORK_DGEBRD = INT( DUM(1) )
*           Compute space needed for DORGBR P
            CALL DORGBR( 'P', N, N, N, A, LDA, DUM(1),
     $                   DUM(1), -1, IERR )
            LWORK_DORGBR_P = INT( DUM(1) )
*           Compute space needed for DORGBR Q
            CALL DORGBR( 'Q', N, N, N, A, LDA, DUM(1),
     $                   DUM(1), -1, IERR )
            LWORK_DORGBR_Q = INT( DUM(1) )
*
            IF( M.GE.MNTHR ) THEN
               IF( WNTUN ) THEN
*
*                 Path 1 (M much larger than N, JOBU='N')
*
                  MAXWRK = N + LWORK_DGEQRF
                  MAXWRK = MAX( MAXWRK, 3*N + LWORK_DGEBRD )
                  IF( WNTVO .OR. WNTVAS )
     $               MAXWRK = MAX( MAXWRK, 3*N + LWORK_DORGBR_P )
                  MAXWRK = MAX( MAXWRK, BDSPAC )
                  MINWRK = MAX( 4*N, BDSPAC )
               ELSE IF( WNTUO .AND. WNTVN ) THEN
*
*                 Path 2 (M much larger than N, JOBU='O', JOBVT='N')
*
                  WRKBL = N + LWORK_DGEQRF
                  WRKBL = MAX( WRKBL, N + LWORK_DORGQR_N )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DGEBRD )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DORGBR_Q )
                  WRKBL = MAX( WRKBL, BDSPAC )
                  MAXWRK = MAX( N*N + WRKBL, N*N + M*N + N )
                  MINWRK = MAX( 3*N + M, BDSPAC )
               ELSE IF( WNTUO .AND. WNTVAS ) THEN
*
*                 Path 3 (M much larger than N, JOBU='O', JOBVT='S' or
*                 'A')
*
                  WRKBL = N + LWORK_DGEQRF
                  WRKBL = MAX( WRKBL, N + LWORK_DORGQR_N )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DGEBRD )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DORGBR_Q )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DORGBR_P )
                  WRKBL = MAX( WRKBL, BDSPAC )
                  MAXWRK = MAX( N*N + WRKBL, N*N + M*N + N )
                  MINWRK = MAX( 3*N + M, BDSPAC )
               ELSE IF( WNTUS .AND. WNTVN ) THEN
*
*                 Path 4 (M much larger than N, JOBU='S', JOBVT='N')
*
                  WRKBL = N + LWORK_DGEQRF
                  WRKBL = MAX( WRKBL, N + LWORK_DORGQR_N )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DGEBRD )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DORGBR_Q )
                  WRKBL = MAX( WRKBL, BDSPAC )
                  MAXWRK = N*N + WRKBL
                  MINWRK = MAX( 3*N + M, BDSPAC )
               ELSE IF( WNTUS .AND. WNTVO ) THEN
*
*                 Path 5 (M much larger than N, JOBU='S', JOBVT='O')
*
                  WRKBL = N + LWORK_DGEQRF
                  WRKBL = MAX( WRKBL, N + LWORK_DORGQR_N )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DGEBRD )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DORGBR_Q )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DORGBR_P )
                  WRKBL = MAX( WRKBL, BDSPAC )
                  MAXWRK = 2*N*N + WRKBL
                  MINWRK = MAX( 3*N + M, BDSPAC )
               ELSE IF( WNTUS .AND. WNTVAS ) THEN
*
*                 Path 6 (M much larger than N, JOBU='S', JOBVT='S' or
*                 'A')
*
                  WRKBL = N + LWORK_DGEQRF
                  WRKBL = MAX( WRKBL, N + LWORK_DORGQR_N )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DGEBRD )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DORGBR_Q )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DORGBR_P )
                  WRKBL = MAX( WRKBL, BDSPAC )
                  MAXWRK = N*N + WRKBL
                  MINWRK = MAX( 3*N + M, BDSPAC )
               ELSE IF( WNTUA .AND. WNTVN ) THEN
*
*                 Path 7 (M much larger than N, JOBU='A', JOBVT='N')
*
                  WRKBL = N + LWORK_DGEQRF
                  WRKBL = MAX( WRKBL, N + LWORK_DORGQR_M )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DGEBRD )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DORGBR_Q )
                  WRKBL = MAX( WRKBL, BDSPAC )
                  MAXWRK = N*N + WRKBL
                  MINWRK = MAX( 3*N + M, BDSPAC )
               ELSE IF( WNTUA .AND. WNTVO ) THEN
*
*                 Path 8 (M much larger than N, JOBU='A', JOBVT='O')
*
                  WRKBL = N + LWORK_DGEQRF
                  WRKBL = MAX( WRKBL, N + LWORK_DORGQR_M )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DGEBRD )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DORGBR_Q )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DORGBR_P )
                  WRKBL = MAX( WRKBL, BDSPAC )
                  MAXWRK = 2*N*N + WRKBL
                  MINWRK = MAX( 3*N + M, BDSPAC )
               ELSE IF( WNTUA .AND. WNTVAS ) THEN
*
*                 Path 9 (M much larger than N, JOBU='A', JOBVT='S' or
*                 'A')
*
                  WRKBL = N + LWORK_DGEQRF
                  WRKBL = MAX( WRKBL, N + LWORK_DORGQR_M )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DGEBRD )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DORGBR_Q )
                  WRKBL = MAX( WRKBL, 3*N + LWORK_DORGBR_P )
                  WRKBL = MAX( WRKBL, BDSPAC )
                  MAXWRK = N*N + WRKBL
                  MINWRK = MAX( 3*N + M, BDSPAC )
               END IF
            ELSE
*
*              Path 10 (M at least N, but not much larger)
*
               CALL DGEBRD( M, N, A, LDA, S, DUM(1), DUM(1),
     $                   DUM(1), DUM(1), -1, IERR )
               LWORK_DGEBRD = INT( DUM(1) )
               MAXWRK = 3*N + LWORK_DGEBRD
               IF( WNTUS .OR. WNTUO ) THEN
                  CALL DORGBR( 'Q', M, N, N, A, LDA, DUM(1),
     $                   DUM(1), -1, IERR )
                  LWORK_DORGBR_Q = INT( DUM(1) )
                  MAXWRK = MAX( MAXWRK, 3*N + LWORK_DORGBR_Q )
               END IF
               IF( WNTUA ) THEN
                  CALL DORGBR( 'Q', M, M, N, A, LDA, DUM(1),
     $                   DUM(1), -1, IERR )
                  LWORK_DORGBR_Q = INT( DUM(1) )
                  MAXWRK = MAX( MAXWRK, 3*N + LWORK_DORGBR_Q )
               END IF
               IF( .NOT.WNTVN ) THEN
                 MAXWRK = MAX( MAXWRK, 3*N + LWORK_DORGBR_P )
               END IF
               MAXWRK = MAX( MAXWRK, BDSPAC )
               MINWRK = MAX( 3*N + M, BDSPAC )
            END IF
         ELSE IF( MINMN.GT.0 ) THEN
*
*           Compute space needed for DBDSQR
*
            MNTHR = ILAENV( 6, 'DGESVD', JOBU // JOBVT, M, N, 0, 0 )
            BDSPAC = 5*M
*           Compute space needed for DGELQF
            CALL DGELQF( M, N, A, LDA, DUM(1), DUM(1), -1, IERR )
            LWORK_DGELQF = INT( DUM(1) )
*           Compute space needed for DORGLQ
            CALL DORGLQ( N, N, M, DUM(1), N, DUM(1), DUM(1), -1, IERR )
            LWORK_DORGLQ_N = INT( DUM(1) )
            CALL DORGLQ( M, N, M, A, LDA, DUM(1), DUM(1), -1, IERR )
            LWORK_DORGLQ_M = INT( DUM(1) )
*           Compute space needed for DGEBRD
            CALL DGEBRD( M, M, A, LDA, S, DUM(1), DUM(1),
     $                   DUM(1), DUM(1), -1, IERR )
            LWORK_DGEBRD = INT( DUM(1) )
*            Compute space needed for DORGBR P
            CALL DORGBR( 'P', M, M, M, A, N, DUM(1),
     $                   DUM(1), -1, IERR )
            LWORK_DORGBR_P = INT( DUM(1) )
*           Compute space needed for DORGBR Q
            CALL DORGBR( 'Q', M, M, M, A, N, DUM(1),
     $                   DUM(1), -1, IERR )
            LWORK_DORGBR_Q = INT( DUM(1) )
            IF( N.GE.MNTHR ) THEN
               IF( WNTVN ) THEN
*
*                 Path 1t(N much larger than M, JOBVT='N')
*
                  MAXWRK = M + LWORK_DGELQF
                  MAXWRK = MAX( MAXWRK, 3*M + LWORK_DGEBRD )
                  IF( WNTUO .OR. WNTUAS )
     $               MAXWRK = MAX( MAXWRK, 3*M + LWORK_DORGBR_Q )
                  MAXWRK = MAX( MAXWRK, BDSPAC )
                  MINWRK = MAX( 4*M, BDSPAC )
               ELSE IF( WNTVO .AND. WNTUN ) THEN
*
*                 Path 2t(N much larger than M, JOBU='N', JOBVT='O')
*
                  WRKBL = M + LWORK_DGELQF
                  WRKBL = MAX( WRKBL, M + LWORK_DORGLQ_M )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DGEBRD )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DORGBR_P )
                  WRKBL = MAX( WRKBL, BDSPAC )
                  MAXWRK = MAX( M*M + WRKBL, M*M + M*N + M )
                  MINWRK = MAX( 3*M + N, BDSPAC )
               ELSE IF( WNTVO .AND. WNTUAS ) THEN
*
*                 Path 3t(N much larger than M, JOBU='S' or 'A',
*                 JOBVT='O')
*
                  WRKBL = M + LWORK_DGELQF
                  WRKBL = MAX( WRKBL, M + LWORK_DORGLQ_M )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DGEBRD )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DORGBR_P )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DORGBR_Q )
                  WRKBL = MAX( WRKBL, BDSPAC )
                  MAXWRK = MAX( M*M + WRKBL, M*M + M*N + M )
                  MINWRK = MAX( 3*M + N, BDSPAC )
               ELSE IF( WNTVS .AND. WNTUN ) THEN
*
*                 Path 4t(N much larger than M, JOBU='N', JOBVT='S')
*
                  WRKBL = M + LWORK_DGELQF
                  WRKBL = MAX( WRKBL, M + LWORK_DORGLQ_M )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DGEBRD )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DORGBR_P )
                  WRKBL = MAX( WRKBL, BDSPAC )
                  MAXWRK = M*M + WRKBL
                  MINWRK = MAX( 3*M + N, BDSPAC )
               ELSE IF( WNTVS .AND. WNTUO ) THEN
*
*                 Path 5t(N much larger than M, JOBU='O', JOBVT='S')
*
                  WRKBL = M + LWORK_DGELQF
                  WRKBL = MAX( WRKBL, M + LWORK_DORGLQ_M )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DGEBRD )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DORGBR_P )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DORGBR_Q )
                  WRKBL = MAX( WRKBL, BDSPAC )
                  MAXWRK = 2*M*M + WRKBL
                  MINWRK = MAX( 3*M + N, BDSPAC )
               ELSE IF( WNTVS .AND. WNTUAS ) THEN
*
*                 Path 6t(N much larger than M, JOBU='S' or 'A',
*                 JOBVT='S')
*
                  WRKBL = M + LWORK_DGELQF
                  WRKBL = MAX( WRKBL, M + LWORK_DORGLQ_M )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DGEBRD )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DORGBR_P )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DORGBR_Q )
                  WRKBL = MAX( WRKBL, BDSPAC )
                  MAXWRK = M*M + WRKBL
                  MINWRK = MAX( 3*M + N, BDSPAC )
               ELSE IF( WNTVA .AND. WNTUN ) THEN
*
*                 Path 7t(N much larger than M, JOBU='N', JOBVT='A')
*
                  WRKBL = M + LWORK_DGELQF
                  WRKBL = MAX( WRKBL, M + LWORK_DORGLQ_N )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DGEBRD )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DORGBR_P )
                  WRKBL = MAX( WRKBL, BDSPAC )
                  MAXWRK = M*M + WRKBL
                  MINWRK = MAX( 3*M + N, BDSPAC )
               ELSE IF( WNTVA .AND. WNTUO ) THEN
*
*                 Path 8t(N much larger than M, JOBU='O', JOBVT='A')
*
                  WRKBL = M + LWORK_DGELQF
                  WRKBL = MAX( WRKBL, M + LWORK_DORGLQ_N )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DGEBRD )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DORGBR_P )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DORGBR_Q )
                  WRKBL = MAX( WRKBL, BDSPAC )
                  MAXWRK = 2*M*M + WRKBL
                  MINWRK = MAX( 3*M + N, BDSPAC )
               ELSE IF( WNTVA .AND. WNTUAS ) THEN
*
*                 Path 9t(N much larger than M, JOBU='S' or 'A',
*                 JOBVT='A')
*
                  WRKBL = M + LWORK_DGELQF
                  WRKBL = MAX( WRKBL, M + LWORK_DORGLQ_N )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DGEBRD )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DORGBR_P )
                  WRKBL = MAX( WRKBL, 3*M + LWORK_DORGBR_Q )
                  WRKBL = MAX( WRKBL, BDSPAC )
                  MAXWRK = M*M + WRKBL
                  MINWRK = MAX( 3*M + N, BDSPAC )
               END IF
            ELSE
*
*              Path 10t(N greater than M, but not much larger)
*
               CALL DGEBRD( M, N, A, LDA, S, DUM(1), DUM(1),
     $                   DUM(1), DUM(1), -1, IERR )
               LWORK_DGEBRD = INT( DUM(1) )
               MAXWRK = 3*M + LWORK_DGEBRD
               IF( WNTVS .OR. WNTVO ) THEN
*                Compute space needed for DORGBR P
                 CALL DORGBR( 'P', M, N, M, A, N, DUM(1),
     $                   DUM(1), -1, IERR )
                 LWORK_DORGBR_P = INT( DUM(1) )
                 MAXWRK = MAX( MAXWRK, 3*M + LWORK_DORGBR_P )
               END IF
               IF( WNTVA ) THEN
                 CALL DORGBR( 'P', N, N, M, A, N, DUM(1),
     $                   DUM(1), -1, IERR )
                 LWORK_DORGBR_P = INT( DUM(1) )
                 MAXWRK = MAX( MAXWRK, 3*M + LWORK_DORGBR_P )
               END IF
               IF( .NOT.WNTUN ) THEN
                  MAXWRK = MAX( MAXWRK, 3*M + LWORK_DORGBR_Q )
               END IF
               MAXWRK = MAX( MAXWRK, BDSPAC )
               MINWRK = MAX( 3*M + N, BDSPAC )
            END IF
         END IF
         MAXWRK = MAX( MAXWRK, MINWRK )
         WORK( 1 ) = MAXWRK
*
         IF( LWORK.LT.MINWRK .AND. .NOT.LQUERY ) THEN
            INFO = -13
         END IF
      END IF
*
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGESVD', -INFO )
         RETURN
      ELSE IF( LQUERY ) THEN
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( M.EQ.0 .OR. N.EQ.0 ) THEN
         RETURN
      END IF
*
*     Get machine constants
*
      EPS = DLAMCH( 'P' )
      SMLNUM = SQRT( DLAMCH( 'S' ) ) / EPS
      BIGNUM = ONE / SMLNUM
*
*     Scale A if max element outside range [SMLNUM,BIGNUM]
*
      ANRM = DLANGE( 'M', M, N, A, LDA, DUM )
      ISCL = 0
      IF( ANRM.GT.ZERO .AND. ANRM.LT.SMLNUM ) THEN
         ISCL = 1
         CALL DLASCL( 'G', 0, 0, ANRM, SMLNUM, M, N, A, LDA, IERR )
      ELSE IF( ANRM.GT.BIGNUM ) THEN
         ISCL = 1
         CALL DLASCL( 'G', 0, 0, ANRM, BIGNUM, M, N, A, LDA, IERR )
      END IF
*
      IF( M.GE.N ) THEN
*
*        A has at least as many rows as columns. If A has sufficiently
*        more rows than columns, first reduce using the QR
*        decomposition (if sufficient workspace available)
*
         IF( M.GE.MNTHR ) THEN
*
            IF( WNTUN ) THEN
*
*              Path 1 (M much larger than N, JOBU='N')
*              No left singular vectors to be computed
*
               ITAU = 1
               IWORK = ITAU + N
*
*              Compute A=Q*R
*              (Workspace: need 2*N, prefer N + N*NB)
*
               CALL DGEQRF( M, N, A, LDA, WORK( ITAU ), WORK( IWORK ),
     $                      LWORK-IWORK+1, IERR )
*
*              Zero out below R
*
               IF( N .GT. 1 ) THEN
                  CALL DLASET( 'L', N-1, N-1, ZERO, ZERO, A( 2, 1 ),
     $                         LDA )
               END IF
               IE = 1
               ITAUQ = IE + N
               ITAUP = ITAUQ + N
               IWORK = ITAUP + N
*
*              Bidiagonalize R in A
*              (Workspace: need 4*N, prefer 3*N + 2*N*NB)
*
               CALL DGEBRD( N, N, A, LDA, S, WORK( IE ), WORK( ITAUQ ),
     $                      WORK( ITAUP ), WORK( IWORK ), LWORK-IWORK+1,
     $                      IERR )
               NCVT = 0
               IF( WNTVO .OR. WNTVAS ) THEN
*
*                 If right singular vectors desired, generate P'.
*                 (Workspace: need 4*N-1, prefer 3*N + (N-1)*NB)
*
                  CALL DORGBR( 'P', N, N, N, A, LDA, WORK( ITAUP ),
     $                         WORK( IWORK ), LWORK-IWORK+1, IERR )
                  NCVT = N
               END IF
               IWORK = IE + N
*
*              Perform bidiagonal QR iteration, computing right
*              singular vectors of A in A if desired
*              (Workspace: need BDSPAC)
*
               CALL DBDSQR( 'U', N, NCVT, 0, 0, S, WORK( IE ), A, LDA,
     $                      DUM, 1, DUM, 1, WORK( IWORK ), INFO )
*
*              If right singular vectors desired in VT, copy them there
*
               IF( WNTVAS )
     $            CALL DLACPY( 'F', N, N, A, LDA, VT, LDVT )
*
            ELSE IF( WNTUO .AND. WNTVN ) THEN
*
*              Path 2 (M much larger than N, JOBU='O', JOBVT='N')
*              N left singular vectors to be overwritten on A and
*              no right singular vectors to be computed
*
               IF( LWORK.GE.N*N+MAX( 4*N, BDSPAC ) ) THEN
*
*                 Sufficient workspace for a fast algorithm
*
                  IR = 1
                  IF( LWORK.GE.MAX( WRKBL, LDA*N + N ) + LDA*N ) THEN
*
*                    WORK(IU) is LDA by N, WORK(IR) is LDA by N
*
                     LDWRKU = LDA
                     LDWRKR = LDA
                  ELSE IF( LWORK.GE.MAX( WRKBL, LDA*N + N ) + N*N ) THEN
*
*                    WORK(IU) is LDA by N, WORK(IR) is N by N
*
                     LDWRKU = LDA
                     LDWRKR = N
                  ELSE
*
*                    WORK(IU) is LDWRKU by N, WORK(IR) is N by N
*
                     LDWRKU = ( LWORK-N*N-N ) / N
                     LDWRKR = N
                  END IF
                  ITAU = IR + LDWRKR*N
                  IWORK = ITAU + N
*
*                 Compute A=Q*R
*                 (Workspace: need N*N + 2*N, prefer N*N + N + N*NB)
*
                  CALL DGEQRF( M, N, A, LDA, WORK( ITAU ),
     $                         WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                 Copy R to WORK(IR) and zero out below it
*
                  CALL DLACPY( 'U', N, N, A, LDA, WORK( IR ), LDWRKR )
                  CALL DLASET( 'L', N-1, N-1, ZERO, ZERO, WORK( IR+1 ),
     $                         LDWRKR )
*
*                 Generate Q in A
*                 (Workspace: need N*N + 2*N, prefer N*N + N + N*NB)
*
                  CALL DORGQR( M, N, N, A, LDA, WORK( ITAU ),
     $                         WORK( IWORK ), LWORK-IWORK+1, IERR )
                  IE = ITAU
                  ITAUQ = IE + N
                  ITAUP = ITAUQ + N
                  IWORK = ITAUP + N
*
*                 Bidiagonalize R in WORK(IR)
*                 (Workspace: need N*N + 4*N, prefer N*N + 3*N + 2*N*NB)
*
                  CALL DGEBRD( N, N, WORK( IR ), LDWRKR, S, WORK( IE ),
     $                         WORK( ITAUQ ), WORK( ITAUP ),
     $                         WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                 Generate left vectors bidiagonalizing R
*                 (Workspace: need N*N + 4*N, prefer N*N + 3*N + N*NB)
*
                  CALL DORGBR( 'Q', N, N, N, WORK( IR ), LDWRKR,
     $                         WORK( ITAUQ ), WORK( IWORK ),
     $                         LWORK-IWORK+1, IERR )
                  IWORK = IE + N
*
*                 Perform bidiagonal QR iteration, computing left
*                 singular vectors of R in WORK(IR)
*                 (Workspace: need N*N + BDSPAC)
*
                  CALL DBDSQR( 'U', N, 0, N, 0, S, WORK( IE ), DUM, 1,
     $                         WORK( IR ), LDWRKR, DUM, 1,
     $                         WORK( IWORK ), INFO )
                  IU = IE + N
*
*                 Multiply Q in A by left singular vectors of R in
*                 WORK(IR), storing result in WORK(IU) and copying to A
*                 (Workspace: need N*N + 2*N, prefer N*N + M*N + N)
*
                  DO 10 I = 1, M, LDWRKU
                     CHUNK = MIN( M-I+1, LDWRKU )
                     CALL DGEMM( 'N', 'N', CHUNK, N, N, ONE, A( I, 1 ),
     $                           LDA, WORK( IR ), LDWRKR, ZERO,
     $                           WORK( IU ), LDWRKU )
                     CALL DLACPY( 'F', CHUNK, N, WORK( IU ), LDWRKU,
     $                            A( I, 1 ), LDA )
   10             CONTINUE
*
               ELSE
*
*                 Insufficient workspace for a fast algorithm
*
                  IE = 1
                  ITAUQ = IE + N
                  ITAUP = ITAUQ + N
                  IWORK = ITAUP + N
*
*                 Bidiagonalize A
*                 (Workspace: need 3*N + M, prefer 3*N + (M + N)*NB)
*
                  CALL DGEBRD( M, N, A, LDA, S, WORK( IE ),
     $                         WORK( ITAUQ ), WORK( ITAUP ),
     $                         WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                 Generate left vectors bidiagonalizing A
*                 (Workspace: need 4*N, prefer 3*N + N*NB)
*
                  CALL DORGBR( 'Q', M, N, N, A, LDA, WORK( ITAUQ ),
     $                         WORK( IWORK ), LWORK-IWORK+1, IERR )
                  IWORK = IE + N
*
*                 Perform bidiagonal QR iteration, computing left
*                 singular vectors of A in A
*                 (Workspace: need BDSPAC)
*
                  CALL DBDSQR( 'U', N, 0, M, 0, S, WORK( IE ), DUM, 1,
     $                         A, LDA, DUM, 1, WORK( IWORK ), INFO )
*
               END IF
*
            ELSE IF( WNTUO .AND. WNTVAS ) THEN
*
*              Path 3 (M much larger than N, JOBU='O', JOBVT='S' or 'A')
*              N left singular vectors to be overwritten on A and
*              N right singular vectors to be computed in VT
*
               IF( LWORK.GE.N*N+MAX( 4*N, BDSPAC ) ) THEN
*
*                 Sufficient workspace for a fast algorithm
*
                  IR = 1
                  IF( LWORK.GE.MAX( WRKBL, LDA*N + N ) + LDA*N ) THEN
*
*                    WORK(IU) is LDA by N and WORK(IR) is LDA by N
*
                     LDWRKU = LDA
                     LDWRKR = LDA
                  ELSE IF( LWORK.GE.MAX( WRKBL, LDA*N + N ) + N*N ) THEN
*
*                    WORK(IU) is LDA by N and WORK(IR) is N by N
*
                     LDWRKU = LDA
                     LDWRKR = N
                  ELSE
*
*                    WORK(IU) is LDWRKU by N and WORK(IR) is N by N
*
                     LDWRKU = ( LWORK-N*N-N ) / N
                     LDWRKR = N
                  END IF
                  ITAU = IR + LDWRKR*N
                  IWORK = ITAU + N
*
*                 Compute A=Q*R
*                 (Workspace: need N*N + 2*N, prefer N*N + N + N*NB)
*
                  CALL DGEQRF( M, N, A, LDA, WORK( ITAU ),
     $                         WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                 Copy R to VT, zeroing out below it
*
                  CALL DLACPY( 'U', N, N, A, LDA, VT, LDVT )
                  IF( N.GT.1 )
     $               CALL DLASET( 'L', N-1, N-1, ZERO, ZERO,
     $                            VT( 2, 1 ), LDVT )
*
*                 Generate Q in A
*                 (Workspace: need N*N + 2*N, prefer N*N + N + N*NB)
*
                  CALL DORGQR( M, N, N, A, LDA, WORK( ITAU ),
     $                         WORK( IWORK ), LWORK-IWORK+1, IERR )
                  IE = ITAU
                  ITAUQ = IE + N
                  ITAUP = ITAUQ + N
                  IWORK = ITAUP + N
*
*                 Bidiagonalize R in VT, copying result to WORK(IR)
*                 (Workspace: need N*N + 4*N, prefer N*N + 3*N + 2*N*NB)
*
                  CALL DGEBRD( N, N, VT, LDVT, S, WORK( IE ),
     $                         WORK( ITAUQ ), WORK( ITAUP ),
     $                         WORK( IWORK ), LWORK-IWORK+1, IERR )
                  CALL DLACPY( 'L', N, N, VT, LDVT, WORK( IR ), LDWRKR )
*
*                 Generate left vectors bidiagonalizing R in WORK(IR)
*                 (Workspace: need N*N + 4*N, prefer N*N + 3*N + N*NB)
*
                  CALL DORGBR( 'Q', N, N, N, WORK( IR ), LDWRKR,
     $                         WORK( ITAUQ ), WORK( IWORK ),
     $                         LWORK-IWORK+1, IERR )
*
*                 Generate right vectors bidiagonalizing R in VT
*                 (Workspace: need N*N + 4*N-1, prefer N*N + 3*N + (N-1)*NB)
*
                  CALL DORGBR( 'P', N, N, N, VT, LDVT, WORK( ITAUP ),
     $                         WORK( IWORK ), LWORK-IWORK+1, IERR )
                  IWORK = IE + N
*
*                 Perform bidiagonal QR iteration, computing left
*                 singular vectors of R in WORK(IR) and computing right
*                 singular vectors of R in VT
*                 (Workspace: need N*N + BDSPAC)
*
                  CALL DBDSQR( 'U', N, N, N, 0, S, WORK( IE ), VT, LDVT,
     $                         WORK( IR ), LDWRKR, DUM, 1,
     $                         WORK( IWORK ), INFO )
                  IU = IE + N
*
*                 Multiply Q in A by left singular vectors of R in
*                 WORK(IR), storing result in WORK(IU) and copying to A
*                 (Workspace: need N*N + 2*N, prefer N*N + M*N + N)
*
                  DO 20 I = 1, M, LDWRKU
                     CHUNK = MIN( M-I+1, LDWRKU )
                     CALL DGEMM( 'N', 'N', CHUNK, N, N, ONE, A( I, 1 ),
     $                           LDA, WORK( IR ), LDWRKR, ZERO,
     $                           WORK( IU ), LDWRKU )
                     CALL DLACPY( 'F', CHUNK, N, WORK( IU ), LDWRKU,
     $                            A( I, 1 ), LDA )
   20             CONTINUE
*
               ELSE
*
*                 Insufficient workspace for a fast algorithm
*
                  ITAU = 1
                  IWORK = ITAU + N
*
*                 Compute A=Q*R
*                 (Workspace: need 2*N, prefer N + N*NB)
*
                  CALL DGEQRF( M, N, A, LDA, WORK( ITAU ),
     $                         WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                 Copy R to VT, zeroing out below it
*
                  CALL DLACPY( 'U', N, N, A, LDA, VT, LDVT )
                  IF( N.GT.1 )
     $               CALL DLASET( 'L', N-1, N-1, ZERO, ZERO,
     $                            VT( 2, 1 ), LDVT )
*
*                 Generate Q in A
*                 (Workspace: need 2*N, prefer N + N*NB)
*
                  CALL DORGQR( M, N, N, A, LDA, WORK( ITAU ),
     $                         WORK( IWORK ), LWORK-IWORK+1, IERR )
                  IE = ITAU
                  ITAUQ = IE + N
                  ITAUP = ITAUQ + N
                  IWORK = ITAUP + N
*
*                 Bidiagonalize R in VT
*                 (Workspace: need 4*N, prefer 3*N + 2*N*NB)
*
                  CALL DGEBRD( N, N, VT, LDVT, S, WORK( IE ),
     $                         WORK( ITAUQ ), WORK( ITAUP ),
     $                         WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                 Multiply Q in A by left vectors bidiagonalizing R
*                 (Workspace: need 3*N + M, prefer 3*N + M*NB)
*
                  CALL DORMBR( 'Q', 'R', 'N', M, N, N, VT, LDVT,
     $                         WORK( ITAUQ ), A, LDA, WORK( IWORK ),
     $                         LWORK-IWORK+1, IERR )
*
*                 Generate right vectors bidiagonalizing R in VT
*                 (Workspace: need 4*N-1, prefer 3*N + (N-1)*NB)
*
                  CALL DORGBR( 'P', N, N, N, VT, LDVT, WORK( ITAUP ),
     $                         WORK( IWORK ), LWORK-IWORK+1, IERR )
                  IWORK = IE + N
*
*                 Perform bidiagonal QR iteration, computing left
*                 singular vectors of A in A and computing right
*                 singular vectors of A in VT
*                 (Workspace: need BDSPAC)
*
                  CALL DBDSQR( 'U', N, N, M, 0, S, WORK( IE ), VT, LDVT,
     $                         A, LDA, DUM, 1, WORK( IWORK ), INFO )
*
               END IF
*
            ELSE IF( WNTUS ) THEN
*
               IF( WNTVN ) THEN
*
*                 Path 4 (M much larger than N, JOBU='S', JOBVT='N')
*                 N left singular vectors to be computed in U and
*                 no right singular vectors to be computed
*
                  IF( LWORK.GE.N*N+MAX( 4*N, BDSPAC ) ) THEN
*
*                    Sufficient workspace for a fast algorithm
*
                     IR = 1
                     IF( LWORK.GE.WRKBL+LDA*N ) THEN
*
*                       WORK(IR) is LDA by N
*
                        LDWRKR = LDA
                     ELSE
*
*                       WORK(IR) is N by N
*
                        LDWRKR = N
                     END IF
                     ITAU = IR + LDWRKR*N
                     IWORK = ITAU + N
*
*                    Compute A=Q*R
*                    (Workspace: need N*N + 2*N, prefer N*N + N + N*NB)
*
                     CALL DGEQRF( M, N, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Copy R to WORK(IR), zeroing out below it
*
                     CALL DLACPY( 'U', N, N, A, LDA, WORK( IR ),
     $                            LDWRKR )
                     CALL DLASET( 'L', N-1, N-1, ZERO, ZERO,
     $                            WORK( IR+1 ), LDWRKR )
*
*                    Generate Q in A
*                    (Workspace: need N*N + 2*N, prefer N*N + N + N*NB)
*
                     CALL DORGQR( M, N, N, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IE = ITAU
                     ITAUQ = IE + N
                     ITAUP = ITAUQ + N
                     IWORK = ITAUP + N
*
*                    Bidiagonalize R in WORK(IR)
*                    (Workspace: need N*N + 4*N, prefer N*N + 3*N + 2*N*NB)
*
                     CALL DGEBRD( N, N, WORK( IR ), LDWRKR, S,
     $                            WORK( IE ), WORK( ITAUQ ),
     $                            WORK( ITAUP ), WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
*
*                    Generate left vectors bidiagonalizing R in WORK(IR)
*                    (Workspace: need N*N + 4*N, prefer N*N + 3*N + N*NB)
*
                     CALL DORGBR( 'Q', N, N, N, WORK( IR ), LDWRKR,
     $                            WORK( ITAUQ ), WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
                     IWORK = IE + N
*
*                    Perform bidiagonal QR iteration, computing left
*                    singular vectors of R in WORK(IR)
*                    (Workspace: need N*N + BDSPAC)
*
                     CALL DBDSQR( 'U', N, 0, N, 0, S, WORK( IE ), DUM,
     $                            1, WORK( IR ), LDWRKR, DUM, 1,
     $                            WORK( IWORK ), INFO )
*
*                    Multiply Q in A by left singular vectors of R in
*                    WORK(IR), storing result in U
*                    (Workspace: need N*N)
*
                     CALL DGEMM( 'N', 'N', M, N, N, ONE, A, LDA,
     $                           WORK( IR ), LDWRKR, ZERO, U, LDU )
*
                  ELSE
*
*                    Insufficient workspace for a fast algorithm
*
                     ITAU = 1
                     IWORK = ITAU + N
*
*                    Compute A=Q*R, copying result to U
*                    (Workspace: need 2*N, prefer N + N*NB)
*
                     CALL DGEQRF( M, N, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     CALL DLACPY( 'L', M, N, A, LDA, U, LDU )
*
*                    Generate Q in U
*                    (Workspace: need 2*N, prefer N + N*NB)
*
                     CALL DORGQR( M, N, N, U, LDU, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IE = ITAU
                     ITAUQ = IE + N
                     ITAUP = ITAUQ + N
                     IWORK = ITAUP + N
*
*                    Zero out below R in A
*
                     IF( N .GT. 1 ) THEN
                        CALL DLASET( 'L', N-1, N-1, ZERO, ZERO,
     $                               A( 2, 1 ), LDA )
                     END IF
*
*                    Bidiagonalize R in A
*                    (Workspace: need 4*N, prefer 3*N + 2*N*NB)
*
                     CALL DGEBRD( N, N, A, LDA, S, WORK( IE ),
     $                            WORK( ITAUQ ), WORK( ITAUP ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Multiply Q in U by left vectors bidiagonalizing R
*                    (Workspace: need 3*N + M, prefer 3*N + M*NB)
*
                     CALL DORMBR( 'Q', 'R', 'N', M, N, N, A, LDA,
     $                            WORK( ITAUQ ), U, LDU, WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
                     IWORK = IE + N
*
*                    Perform bidiagonal QR iteration, computing left
*                    singular vectors of A in U
*                    (Workspace: need BDSPAC)
*
                     CALL DBDSQR( 'U', N, 0, M, 0, S, WORK( IE ), DUM,
     $                            1, U, LDU, DUM, 1, WORK( IWORK ),
     $                            INFO )
*
                  END IF
*
               ELSE IF( WNTVO ) THEN
*
*                 Path 5 (M much larger than N, JOBU='S', JOBVT='O')
*                 N left singular vectors to be computed in U and
*                 N right singular vectors to be overwritten on A
*
                  IF( LWORK.GE.2*N*N+MAX( 4*N, BDSPAC ) ) THEN
*
*                    Sufficient workspace for a fast algorithm
*
                     IU = 1
                     IF( LWORK.GE.WRKBL+2*LDA*N ) THEN
*
*                       WORK(IU) is LDA by N and WORK(IR) is LDA by N
*
                        LDWRKU = LDA
                        IR = IU + LDWRKU*N
                        LDWRKR = LDA
                     ELSE IF( LWORK.GE.WRKBL+( LDA + N )*N ) THEN
*
*                       WORK(IU) is LDA by N and WORK(IR) is N by N
*
                        LDWRKU = LDA
                        IR = IU + LDWRKU*N
                        LDWRKR = N
                     ELSE
*
*                       WORK(IU) is N by N and WORK(IR) is N by N
*
                        LDWRKU = N
                        IR = IU + LDWRKU*N
                        LDWRKR = N
                     END IF
                     ITAU = IR + LDWRKR*N
                     IWORK = ITAU + N
*
*                    Compute A=Q*R
*                    (Workspace: need 2*N*N + 2*N, prefer 2*N*N + N + N*NB)
*
                     CALL DGEQRF( M, N, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Copy R to WORK(IU), zeroing out below it
*
                     CALL DLACPY( 'U', N, N, A, LDA, WORK( IU ),
     $                            LDWRKU )
                     CALL DLASET( 'L', N-1, N-1, ZERO, ZERO,
     $                            WORK( IU+1 ), LDWRKU )
*
*                    Generate Q in A
*                    (Workspace: need 2*N*N + 2*N, prefer 2*N*N + N + N*NB)
*
                     CALL DORGQR( M, N, N, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IE = ITAU
                     ITAUQ = IE + N
                     ITAUP = ITAUQ + N
                     IWORK = ITAUP + N
*
*                    Bidiagonalize R in WORK(IU), copying result to
*                    WORK(IR)
*                    (Workspace: need 2*N*N + 4*N,
*                                prefer 2*N*N+3*N+2*N*NB)
*
                     CALL DGEBRD( N, N, WORK( IU ), LDWRKU, S,
     $                            WORK( IE ), WORK( ITAUQ ),
     $                            WORK( ITAUP ), WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
                     CALL DLACPY( 'U', N, N, WORK( IU ), LDWRKU,
     $                            WORK( IR ), LDWRKR )
*
*                    Generate left bidiagonalizing vectors in WORK(IU)
*                    (Workspace: need 2*N*N + 4*N, prefer 2*N*N + 3*N + N*NB)
*
                     CALL DORGBR( 'Q', N, N, N, WORK( IU ), LDWRKU,
     $                            WORK( ITAUQ ), WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
*
*                    Generate right bidiagonalizing vectors in WORK(IR)
*                    (Workspace: need 2*N*N + 4*N-1,
*                                prefer 2*N*N+3*N+(N-1)*NB)
*
                     CALL DORGBR( 'P', N, N, N, WORK( IR ), LDWRKR,
     $                            WORK( ITAUP ), WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
                     IWORK = IE + N
*
*                    Perform bidiagonal QR iteration, computing left
*                    singular vectors of R in WORK(IU) and computing
*                    right singular vectors of R in WORK(IR)
*                    (Workspace: need 2*N*N + BDSPAC)
*
                     CALL DBDSQR( 'U', N, N, N, 0, S, WORK( IE ),
     $                            WORK( IR ), LDWRKR, WORK( IU ),
     $                            LDWRKU, DUM, 1, WORK( IWORK ), INFO )
*
*                    Multiply Q in A by left singular vectors of R in
*                    WORK(IU), storing result in U
*                    (Workspace: need N*N)
*
                     CALL DGEMM( 'N', 'N', M, N, N, ONE, A, LDA,
     $                           WORK( IU ), LDWRKU, ZERO, U, LDU )
*
*                    Copy right singular vectors of R to A
*                    (Workspace: need N*N)
*
                     CALL DLACPY( 'F', N, N, WORK( IR ), LDWRKR, A,
     $                            LDA )
*
                  ELSE
*
*                    Insufficient workspace for a fast algorithm
*
                     ITAU = 1
                     IWORK = ITAU + N
*
*                    Compute A=Q*R, copying result to U
*                    (Workspace: need 2*N, prefer N + N*NB)
*
                     CALL DGEQRF( M, N, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     CALL DLACPY( 'L', M, N, A, LDA, U, LDU )
*
*                    Generate Q in U
*                    (Workspace: need 2*N, prefer N + N*NB)
*
                     CALL DORGQR( M, N, N, U, LDU, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IE = ITAU
                     ITAUQ = IE + N
                     ITAUP = ITAUQ + N
                     IWORK = ITAUP + N
*
*                    Zero out below R in A
*
                     IF( N .GT. 1 ) THEN
                        CALL DLASET( 'L', N-1, N-1, ZERO, ZERO,
     $                               A( 2, 1 ), LDA )
                     END IF
*
*                    Bidiagonalize R in A
*                    (Workspace: need 4*N, prefer 3*N + 2*N*NB)
*
                     CALL DGEBRD( N, N, A, LDA, S, WORK( IE ),
     $                            WORK( ITAUQ ), WORK( ITAUP ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Multiply Q in U by left vectors bidiagonalizing R
*                    (Workspace: need 3*N + M, prefer 3*N + M*NB)
*
                     CALL DORMBR( 'Q', 'R', 'N', M, N, N, A, LDA,
     $                            WORK( ITAUQ ), U, LDU, WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
*
*                    Generate right vectors bidiagonalizing R in A
*                    (Workspace: need 4*N-1, prefer 3*N + (N-1)*NB)
*
                     CALL DORGBR( 'P', N, N, N, A, LDA, WORK( ITAUP ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IWORK = IE + N
*
*                    Perform bidiagonal QR iteration, computing left
*                    singular vectors of A in U and computing right
*                    singular vectors of A in A
*                    (Workspace: need BDSPAC)
*
                     CALL DBDSQR( 'U', N, N, M, 0, S, WORK( IE ), A,
     $                            LDA, U, LDU, DUM, 1, WORK( IWORK ),
     $                            INFO )
*
                  END IF
*
               ELSE IF( WNTVAS ) THEN
*
*                 Path 6 (M much larger than N, JOBU='S', JOBVT='S'
*                         or 'A')
*                 N left singular vectors to be computed in U and
*                 N right singular vectors to be computed in VT
*
                  IF( LWORK.GE.N*N+MAX( 4*N, BDSPAC ) ) THEN
*
*                    Sufficient workspace for a fast algorithm
*
                     IU = 1
                     IF( LWORK.GE.WRKBL+LDA*N ) THEN
*
*                       WORK(IU) is LDA by N
*
                        LDWRKU = LDA
                     ELSE
*
*                       WORK(IU) is N by N
*
                        LDWRKU = N
                     END IF
                     ITAU = IU + LDWRKU*N
                     IWORK = ITAU + N
*
*                    Compute A=Q*R
*                    (Workspace: need N*N + 2*N, prefer N*N + N + N*NB)
*
                     CALL DGEQRF( M, N, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Copy R to WORK(IU), zeroing out below it
*
                     CALL DLACPY( 'U', N, N, A, LDA, WORK( IU ),
     $                            LDWRKU )
                     CALL DLASET( 'L', N-1, N-1, ZERO, ZERO,
     $                            WORK( IU+1 ), LDWRKU )
*
*                    Generate Q in A
*                    (Workspace: need N*N + 2*N, prefer N*N + N + N*NB)
*
                     CALL DORGQR( M, N, N, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IE = ITAU
                     ITAUQ = IE + N
                     ITAUP = ITAUQ + N
                     IWORK = ITAUP + N
*
*                    Bidiagonalize R in WORK(IU), copying result to VT
*                    (Workspace: need N*N + 4*N, prefer N*N + 3*N + 2*N*NB)
*
                     CALL DGEBRD( N, N, WORK( IU ), LDWRKU, S,
     $                            WORK( IE ), WORK( ITAUQ ),
     $                            WORK( ITAUP ), WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
                     CALL DLACPY( 'U', N, N, WORK( IU ), LDWRKU, VT,
     $                            LDVT )
*
*                    Generate left bidiagonalizing vectors in WORK(IU)
*                    (Workspace: need N*N + 4*N, prefer N*N + 3*N + N*NB)
*
                     CALL DORGBR( 'Q', N, N, N, WORK( IU ), LDWRKU,
     $                            WORK( ITAUQ ), WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
*
*                    Generate right bidiagonalizing vectors in VT
*                    (Workspace: need N*N + 4*N-1,
*                                prefer N*N+3*N+(N-1)*NB)
*
                     CALL DORGBR( 'P', N, N, N, VT, LDVT, WORK( ITAUP ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IWORK = IE + N
*
*                    Perform bidiagonal QR iteration, computing left
*                    singular vectors of R in WORK(IU) and computing
*                    right singular vectors of R in VT
*                    (Workspace: need N*N + BDSPAC)
*
                     CALL DBDSQR( 'U', N, N, N, 0, S, WORK( IE ), VT,
     $                            LDVT, WORK( IU ), LDWRKU, DUM, 1,
     $                            WORK( IWORK ), INFO )
*
*                    Multiply Q in A by left singular vectors of R in
*                    WORK(IU), storing result in U
*                    (Workspace: need N*N)
*
                     CALL DGEMM( 'N', 'N', M, N, N, ONE, A, LDA,
     $                           WORK( IU ), LDWRKU, ZERO, U, LDU )
*
                  ELSE
*
*                    Insufficient workspace for a fast algorithm
*
                     ITAU = 1
                     IWORK = ITAU + N
*
*                    Compute A=Q*R, copying result to U
*                    (Workspace: need 2*N, prefer N + N*NB)
*
                     CALL DGEQRF( M, N, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     CALL DLACPY( 'L', M, N, A, LDA, U, LDU )
*
*                    Generate Q in U
*                    (Workspace: need 2*N, prefer N + N*NB)
*
                     CALL DORGQR( M, N, N, U, LDU, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Copy R to VT, zeroing out below it
*
                     CALL DLACPY( 'U', N, N, A, LDA, VT, LDVT )
                     IF( N.GT.1 )
     $                  CALL DLASET( 'L', N-1, N-1, ZERO, ZERO,
     $                               VT( 2, 1 ), LDVT )
                     IE = ITAU
                     ITAUQ = IE + N
                     ITAUP = ITAUQ + N
                     IWORK = ITAUP + N
*
*                    Bidiagonalize R in VT
*                    (Workspace: need 4*N, prefer 3*N + 2*N*NB)
*
                     CALL DGEBRD( N, N, VT, LDVT, S, WORK( IE ),
     $                            WORK( ITAUQ ), WORK( ITAUP ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Multiply Q in U by left bidiagonalizing vectors
*                    in VT
*                    (Workspace: need 3*N + M, prefer 3*N + M*NB)
*
                     CALL DORMBR( 'Q', 'R', 'N', M, N, N, VT, LDVT,
     $                            WORK( ITAUQ ), U, LDU, WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
*
*                    Generate right bidiagonalizing vectors in VT
*                    (Workspace: need 4*N-1, prefer 3*N + (N-1)*NB)
*
                     CALL DORGBR( 'P', N, N, N, VT, LDVT, WORK( ITAUP ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IWORK = IE + N
*
*                    Perform bidiagonal QR iteration, computing left
*                    singular vectors of A in U and computing right
*                    singular vectors of A in VT
*                    (Workspace: need BDSPAC)
*
                     CALL DBDSQR( 'U', N, N, M, 0, S, WORK( IE ), VT,
     $                            LDVT, U, LDU, DUM, 1, WORK( IWORK ),
     $                            INFO )
*
                  END IF
*
               END IF
*
            ELSE IF( WNTUA ) THEN
*
               IF( WNTVN ) THEN
*
*                 Path 7 (M much larger than N, JOBU='A', JOBVT='N')
*                 M left singular vectors to be computed in U and
*                 no right singular vectors to be computed
*
                  IF( LWORK.GE.N*N+MAX( N+M, 4*N, BDSPAC ) ) THEN
*
*                    Sufficient workspace for a fast algorithm
*
                     IR = 1
                     IF( LWORK.GE.WRKBL+LDA*N ) THEN
*
*                       WORK(IR) is LDA by N
*
                        LDWRKR = LDA
                     ELSE
*
*                       WORK(IR) is N by N
*
                        LDWRKR = N
                     END IF
                     ITAU = IR + LDWRKR*N
                     IWORK = ITAU + N
*
*                    Compute A=Q*R, copying result to U
*                    (Workspace: need N*N + 2*N, prefer N*N + N + N*NB)
*
                     CALL DGEQRF( M, N, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     CALL DLACPY( 'L', M, N, A, LDA, U, LDU )
*
*                    Copy R to WORK(IR), zeroing out below it
*
                     CALL DLACPY( 'U', N, N, A, LDA, WORK( IR ),
     $                            LDWRKR )
                     CALL DLASET( 'L', N-1, N-1, ZERO, ZERO,
     $                            WORK( IR+1 ), LDWRKR )
*
*                    Generate Q in U
*                    (Workspace: need N*N + N + M, prefer N*N + N + M*NB)
*
                     CALL DORGQR( M, M, N, U, LDU, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IE = ITAU
                     ITAUQ = IE + N
                     ITAUP = ITAUQ + N
                     IWORK = ITAUP + N
*
*                    Bidiagonalize R in WORK(IR)
*                    (Workspace: need N*N + 4*N, prefer N*N + 3*N + 2*N*NB)
*
                     CALL DGEBRD( N, N, WORK( IR ), LDWRKR, S,
     $                            WORK( IE ), WORK( ITAUQ ),
     $                            WORK( ITAUP ), WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
*
*                    Generate left bidiagonalizing vectors in WORK(IR)
*                    (Workspace: need N*N + 4*N, prefer N*N + 3*N + N*NB)
*
                     CALL DORGBR( 'Q', N, N, N, WORK( IR ), LDWRKR,
     $                            WORK( ITAUQ ), WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
                     IWORK = IE + N
*
*                    Perform bidiagonal QR iteration, computing left
*                    singular vectors of R in WORK(IR)
*                    (Workspace: need N*N + BDSPAC)
*
                     CALL DBDSQR( 'U', N, 0, N, 0, S, WORK( IE ), DUM,
     $                            1, WORK( IR ), LDWRKR, DUM, 1,
     $                            WORK( IWORK ), INFO )
*
*                    Multiply Q in U by left singular vectors of R in
*                    WORK(IR), storing result in A
*                    (Workspace: need N*N)
*
                     CALL DGEMM( 'N', 'N', M, N, N, ONE, U, LDU,
     $                           WORK( IR ), LDWRKR, ZERO, A, LDA )
*
*                    Copy left singular vectors of A from A to U
*
                     CALL DLACPY( 'F', M, N, A, LDA, U, LDU )
*
                  ELSE
*
*                    Insufficient workspace for a fast algorithm
*
                     ITAU = 1
                     IWORK = ITAU + N
*
*                    Compute A=Q*R, copying result to U
*                    (Workspace: need 2*N, prefer N + N*NB)
*
                     CALL DGEQRF( M, N, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     CALL DLACPY( 'L', M, N, A, LDA, U, LDU )
*
*                    Generate Q in U
*                    (Workspace: need N + M, prefer N + M*NB)
*
                     CALL DORGQR( M, M, N, U, LDU, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IE = ITAU
                     ITAUQ = IE + N
                     ITAUP = ITAUQ + N
                     IWORK = ITAUP + N
*
*                    Zero out below R in A
*
                     IF( N .GT. 1 ) THEN
                        CALL DLASET( 'L', N-1, N-1, ZERO, ZERO,
     $                                A( 2, 1 ), LDA )
                     END IF
*
*                    Bidiagonalize R in A
*                    (Workspace: need 4*N, prefer 3*N + 2*N*NB)
*
                     CALL DGEBRD( N, N, A, LDA, S, WORK( IE ),
     $                            WORK( ITAUQ ), WORK( ITAUP ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Multiply Q in U by left bidiagonalizing vectors
*                    in A
*                    (Workspace: need 3*N + M, prefer 3*N + M*NB)
*
                     CALL DORMBR( 'Q', 'R', 'N', M, N, N, A, LDA,
     $                            WORK( ITAUQ ), U, LDU, WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
                     IWORK = IE + N
*
*                    Perform bidiagonal QR iteration, computing left
*                    singular vectors of A in U
*                    (Workspace: need BDSPAC)
*
                     CALL DBDSQR( 'U', N, 0, M, 0, S, WORK( IE ), DUM,
     $                            1, U, LDU, DUM, 1, WORK( IWORK ),
     $                            INFO )
*
                  END IF
*
               ELSE IF( WNTVO ) THEN
*
*                 Path 8 (M much larger than N, JOBU='A', JOBVT='O')
*                 M left singular vectors to be computed in U and
*                 N right singular vectors to be overwritten on A
*
                  IF( LWORK.GE.2*N*N+MAX( N+M, 4*N, BDSPAC ) ) THEN
*
*                    Sufficient workspace for a fast algorithm
*
                     IU = 1
                     IF( LWORK.GE.WRKBL+2*LDA*N ) THEN
*
*                       WORK(IU) is LDA by N and WORK(IR) is LDA by N
*
                        LDWRKU = LDA
                        IR = IU + LDWRKU*N
                        LDWRKR = LDA
                     ELSE IF( LWORK.GE.WRKBL+( LDA + N )*N ) THEN
*
*                       WORK(IU) is LDA by N and WORK(IR) is N by N
*
                        LDWRKU = LDA
                        IR = IU + LDWRKU*N
                        LDWRKR = N
                     ELSE
*
*                       WORK(IU) is N by N and WORK(IR) is N by N
*
                        LDWRKU = N
                        IR = IU + LDWRKU*N
                        LDWRKR = N
                     END IF
                     ITAU = IR + LDWRKR*N
                     IWORK = ITAU + N
*
*                    Compute A=Q*R, copying result to U
*                    (Workspace: need 2*N*N + 2*N, prefer 2*N*N + N + N*NB)
*
                     CALL DGEQRF( M, N, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     CALL DLACPY( 'L', M, N, A, LDA, U, LDU )
*
*                    Generate Q in U
*                    (Workspace: need 2*N*N + N + M, prefer 2*N*N + N + M*NB)
*
                     CALL DORGQR( M, M, N, U, LDU, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Copy R to WORK(IU), zeroing out below it
*
                     CALL DLACPY( 'U', N, N, A, LDA, WORK( IU ),
     $                            LDWRKU )
                     CALL DLASET( 'L', N-1, N-1, ZERO, ZERO,
     $                            WORK( IU+1 ), LDWRKU )
                     IE = ITAU
                     ITAUQ = IE + N
                     ITAUP = ITAUQ + N
                     IWORK = ITAUP + N
*
*                    Bidiagonalize R in WORK(IU), copying result to
*                    WORK(IR)
*                    (Workspace: need 2*N*N + 4*N,
*                                prefer 2*N*N+3*N+2*N*NB)
*
                     CALL DGEBRD( N, N, WORK( IU ), LDWRKU, S,
     $                            WORK( IE ), WORK( ITAUQ ),
     $                            WORK( ITAUP ), WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
                     CALL DLACPY( 'U', N, N, WORK( IU ), LDWRKU,
     $                            WORK( IR ), LDWRKR )
*
*                    Generate left bidiagonalizing vectors in WORK(IU)
*                    (Workspace: need 2*N*N + 4*N, prefer 2*N*N + 3*N + N*NB)
*
                     CALL DORGBR( 'Q', N, N, N, WORK( IU ), LDWRKU,
     $                            WORK( ITAUQ ), WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
*
*                    Generate right bidiagonalizing vectors in WORK(IR)
*                    (Workspace: need 2*N*N + 4*N-1,
*                                prefer 2*N*N+3*N+(N-1)*NB)
*
                     CALL DORGBR( 'P', N, N, N, WORK( IR ), LDWRKR,
     $                            WORK( ITAUP ), WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
                     IWORK = IE + N
*
*                    Perform bidiagonal QR iteration, computing left
*                    singular vectors of R in WORK(IU) and computing
*                    right singular vectors of R in WORK(IR)
*                    (Workspace: need 2*N*N + BDSPAC)
*
                     CALL DBDSQR( 'U', N, N, N, 0, S, WORK( IE ),
     $                            WORK( IR ), LDWRKR, WORK( IU ),
     $                            LDWRKU, DUM, 1, WORK( IWORK ), INFO )
*
*                    Multiply Q in U by left singular vectors of R in
*                    WORK(IU), storing result in A
*                    (Workspace: need N*N)
*
                     CALL DGEMM( 'N', 'N', M, N, N, ONE, U, LDU,
     $                           WORK( IU ), LDWRKU, ZERO, A, LDA )
*
*                    Copy left singular vectors of A from A to U
*
                     CALL DLACPY( 'F', M, N, A, LDA, U, LDU )
*
*                    Copy right singular vectors of R from WORK(IR) to A
*
                     CALL DLACPY( 'F', N, N, WORK( IR ), LDWRKR, A,
     $                            LDA )
*
                  ELSE
*
*                    Insufficient workspace for a fast algorithm
*
                     ITAU = 1
                     IWORK = ITAU + N
*
*                    Compute A=Q*R, copying result to U
*                    (Workspace: need 2*N, prefer N + N*NB)
*
                     CALL DGEQRF( M, N, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     CALL DLACPY( 'L', M, N, A, LDA, U, LDU )
*
*                    Generate Q in U
*                    (Workspace: need N + M, prefer N + M*NB)
*
                     CALL DORGQR( M, M, N, U, LDU, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IE = ITAU
                     ITAUQ = IE + N
                     ITAUP = ITAUQ + N
                     IWORK = ITAUP + N
*
*                    Zero out below R in A
*
                     IF( N .GT. 1 ) THEN
                        CALL DLASET( 'L', N-1, N-1, ZERO, ZERO,
     $                                A( 2, 1 ), LDA )
                     END IF
*
*                    Bidiagonalize R in A
*                    (Workspace: need 4*N, prefer 3*N + 2*N*NB)
*
                     CALL DGEBRD( N, N, A, LDA, S, WORK( IE ),
     $                            WORK( ITAUQ ), WORK( ITAUP ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Multiply Q in U by left bidiagonalizing vectors
*                    in A
*                    (Workspace: need 3*N + M, prefer 3*N + M*NB)
*
                     CALL DORMBR( 'Q', 'R', 'N', M, N, N, A, LDA,
     $                            WORK( ITAUQ ), U, LDU, WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
*
*                    Generate right bidiagonalizing vectors in A
*                    (Workspace: need 4*N-1, prefer 3*N + (N-1)*NB)
*
                     CALL DORGBR( 'P', N, N, N, A, LDA, WORK( ITAUP ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IWORK = IE + N
*
*                    Perform bidiagonal QR iteration, computing left
*                    singular vectors of A in U and computing right
*                    singular vectors of A in A
*                    (Workspace: need BDSPAC)
*
                     CALL DBDSQR( 'U', N, N, M, 0, S, WORK( IE ), A,
     $                            LDA, U, LDU, DUM, 1, WORK( IWORK ),
     $                            INFO )
*
                  END IF
*
               ELSE IF( WNTVAS ) THEN
*
*                 Path 9 (M much larger than N, JOBU='A', JOBVT='S'
*                         or 'A')
*                 M left singular vectors to be computed in U and
*                 N right singular vectors to be computed in VT
*
                  IF( LWORK.GE.N*N+MAX( N+M, 4*N, BDSPAC ) ) THEN
*
*                    Sufficient workspace for a fast algorithm
*
                     IU = 1
                     IF( LWORK.GE.WRKBL+LDA*N ) THEN
*
*                       WORK(IU) is LDA by N
*
                        LDWRKU = LDA
                     ELSE
*
*                       WORK(IU) is N by N
*
                        LDWRKU = N
                     END IF
                     ITAU = IU + LDWRKU*N
                     IWORK = ITAU + N
*
*                    Compute A=Q*R, copying result to U
*                    (Workspace: need N*N + 2*N, prefer N*N + N + N*NB)
*
                     CALL DGEQRF( M, N, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     CALL DLACPY( 'L', M, N, A, LDA, U, LDU )
*
*                    Generate Q in U
*                    (Workspace: need N*N + N + M, prefer N*N + N + M*NB)
*
                     CALL DORGQR( M, M, N, U, LDU, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Copy R to WORK(IU), zeroing out below it
*
                     CALL DLACPY( 'U', N, N, A, LDA, WORK( IU ),
     $                            LDWRKU )
                     CALL DLASET( 'L', N-1, N-1, ZERO, ZERO,
     $                            WORK( IU+1 ), LDWRKU )
                     IE = ITAU
                     ITAUQ = IE + N
                     ITAUP = ITAUQ + N
                     IWORK = ITAUP + N
*
*                    Bidiagonalize R in WORK(IU), copying result to VT
*                    (Workspace: need N*N + 4*N, prefer N*N + 3*N + 2*N*NB)
*
                     CALL DGEBRD( N, N, WORK( IU ), LDWRKU, S,
     $                            WORK( IE ), WORK( ITAUQ ),
     $                            WORK( ITAUP ), WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
                     CALL DLACPY( 'U', N, N, WORK( IU ), LDWRKU, VT,
     $                            LDVT )
*
*                    Generate left bidiagonalizing vectors in WORK(IU)
*                    (Workspace: need N*N + 4*N, prefer N*N + 3*N + N*NB)
*
                     CALL DORGBR( 'Q', N, N, N, WORK( IU ), LDWRKU,
     $                            WORK( ITAUQ ), WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
*
*                    Generate right bidiagonalizing vectors in VT
*                    (Workspace: need N*N + 4*N-1,
*                                prefer N*N+3*N+(N-1)*NB)
*
                     CALL DORGBR( 'P', N, N, N, VT, LDVT, WORK( ITAUP ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IWORK = IE + N
*
*                    Perform bidiagonal QR iteration, computing left
*                    singular vectors of R in WORK(IU) and computing
*                    right singular vectors of R in VT
*                    (Workspace: need N*N + BDSPAC)
*
                     CALL DBDSQR( 'U', N, N, N, 0, S, WORK( IE ), VT,
     $                            LDVT, WORK( IU ), LDWRKU, DUM, 1,
     $                            WORK( IWORK ), INFO )
*
*                    Multiply Q in U by left singular vectors of R in
*                    WORK(IU), storing result in A
*                    (Workspace: need N*N)
*
                     CALL DGEMM( 'N', 'N', M, N, N, ONE, U, LDU,
     $                           WORK( IU ), LDWRKU, ZERO, A, LDA )
*
*                    Copy left singular vectors of A from A to U
*
                     CALL DLACPY( 'F', M, N, A, LDA, U, LDU )
*
                  ELSE
*
*                    Insufficient workspace for a fast algorithm
*
                     ITAU = 1
                     IWORK = ITAU + N
*
*                    Compute A=Q*R, copying result to U
*                    (Workspace: need 2*N, prefer N + N*NB)
*
                     CALL DGEQRF( M, N, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     CALL DLACPY( 'L', M, N, A, LDA, U, LDU )
*
*                    Generate Q in U
*                    (Workspace: need N + M, prefer N + M*NB)
*
                     CALL DORGQR( M, M, N, U, LDU, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Copy R from A to VT, zeroing out below it
*
                     CALL DLACPY( 'U', N, N, A, LDA, VT, LDVT )
                     IF( N.GT.1 )
     $                  CALL DLASET( 'L', N-1, N-1, ZERO, ZERO,
     $                               VT( 2, 1 ), LDVT )
                     IE = ITAU
                     ITAUQ = IE + N
                     ITAUP = ITAUQ + N
                     IWORK = ITAUP + N
*
*                    Bidiagonalize R in VT
*                    (Workspace: need 4*N, prefer 3*N + 2*N*NB)
*
                     CALL DGEBRD( N, N, VT, LDVT, S, WORK( IE ),
     $                            WORK( ITAUQ ), WORK( ITAUP ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Multiply Q in U by left bidiagonalizing vectors
*                    in VT
*                    (Workspace: need 3*N + M, prefer 3*N + M*NB)
*
                     CALL DORMBR( 'Q', 'R', 'N', M, N, N, VT, LDVT,
     $                            WORK( ITAUQ ), U, LDU, WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
*
*                    Generate right bidiagonalizing vectors in VT
*                    (Workspace: need 4*N-1, prefer 3*N + (N-1)*NB)
*
                     CALL DORGBR( 'P', N, N, N, VT, LDVT, WORK( ITAUP ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IWORK = IE + N
*
*                    Perform bidiagonal QR iteration, computing left
*                    singular vectors of A in U and computing right
*                    singular vectors of A in VT
*                    (Workspace: need BDSPAC)
*
                     CALL DBDSQR( 'U', N, N, M, 0, S, WORK( IE ), VT,
     $                            LDVT, U, LDU, DUM, 1, WORK( IWORK ),
     $                            INFO )
*
                  END IF
*
               END IF
*
            END IF
*
         ELSE
*
*           M .LT. MNTHR
*
*           Path 10 (M at least N, but not much larger)
*           Reduce to bidiagonal form without QR decomposition
*
            IE = 1
            ITAUQ = IE + N
            ITAUP = ITAUQ + N
            IWORK = ITAUP + N
*
*           Bidiagonalize A
*           (Workspace: need 3*N + M, prefer 3*N + (M + N)*NB)
*
            CALL DGEBRD( M, N, A, LDA, S, WORK( IE ), WORK( ITAUQ ),
     $                   WORK( ITAUP ), WORK( IWORK ), LWORK-IWORK+1,
     $                   IERR )
            IF( WNTUAS ) THEN
*
*              If left singular vectors desired in U, copy result to U
*              and generate left bidiagonalizing vectors in U
*              (Workspace: need 3*N + NCU, prefer 3*N + NCU*NB)
*
               CALL DLACPY( 'L', M, N, A, LDA, U, LDU )
               IF( WNTUS )
     $            NCU = N
               IF( WNTUA )
     $            NCU = M
               CALL DORGBR( 'Q', M, NCU, N, U, LDU, WORK( ITAUQ ),
     $                      WORK( IWORK ), LWORK-IWORK+1, IERR )
            END IF
            IF( WNTVAS ) THEN
*
*              If right singular vectors desired in VT, copy result to
*              VT and generate right bidiagonalizing vectors in VT
*              (Workspace: need 4*N-1, prefer 3*N + (N-1)*NB)
*
               CALL DLACPY( 'U', N, N, A, LDA, VT, LDVT )
               CALL DORGBR( 'P', N, N, N, VT, LDVT, WORK( ITAUP ),
     $                      WORK( IWORK ), LWORK-IWORK+1, IERR )
            END IF
            IF( WNTUO ) THEN
*
*              If left singular vectors desired in A, generate left
*              bidiagonalizing vectors in A
*              (Workspace: need 4*N, prefer 3*N + N*NB)
*
               CALL DORGBR( 'Q', M, N, N, A, LDA, WORK( ITAUQ ),
     $                      WORK( IWORK ), LWORK-IWORK+1, IERR )
            END IF
            IF( WNTVO ) THEN
*
*              If right singular vectors desired in A, generate right
*              bidiagonalizing vectors in A
*              (Workspace: need 4*N-1, prefer 3*N + (N-1)*NB)
*
               CALL DORGBR( 'P', N, N, N, A, LDA, WORK( ITAUP ),
     $                      WORK( IWORK ), LWORK-IWORK+1, IERR )
            END IF
            IWORK = IE + N
            IF( WNTUAS .OR. WNTUO )
     $         NRU = M
            IF( WNTUN )
     $         NRU = 0
            IF( WNTVAS .OR. WNTVO )
     $         NCVT = N
            IF( WNTVN )
     $         NCVT = 0
            IF( ( .NOT.WNTUO ) .AND. ( .NOT.WNTVO ) ) THEN
*
*              Perform bidiagonal QR iteration, if desired, computing
*              left singular vectors in U and computing right singular
*              vectors in VT
*              (Workspace: need BDSPAC)
*
               CALL DBDSQR( 'U', N, NCVT, NRU, 0, S, WORK( IE ), VT,
     $                      LDVT, U, LDU, DUM, 1, WORK( IWORK ), INFO )
            ELSE IF( ( .NOT.WNTUO ) .AND. WNTVO ) THEN
*
*              Perform bidiagonal QR iteration, if desired, computing
*              left singular vectors in U and computing right singular
*              vectors in A
*              (Workspace: need BDSPAC)
*
               CALL DBDSQR( 'U', N, NCVT, NRU, 0, S, WORK( IE ), A, LDA,
     $                      U, LDU, DUM, 1, WORK( IWORK ), INFO )
            ELSE
*
*              Perform bidiagonal QR iteration, if desired, computing
*              left singular vectors in A and computing right singular
*              vectors in VT
*              (Workspace: need BDSPAC)
*
               CALL DBDSQR( 'U', N, NCVT, NRU, 0, S, WORK( IE ), VT,
     $                      LDVT, A, LDA, DUM, 1, WORK( IWORK ), INFO )
            END IF
*
         END IF
*
      ELSE
*
*        A has more columns than rows. If A has sufficiently more
*        columns than rows, first reduce using the LQ decomposition (if
*        sufficient workspace available)
*
         IF( N.GE.MNTHR ) THEN
*
            IF( WNTVN ) THEN
*
*              Path 1t(N much larger than M, JOBVT='N')
*              No right singular vectors to be computed
*
               ITAU = 1
               IWORK = ITAU + M
*
*              Compute A=L*Q
*              (Workspace: need 2*M, prefer M + M*NB)
*
               CALL DGELQF( M, N, A, LDA, WORK( ITAU ), WORK( IWORK ),
     $                      LWORK-IWORK+1, IERR )
*
*              Zero out above L
*
               CALL DLASET( 'U', M-1, M-1, ZERO, ZERO, A( 1, 2 ), LDA )
               IE = 1
               ITAUQ = IE + M
               ITAUP = ITAUQ + M
               IWORK = ITAUP + M
*
*              Bidiagonalize L in A
*              (Workspace: need 4*M, prefer 3*M + 2*M*NB)
*
               CALL DGEBRD( M, M, A, LDA, S, WORK( IE ), WORK( ITAUQ ),
     $                      WORK( ITAUP ), WORK( IWORK ), LWORK-IWORK+1,
     $                      IERR )
               IF( WNTUO .OR. WNTUAS ) THEN
*
*                 If left singular vectors desired, generate Q
*                 (Workspace: need 4*M, prefer 3*M + M*NB)
*
                  CALL DORGBR( 'Q', M, M, M, A, LDA, WORK( ITAUQ ),
     $                         WORK( IWORK ), LWORK-IWORK+1, IERR )
               END IF
               IWORK = IE + M
               NRU = 0
               IF( WNTUO .OR. WNTUAS )
     $            NRU = M
*
*              Perform bidiagonal QR iteration, computing left singular
*              vectors of A in A if desired
*              (Workspace: need BDSPAC)
*
               CALL DBDSQR( 'U', M, 0, NRU, 0, S, WORK( IE ), DUM, 1, A,
     $                      LDA, DUM, 1, WORK( IWORK ), INFO )
*
*              If left singular vectors desired in U, copy them there
*
               IF( WNTUAS )
     $            CALL DLACPY( 'F', M, M, A, LDA, U, LDU )
*
            ELSE IF( WNTVO .AND. WNTUN ) THEN
*
*              Path 2t(N much larger than M, JOBU='N', JOBVT='O')
*              M right singular vectors to be overwritten on A and
*              no left singular vectors to be computed
*
               IF( LWORK.GE.M*M+MAX( 4*M, BDSPAC ) ) THEN
*
*                 Sufficient workspace for a fast algorithm
*
                  IR = 1
                  IF( LWORK.GE.MAX( WRKBL, LDA*N + M ) + LDA*M ) THEN
*
*                    WORK(IU) is LDA by N and WORK(IR) is LDA by M
*
                     LDWRKU = LDA
                     CHUNK = N
                     LDWRKR = LDA
                  ELSE IF( LWORK.GE.MAX( WRKBL, LDA*N + M ) + M*M ) THEN
*
*                    WORK(IU) is LDA by N and WORK(IR) is M by M
*
                     LDWRKU = LDA
                     CHUNK = N
                     LDWRKR = M
                  ELSE
*
*                    WORK(IU) is M by CHUNK and WORK(IR) is M by M
*
                     LDWRKU = M
                     CHUNK = ( LWORK-M*M-M ) / M
                     LDWRKR = M
                  END IF
                  ITAU = IR + LDWRKR*M
                  IWORK = ITAU + M
*
*                 Compute A=L*Q
*                 (Workspace: need M*M + 2*M, prefer M*M + M + M*NB)
*
                  CALL DGELQF( M, N, A, LDA, WORK( ITAU ),
     $                         WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                 Copy L to WORK(IR) and zero out above it
*
                  CALL DLACPY( 'L', M, M, A, LDA, WORK( IR ), LDWRKR )
                  CALL DLASET( 'U', M-1, M-1, ZERO, ZERO,
     $                         WORK( IR+LDWRKR ), LDWRKR )
*
*                 Generate Q in A
*                 (Workspace: need M*M + 2*M, prefer M*M + M + M*NB)
*
                  CALL DORGLQ( M, N, M, A, LDA, WORK( ITAU ),
     $                         WORK( IWORK ), LWORK-IWORK+1, IERR )
                  IE = ITAU
                  ITAUQ = IE + M
                  ITAUP = ITAUQ + M
                  IWORK = ITAUP + M
*
*                 Bidiagonalize L in WORK(IR)
*                 (Workspace: need M*M + 4*M, prefer M*M + 3*M + 2*M*NB)
*
                  CALL DGEBRD( M, M, WORK( IR ), LDWRKR, S, WORK( IE ),
     $                         WORK( ITAUQ ), WORK( ITAUP ),
     $                         WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                 Generate right vectors bidiagonalizing L
*                 (Workspace: need M*M + 4*M-1, prefer M*M + 3*M + (M-1)*NB)
*
                  CALL DORGBR( 'P', M, M, M, WORK( IR ), LDWRKR,
     $                         WORK( ITAUP ), WORK( IWORK ),
     $                         LWORK-IWORK+1, IERR )
                  IWORK = IE + M
*
*                 Perform bidiagonal QR iteration, computing right
*                 singular vectors of L in WORK(IR)
*                 (Workspace: need M*M + BDSPAC)
*
                  CALL DBDSQR( 'U', M, M, 0, 0, S, WORK( IE ),
     $                         WORK( IR ), LDWRKR, DUM, 1, DUM, 1,
     $                         WORK( IWORK ), INFO )
                  IU = IE + M
*
*                 Multiply right singular vectors of L in WORK(IR) by Q
*                 in A, storing result in WORK(IU) and copying to A
*                 (Workspace: need M*M + 2*M, prefer M*M + M*N + M)
*
                  DO 30 I = 1, N, CHUNK
                     BLK = MIN( N-I+1, CHUNK )
                     CALL DGEMM( 'N', 'N', M, BLK, M, ONE, WORK( IR ),
     $                           LDWRKR, A( 1, I ), LDA, ZERO,
     $                           WORK( IU ), LDWRKU )
                     CALL DLACPY( 'F', M, BLK, WORK( IU ), LDWRKU,
     $                            A( 1, I ), LDA )
   30             CONTINUE
*
               ELSE
*
*                 Insufficient workspace for a fast algorithm
*
                  IE = 1
                  ITAUQ = IE + M
                  ITAUP = ITAUQ + M
                  IWORK = ITAUP + M
*
*                 Bidiagonalize A
*                 (Workspace: need 3*M + N, prefer 3*M + (M + N)*NB)
*
                  CALL DGEBRD( M, N, A, LDA, S, WORK( IE ),
     $                         WORK( ITAUQ ), WORK( ITAUP ),
     $                         WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                 Generate right vectors bidiagonalizing A
*                 (Workspace: need 4*M, prefer 3*M + M*NB)
*
                  CALL DORGBR( 'P', M, N, M, A, LDA, WORK( ITAUP ),
     $                         WORK( IWORK ), LWORK-IWORK+1, IERR )
                  IWORK = IE + M
*
*                 Perform bidiagonal QR iteration, computing right
*                 singular vectors of A in A
*                 (Workspace: need BDSPAC)
*
                  CALL DBDSQR( 'L', M, N, 0, 0, S, WORK( IE ), A, LDA,
     $                         DUM, 1, DUM, 1, WORK( IWORK ), INFO )
*
               END IF
*
            ELSE IF( WNTVO .AND. WNTUAS ) THEN
*
*              Path 3t(N much larger than M, JOBU='S' or 'A', JOBVT='O')
*              M right singular vectors to be overwritten on A and
*              M left singular vectors to be computed in U
*
               IF( LWORK.GE.M*M+MAX( 4*M, BDSPAC ) ) THEN
*
*                 Sufficient workspace for a fast algorithm
*
                  IR = 1
                  IF( LWORK.GE.MAX( WRKBL, LDA*N + M ) + LDA*M ) THEN
*
*                    WORK(IU) is LDA by N and WORK(IR) is LDA by M
*
                     LDWRKU = LDA
                     CHUNK = N
                     LDWRKR = LDA
                  ELSE IF( LWORK.GE.MAX( WRKBL, LDA*N + M ) + M*M ) THEN
*
*                    WORK(IU) is LDA by N and WORK(IR) is M by M
*
                     LDWRKU = LDA
                     CHUNK = N
                     LDWRKR = M
                  ELSE
*
*                    WORK(IU) is M by CHUNK and WORK(IR) is M by M
*
                     LDWRKU = M
                     CHUNK = ( LWORK-M*M-M ) / M
                     LDWRKR = M
                  END IF
                  ITAU = IR + LDWRKR*M
                  IWORK = ITAU + M
*
*                 Compute A=L*Q
*                 (Workspace: need M*M + 2*M, prefer M*M + M + M*NB)
*
                  CALL DGELQF( M, N, A, LDA, WORK( ITAU ),
     $                         WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                 Copy L to U, zeroing about above it
*
                  CALL DLACPY( 'L', M, M, A, LDA, U, LDU )
                  CALL DLASET( 'U', M-1, M-1, ZERO, ZERO, U( 1, 2 ),
     $                         LDU )
*
*                 Generate Q in A
*                 (Workspace: need M*M + 2*M, prefer M*M + M + M*NB)
*
                  CALL DORGLQ( M, N, M, A, LDA, WORK( ITAU ),
     $                         WORK( IWORK ), LWORK-IWORK+1, IERR )
                  IE = ITAU
                  ITAUQ = IE + M
                  ITAUP = ITAUQ + M
                  IWORK = ITAUP + M
*
*                 Bidiagonalize L in U, copying result to WORK(IR)
*                 (Workspace: need M*M + 4*M, prefer M*M + 3*M + 2*M*NB)
*
                  CALL DGEBRD( M, M, U, LDU, S, WORK( IE ),
     $                         WORK( ITAUQ ), WORK( ITAUP ),
     $                         WORK( IWORK ), LWORK-IWORK+1, IERR )
                  CALL DLACPY( 'U', M, M, U, LDU, WORK( IR ), LDWRKR )
*
*                 Generate right vectors bidiagonalizing L in WORK(IR)
*                 (Workspace: need M*M + 4*M-1, prefer M*M + 3*M + (M-1)*NB)
*
                  CALL DORGBR( 'P', M, M, M, WORK( IR ), LDWRKR,
     $                         WORK( ITAUP ), WORK( IWORK ),
     $                         LWORK-IWORK+1, IERR )
*
*                 Generate left vectors bidiagonalizing L in U
*                 (Workspace: need M*M + 4*M, prefer M*M + 3*M + M*NB)
*
                  CALL DORGBR( 'Q', M, M, M, U, LDU, WORK( ITAUQ ),
     $                         WORK( IWORK ), LWORK-IWORK+1, IERR )
                  IWORK = IE + M
*
*                 Perform bidiagonal QR iteration, computing left
*                 singular vectors of L in U, and computing right
*                 singular vectors of L in WORK(IR)
*                 (Workspace: need M*M + BDSPAC)
*
                  CALL DBDSQR( 'U', M, M, M, 0, S, WORK( IE ),
     $                         WORK( IR ), LDWRKR, U, LDU, DUM, 1,
     $                         WORK( IWORK ), INFO )
                  IU = IE + M
*
*                 Multiply right singular vectors of L in WORK(IR) by Q
*                 in A, storing result in WORK(IU) and copying to A
*                 (Workspace: need M*M + 2*M, prefer M*M + M*N + M))
*
                  DO 40 I = 1, N, CHUNK
                     BLK = MIN( N-I+1, CHUNK )
                     CALL DGEMM( 'N', 'N', M, BLK, M, ONE, WORK( IR ),
     $                           LDWRKR, A( 1, I ), LDA, ZERO,
     $                           WORK( IU ), LDWRKU )
                     CALL DLACPY( 'F', M, BLK, WORK( IU ), LDWRKU,
     $                            A( 1, I ), LDA )
   40             CONTINUE
*
               ELSE
*
*                 Insufficient workspace for a fast algorithm
*
                  ITAU = 1
                  IWORK = ITAU + M
*
*                 Compute A=L*Q
*                 (Workspace: need 2*M, prefer M + M*NB)
*
                  CALL DGELQF( M, N, A, LDA, WORK( ITAU ),
     $                         WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                 Copy L to U, zeroing out above it
*
                  CALL DLACPY( 'L', M, M, A, LDA, U, LDU )
                  CALL DLASET( 'U', M-1, M-1, ZERO, ZERO, U( 1, 2 ),
     $                         LDU )
*
*                 Generate Q in A
*                 (Workspace: need 2*M, prefer M + M*NB)
*
                  CALL DORGLQ( M, N, M, A, LDA, WORK( ITAU ),
     $                         WORK( IWORK ), LWORK-IWORK+1, IERR )
                  IE = ITAU
                  ITAUQ = IE + M
                  ITAUP = ITAUQ + M
                  IWORK = ITAUP + M
*
*                 Bidiagonalize L in U
*                 (Workspace: need 4*M, prefer 3*M + 2*M*NB)
*
                  CALL DGEBRD( M, M, U, LDU, S, WORK( IE ),
     $                         WORK( ITAUQ ), WORK( ITAUP ),
     $                         WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                 Multiply right vectors bidiagonalizing L by Q in A
*                 (Workspace: need 3*M + N, prefer 3*M + N*NB)
*
                  CALL DORMBR( 'P', 'L', 'T', M, N, M, U, LDU,
     $                         WORK( ITAUP ), A, LDA, WORK( IWORK ),
     $                         LWORK-IWORK+1, IERR )
*
*                 Generate left vectors bidiagonalizing L in U
*                 (Workspace: need 4*M, prefer 3*M + M*NB)
*
                  CALL DORGBR( 'Q', M, M, M, U, LDU, WORK( ITAUQ ),
     $                         WORK( IWORK ), LWORK-IWORK+1, IERR )
                  IWORK = IE + M
*
*                 Perform bidiagonal QR iteration, computing left
*                 singular vectors of A in U and computing right
*                 singular vectors of A in A
*                 (Workspace: need BDSPAC)
*
                  CALL DBDSQR( 'U', M, N, M, 0, S, WORK( IE ), A, LDA,
     $                         U, LDU, DUM, 1, WORK( IWORK ), INFO )
*
               END IF
*
            ELSE IF( WNTVS ) THEN
*
               IF( WNTUN ) THEN
*
*                 Path 4t(N much larger than M, JOBU='N', JOBVT='S')
*                 M right singular vectors to be computed in VT and
*                 no left singular vectors to be computed
*
                  IF( LWORK.GE.M*M+MAX( 4*M, BDSPAC ) ) THEN
*
*                    Sufficient workspace for a fast algorithm
*
                     IR = 1
                     IF( LWORK.GE.WRKBL+LDA*M ) THEN
*
*                       WORK(IR) is LDA by M
*
                        LDWRKR = LDA
                     ELSE
*
*                       WORK(IR) is M by M
*
                        LDWRKR = M
                     END IF
                     ITAU = IR + LDWRKR*M
                     IWORK = ITAU + M
*
*                    Compute A=L*Q
*                    (Workspace: need M*M + 2*M, prefer M*M + M + M*NB)
*
                     CALL DGELQF( M, N, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Copy L to WORK(IR), zeroing out above it
*
                     CALL DLACPY( 'L', M, M, A, LDA, WORK( IR ),
     $                            LDWRKR )
                     CALL DLASET( 'U', M-1, M-1, ZERO, ZERO,
     $                            WORK( IR+LDWRKR ), LDWRKR )
*
*                    Generate Q in A
*                    (Workspace: need M*M + 2*M, prefer M*M + M + M*NB)
*
                     CALL DORGLQ( M, N, M, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IE = ITAU
                     ITAUQ = IE + M
                     ITAUP = ITAUQ + M
                     IWORK = ITAUP + M
*
*                    Bidiagonalize L in WORK(IR)
*                    (Workspace: need M*M + 4*M, prefer M*M + 3*M + 2*M*NB)
*
                     CALL DGEBRD( M, M, WORK( IR ), LDWRKR, S,
     $                            WORK( IE ), WORK( ITAUQ ),
     $                            WORK( ITAUP ), WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
*
*                    Generate right vectors bidiagonalizing L in
*                    WORK(IR)
*                    (Workspace: need M*M + 4*M, prefer M*M + 3*M + (M-1)*NB)
*
                     CALL DORGBR( 'P', M, M, M, WORK( IR ), LDWRKR,
     $                            WORK( ITAUP ), WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
                     IWORK = IE + M
*
*                    Perform bidiagonal QR iteration, computing right
*                    singular vectors of L in WORK(IR)
*                    (Workspace: need M*M + BDSPAC)
*
                     CALL DBDSQR( 'U', M, M, 0, 0, S, WORK( IE ),
     $                            WORK( IR ), LDWRKR, DUM, 1, DUM, 1,
     $                            WORK( IWORK ), INFO )
*
*                    Multiply right singular vectors of L in WORK(IR) by
*                    Q in A, storing result in VT
*                    (Workspace: need M*M)
*
                     CALL DGEMM( 'N', 'N', M, N, M, ONE, WORK( IR ),
     $                           LDWRKR, A, LDA, ZERO, VT, LDVT )
*
                  ELSE
*
*                    Insufficient workspace for a fast algorithm
*
                     ITAU = 1
                     IWORK = ITAU + M
*
*                    Compute A=L*Q
*                    (Workspace: need 2*M, prefer M + M*NB)
*
                     CALL DGELQF( M, N, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Copy result to VT
*
                     CALL DLACPY( 'U', M, N, A, LDA, VT, LDVT )
*
*                    Generate Q in VT
*                    (Workspace: need 2*M, prefer M + M*NB)
*
                     CALL DORGLQ( M, N, M, VT, LDVT, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IE = ITAU
                     ITAUQ = IE + M
                     ITAUP = ITAUQ + M
                     IWORK = ITAUP + M
*
*                    Zero out above L in A
*
                     CALL DLASET( 'U', M-1, M-1, ZERO, ZERO, A( 1, 2 ),
     $                            LDA )
*
*                    Bidiagonalize L in A
*                    (Workspace: need 4*M, prefer 3*M + 2*M*NB)
*
                     CALL DGEBRD( M, M, A, LDA, S, WORK( IE ),
     $                            WORK( ITAUQ ), WORK( ITAUP ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Multiply right vectors bidiagonalizing L by Q in VT
*                    (Workspace: need 3*M + N, prefer 3*M + N*NB)
*
                     CALL DORMBR( 'P', 'L', 'T', M, N, M, A, LDA,
     $                            WORK( ITAUP ), VT, LDVT,
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IWORK = IE + M
*
*                    Perform bidiagonal QR iteration, computing right
*                    singular vectors of A in VT
*                    (Workspace: need BDSPAC)
*
                     CALL DBDSQR( 'U', M, N, 0, 0, S, WORK( IE ), VT,
     $                            LDVT, DUM, 1, DUM, 1, WORK( IWORK ),
     $                            INFO )
*
                  END IF
*
               ELSE IF( WNTUO ) THEN
*
*                 Path 5t(N much larger than M, JOBU='O', JOBVT='S')
*                 M right singular vectors to be computed in VT and
*                 M left singular vectors to be overwritten on A
*
                  IF( LWORK.GE.2*M*M+MAX( 4*M, BDSPAC ) ) THEN
*
*                    Sufficient workspace for a fast algorithm
*
                     IU = 1
                     IF( LWORK.GE.WRKBL+2*LDA*M ) THEN
*
*                       WORK(IU) is LDA by M and WORK(IR) is LDA by M
*
                        LDWRKU = LDA
                        IR = IU + LDWRKU*M
                        LDWRKR = LDA
                     ELSE IF( LWORK.GE.WRKBL+( LDA + M )*M ) THEN
*
*                       WORK(IU) is LDA by M and WORK(IR) is M by M
*
                        LDWRKU = LDA
                        IR = IU + LDWRKU*M
                        LDWRKR = M
                     ELSE
*
*                       WORK(IU) is M by M and WORK(IR) is M by M
*
                        LDWRKU = M
                        IR = IU + LDWRKU*M
                        LDWRKR = M
                     END IF
                     ITAU = IR + LDWRKR*M
                     IWORK = ITAU + M
*
*                    Compute A=L*Q
*                    (Workspace: need 2*M*M + 2*M, prefer 2*M*M + M + M*NB)
*
                     CALL DGELQF( M, N, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Copy L to WORK(IU), zeroing out below it
*
                     CALL DLACPY( 'L', M, M, A, LDA, WORK( IU ),
     $                            LDWRKU )
                     CALL DLASET( 'U', M-1, M-1, ZERO, ZERO,
     $                            WORK( IU+LDWRKU ), LDWRKU )
*
*                    Generate Q in A
*                    (Workspace: need 2*M*M + 2*M, prefer 2*M*M + M + M*NB)
*
                     CALL DORGLQ( M, N, M, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IE = ITAU
                     ITAUQ = IE + M
                     ITAUP = ITAUQ + M
                     IWORK = ITAUP + M
*
*                    Bidiagonalize L in WORK(IU), copying result to
*                    WORK(IR)
*                    (Workspace: need 2*M*M + 4*M,
*                                prefer 2*M*M+3*M+2*M*NB)
*
                     CALL DGEBRD( M, M, WORK( IU ), LDWRKU, S,
     $                            WORK( IE ), WORK( ITAUQ ),
     $                            WORK( ITAUP ), WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
                     CALL DLACPY( 'L', M, M, WORK( IU ), LDWRKU,
     $                            WORK( IR ), LDWRKR )
*
*                    Generate right bidiagonalizing vectors in WORK(IU)
*                    (Workspace: need 2*M*M + 4*M-1,
*                                prefer 2*M*M+3*M+(M-1)*NB)
*
                     CALL DORGBR( 'P', M, M, M, WORK( IU ), LDWRKU,
     $                            WORK( ITAUP ), WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
*
*                    Generate left bidiagonalizing vectors in WORK(IR)
*                    (Workspace: need 2*M*M + 4*M, prefer 2*M*M + 3*M + M*NB)
*
                     CALL DORGBR( 'Q', M, M, M, WORK( IR ), LDWRKR,
     $                            WORK( ITAUQ ), WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
                     IWORK = IE + M
*
*                    Perform bidiagonal QR iteration, computing left
*                    singular vectors of L in WORK(IR) and computing
*                    right singular vectors of L in WORK(IU)
*                    (Workspace: need 2*M*M + BDSPAC)
*
                     CALL DBDSQR( 'U', M, M, M, 0, S, WORK( IE ),
     $                            WORK( IU ), LDWRKU, WORK( IR ),
     $                            LDWRKR, DUM, 1, WORK( IWORK ), INFO )
*
*                    Multiply right singular vectors of L in WORK(IU) by
*                    Q in A, storing result in VT
*                    (Workspace: need M*M)
*
                     CALL DGEMM( 'N', 'N', M, N, M, ONE, WORK( IU ),
     $                           LDWRKU, A, LDA, ZERO, VT, LDVT )
*
*                    Copy left singular vectors of L to A
*                    (Workspace: need M*M)
*
                     CALL DLACPY( 'F', M, M, WORK( IR ), LDWRKR, A,
     $                            LDA )
*
                  ELSE
*
*                    Insufficient workspace for a fast algorithm
*
                     ITAU = 1
                     IWORK = ITAU + M
*
*                    Compute A=L*Q, copying result to VT
*                    (Workspace: need 2*M, prefer M + M*NB)
*
                     CALL DGELQF( M, N, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     CALL DLACPY( 'U', M, N, A, LDA, VT, LDVT )
*
*                    Generate Q in VT
*                    (Workspace: need 2*M, prefer M + M*NB)
*
                     CALL DORGLQ( M, N, M, VT, LDVT, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IE = ITAU
                     ITAUQ = IE + M
                     ITAUP = ITAUQ + M
                     IWORK = ITAUP + M
*
*                    Zero out above L in A
*
                     CALL DLASET( 'U', M-1, M-1, ZERO, ZERO, A( 1, 2 ),
     $                            LDA )
*
*                    Bidiagonalize L in A
*                    (Workspace: need 4*M, prefer 3*M + 2*M*NB)
*
                     CALL DGEBRD( M, M, A, LDA, S, WORK( IE ),
     $                            WORK( ITAUQ ), WORK( ITAUP ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Multiply right vectors bidiagonalizing L by Q in VT
*                    (Workspace: need 3*M + N, prefer 3*M + N*NB)
*
                     CALL DORMBR( 'P', 'L', 'T', M, N, M, A, LDA,
     $                            WORK( ITAUP ), VT, LDVT,
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Generate left bidiagonalizing vectors of L in A
*                    (Workspace: need 4*M, prefer 3*M + M*NB)
*
                     CALL DORGBR( 'Q', M, M, M, A, LDA, WORK( ITAUQ ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IWORK = IE + M
*
*                    Perform bidiagonal QR iteration, compute left
*                    singular vectors of A in A and compute right
*                    singular vectors of A in VT
*                    (Workspace: need BDSPAC)
*
                     CALL DBDSQR( 'U', M, N, M, 0, S, WORK( IE ), VT,
     $                            LDVT, A, LDA, DUM, 1, WORK( IWORK ),
     $                            INFO )
*
                  END IF
*
               ELSE IF( WNTUAS ) THEN
*
*                 Path 6t(N much larger than M, JOBU='S' or 'A',
*                         JOBVT='S')
*                 M right singular vectors to be computed in VT and
*                 M left singular vectors to be computed in U
*
                  IF( LWORK.GE.M*M+MAX( 4*M, BDSPAC ) ) THEN
*
*                    Sufficient workspace for a fast algorithm
*
                     IU = 1
                     IF( LWORK.GE.WRKBL+LDA*M ) THEN
*
*                       WORK(IU) is LDA by N
*
                        LDWRKU = LDA
                     ELSE
*
*                       WORK(IU) is LDA by M
*
                        LDWRKU = M
                     END IF
                     ITAU = IU + LDWRKU*M
                     IWORK = ITAU + M
*
*                    Compute A=L*Q
*                    (Workspace: need M*M + 2*M, prefer M*M + M + M*NB)
*
                     CALL DGELQF( M, N, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Copy L to WORK(IU), zeroing out above it
*
                     CALL DLACPY( 'L', M, M, A, LDA, WORK( IU ),
     $                            LDWRKU )
                     CALL DLASET( 'U', M-1, M-1, ZERO, ZERO,
     $                            WORK( IU+LDWRKU ), LDWRKU )
*
*                    Generate Q in A
*                    (Workspace: need M*M + 2*M, prefer M*M + M + M*NB)
*
                     CALL DORGLQ( M, N, M, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IE = ITAU
                     ITAUQ = IE + M
                     ITAUP = ITAUQ + M
                     IWORK = ITAUP + M
*
*                    Bidiagonalize L in WORK(IU), copying result to U
*                    (Workspace: need M*M + 4*M, prefer M*M + 3*M + 2*M*NB)
*
                     CALL DGEBRD( M, M, WORK( IU ), LDWRKU, S,
     $                            WORK( IE ), WORK( ITAUQ ),
     $                            WORK( ITAUP ), WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
                     CALL DLACPY( 'L', M, M, WORK( IU ), LDWRKU, U,
     $                            LDU )
*
*                    Generate right bidiagonalizing vectors in WORK(IU)
*                    (Workspace: need M*M + 4*M-1,
*                                prefer M*M+3*M+(M-1)*NB)
*
                     CALL DORGBR( 'P', M, M, M, WORK( IU ), LDWRKU,
     $                            WORK( ITAUP ), WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
*
*                    Generate left bidiagonalizing vectors in U
*                    (Workspace: need M*M + 4*M, prefer M*M + 3*M + M*NB)
*
                     CALL DORGBR( 'Q', M, M, M, U, LDU, WORK( ITAUQ ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IWORK = IE + M
*
*                    Perform bidiagonal QR iteration, computing left
*                    singular vectors of L in U and computing right
*                    singular vectors of L in WORK(IU)
*                    (Workspace: need M*M + BDSPAC)
*
                     CALL DBDSQR( 'U', M, M, M, 0, S, WORK( IE ),
     $                            WORK( IU ), LDWRKU, U, LDU, DUM, 1,
     $                            WORK( IWORK ), INFO )
*
*                    Multiply right singular vectors of L in WORK(IU) by
*                    Q in A, storing result in VT
*                    (Workspace: need M*M)
*
                     CALL DGEMM( 'N', 'N', M, N, M, ONE, WORK( IU ),
     $                           LDWRKU, A, LDA, ZERO, VT, LDVT )
*
                  ELSE
*
*                    Insufficient workspace for a fast algorithm
*
                     ITAU = 1
                     IWORK = ITAU + M
*
*                    Compute A=L*Q, copying result to VT
*                    (Workspace: need 2*M, prefer M + M*NB)
*
                     CALL DGELQF( M, N, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     CALL DLACPY( 'U', M, N, A, LDA, VT, LDVT )
*
*                    Generate Q in VT
*                    (Workspace: need 2*M, prefer M + M*NB)
*
                     CALL DORGLQ( M, N, M, VT, LDVT, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Copy L to U, zeroing out above it
*
                     CALL DLACPY( 'L', M, M, A, LDA, U, LDU )
                     CALL DLASET( 'U', M-1, M-1, ZERO, ZERO, U( 1, 2 ),
     $                            LDU )
                     IE = ITAU
                     ITAUQ = IE + M
                     ITAUP = ITAUQ + M
                     IWORK = ITAUP + M
*
*                    Bidiagonalize L in U
*                    (Workspace: need 4*M, prefer 3*M + 2*M*NB)
*
                     CALL DGEBRD( M, M, U, LDU, S, WORK( IE ),
     $                            WORK( ITAUQ ), WORK( ITAUP ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Multiply right bidiagonalizing vectors in U by Q
*                    in VT
*                    (Workspace: need 3*M + N, prefer 3*M + N*NB)
*
                     CALL DORMBR( 'P', 'L', 'T', M, N, M, U, LDU,
     $                            WORK( ITAUP ), VT, LDVT,
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Generate left bidiagonalizing vectors in U
*                    (Workspace: need 4*M, prefer 3*M + M*NB)
*
                     CALL DORGBR( 'Q', M, M, M, U, LDU, WORK( ITAUQ ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IWORK = IE + M
*
*                    Perform bidiagonal QR iteration, computing left
*                    singular vectors of A in U and computing right
*                    singular vectors of A in VT
*                    (Workspace: need BDSPAC)
*
                     CALL DBDSQR( 'U', M, N, M, 0, S, WORK( IE ), VT,
     $                            LDVT, U, LDU, DUM, 1, WORK( IWORK ),
     $                            INFO )
*
                  END IF
*
               END IF
*
            ELSE IF( WNTVA ) THEN
*
               IF( WNTUN ) THEN
*
*                 Path 7t(N much larger than M, JOBU='N', JOBVT='A')
*                 N right singular vectors to be computed in VT and
*                 no left singular vectors to be computed
*
                  IF( LWORK.GE.M*M+MAX( N + M, 4*M, BDSPAC ) ) THEN
*
*                    Sufficient workspace for a fast algorithm
*
                     IR = 1
                     IF( LWORK.GE.WRKBL+LDA*M ) THEN
*
*                       WORK(IR) is LDA by M
*
                        LDWRKR = LDA
                     ELSE
*
*                       WORK(IR) is M by M
*
                        LDWRKR = M
                     END IF
                     ITAU = IR + LDWRKR*M
                     IWORK = ITAU + M
*
*                    Compute A=L*Q, copying result to VT
*                    (Workspace: need M*M + 2*M, prefer M*M + M + M*NB)
*
                     CALL DGELQF( M, N, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     CALL DLACPY( 'U', M, N, A, LDA, VT, LDVT )
*
*                    Copy L to WORK(IR), zeroing out above it
*
                     CALL DLACPY( 'L', M, M, A, LDA, WORK( IR ),
     $                            LDWRKR )
                     CALL DLASET( 'U', M-1, M-1, ZERO, ZERO,
     $                            WORK( IR+LDWRKR ), LDWRKR )
*
*                    Generate Q in VT
*                    (Workspace: need M*M + M + N, prefer M*M + M + N*NB)
*
                     CALL DORGLQ( N, N, M, VT, LDVT, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IE = ITAU
                     ITAUQ = IE + M
                     ITAUP = ITAUQ + M
                     IWORK = ITAUP + M
*
*                    Bidiagonalize L in WORK(IR)
*                    (Workspace: need M*M + 4*M, prefer M*M + 3*M + 2*M*NB)
*
                     CALL DGEBRD( M, M, WORK( IR ), LDWRKR, S,
     $                            WORK( IE ), WORK( ITAUQ ),
     $                            WORK( ITAUP ), WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
*
*                    Generate right bidiagonalizing vectors in WORK(IR)
*                    (Workspace: need M*M + 4*M-1,
*                                prefer M*M+3*M+(M-1)*NB)
*
                     CALL DORGBR( 'P', M, M, M, WORK( IR ), LDWRKR,
     $                            WORK( ITAUP ), WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
                     IWORK = IE + M
*
*                    Perform bidiagonal QR iteration, computing right
*                    singular vectors of L in WORK(IR)
*                    (Workspace: need M*M + BDSPAC)
*
                     CALL DBDSQR( 'U', M, M, 0, 0, S, WORK( IE ),
     $                            WORK( IR ), LDWRKR, DUM, 1, DUM, 1,
     $                            WORK( IWORK ), INFO )
*
*                    Multiply right singular vectors of L in WORK(IR) by
*                    Q in VT, storing result in A
*                    (Workspace: need M*M)
*
                     CALL DGEMM( 'N', 'N', M, N, M, ONE, WORK( IR ),
     $                           LDWRKR, VT, LDVT, ZERO, A, LDA )
*
*                    Copy right singular vectors of A from A to VT
*
                     CALL DLACPY( 'F', M, N, A, LDA, VT, LDVT )
*
                  ELSE
*
*                    Insufficient workspace for a fast algorithm
*
                     ITAU = 1
                     IWORK = ITAU + M
*
*                    Compute A=L*Q, copying result to VT
*                    (Workspace: need 2*M, prefer M + M*NB)
*
                     CALL DGELQF( M, N, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     CALL DLACPY( 'U', M, N, A, LDA, VT, LDVT )
*
*                    Generate Q in VT
*                    (Workspace: need M + N, prefer M + N*NB)
*
                     CALL DORGLQ( N, N, M, VT, LDVT, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IE = ITAU
                     ITAUQ = IE + M
                     ITAUP = ITAUQ + M
                     IWORK = ITAUP + M
*
*                    Zero out above L in A
*
                     CALL DLASET( 'U', M-1, M-1, ZERO, ZERO, A( 1, 2 ),
     $                            LDA )
*
*                    Bidiagonalize L in A
*                    (Workspace: need 4*M, prefer 3*M + 2*M*NB)
*
                     CALL DGEBRD( M, M, A, LDA, S, WORK( IE ),
     $                            WORK( ITAUQ ), WORK( ITAUP ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Multiply right bidiagonalizing vectors in A by Q
*                    in VT
*                    (Workspace: need 3*M + N, prefer 3*M + N*NB)
*
                     CALL DORMBR( 'P', 'L', 'T', M, N, M, A, LDA,
     $                            WORK( ITAUP ), VT, LDVT,
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IWORK = IE + M
*
*                    Perform bidiagonal QR iteration, computing right
*                    singular vectors of A in VT
*                    (Workspace: need BDSPAC)
*
                     CALL DBDSQR( 'U', M, N, 0, 0, S, WORK( IE ), VT,
     $                            LDVT, DUM, 1, DUM, 1, WORK( IWORK ),
     $                            INFO )
*
                  END IF
*
               ELSE IF( WNTUO ) THEN
*
*                 Path 8t(N much larger than M, JOBU='O', JOBVT='A')
*                 N right singular vectors to be computed in VT and
*                 M left singular vectors to be overwritten on A
*
                  IF( LWORK.GE.2*M*M+MAX( N + M, 4*M, BDSPAC ) ) THEN
*
*                    Sufficient workspace for a fast algorithm
*
                     IU = 1
                     IF( LWORK.GE.WRKBL+2*LDA*M ) THEN
*
*                       WORK(IU) is LDA by M and WORK(IR) is LDA by M
*
                        LDWRKU = LDA
                        IR = IU + LDWRKU*M
                        LDWRKR = LDA
                     ELSE IF( LWORK.GE.WRKBL+( LDA + M )*M ) THEN
*
*                       WORK(IU) is LDA by M and WORK(IR) is M by M
*
                        LDWRKU = LDA
                        IR = IU + LDWRKU*M
                        LDWRKR = M
                     ELSE
*
*                       WORK(IU) is M by M and WORK(IR) is M by M
*
                        LDWRKU = M
                        IR = IU + LDWRKU*M
                        LDWRKR = M
                     END IF
                     ITAU = IR + LDWRKR*M
                     IWORK = ITAU + M
*
*                    Compute A=L*Q, copying result to VT
*                    (Workspace: need 2*M*M + 2*M, prefer 2*M*M + M + M*NB)
*
                     CALL DGELQF( M, N, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     CALL DLACPY( 'U', M, N, A, LDA, VT, LDVT )
*
*                    Generate Q in VT
*                    (Workspace: need 2*M*M + M + N, prefer 2*M*M + M + N*NB)
*
                     CALL DORGLQ( N, N, M, VT, LDVT, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Copy L to WORK(IU), zeroing out above it
*
                     CALL DLACPY( 'L', M, M, A, LDA, WORK( IU ),
     $                            LDWRKU )
                     CALL DLASET( 'U', M-1, M-1, ZERO, ZERO,
     $                            WORK( IU+LDWRKU ), LDWRKU )
                     IE = ITAU
                     ITAUQ = IE + M
                     ITAUP = ITAUQ + M
                     IWORK = ITAUP + M
*
*                    Bidiagonalize L in WORK(IU), copying result to
*                    WORK(IR)
*                    (Workspace: need 2*M*M + 4*M,
*                                prefer 2*M*M+3*M+2*M*NB)
*
                     CALL DGEBRD( M, M, WORK( IU ), LDWRKU, S,
     $                            WORK( IE ), WORK( ITAUQ ),
     $                            WORK( ITAUP ), WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
                     CALL DLACPY( 'L', M, M, WORK( IU ), LDWRKU,
     $                            WORK( IR ), LDWRKR )
*
*                    Generate right bidiagonalizing vectors in WORK(IU)
*                    (Workspace: need 2*M*M + 4*M-1,
*                                prefer 2*M*M+3*M+(M-1)*NB)
*
                     CALL DORGBR( 'P', M, M, M, WORK( IU ), LDWRKU,
     $                            WORK( ITAUP ), WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
*
*                    Generate left bidiagonalizing vectors in WORK(IR)
*                    (Workspace: need 2*M*M + 4*M, prefer 2*M*M + 3*M + M*NB)
*
                     CALL DORGBR( 'Q', M, M, M, WORK( IR ), LDWRKR,
     $                            WORK( ITAUQ ), WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
                     IWORK = IE + M
*
*                    Perform bidiagonal QR iteration, computing left
*                    singular vectors of L in WORK(IR) and computing
*                    right singular vectors of L in WORK(IU)
*                    (Workspace: need 2*M*M + BDSPAC)
*
                     CALL DBDSQR( 'U', M, M, M, 0, S, WORK( IE ),
     $                            WORK( IU ), LDWRKU, WORK( IR ),
     $                            LDWRKR, DUM, 1, WORK( IWORK ), INFO )
*
*                    Multiply right singular vectors of L in WORK(IU) by
*                    Q in VT, storing result in A
*                    (Workspace: need M*M)
*
                     CALL DGEMM( 'N', 'N', M, N, M, ONE, WORK( IU ),
     $                           LDWRKU, VT, LDVT, ZERO, A, LDA )
*
*                    Copy right singular vectors of A from A to VT
*
                     CALL DLACPY( 'F', M, N, A, LDA, VT, LDVT )
*
*                    Copy left singular vectors of A from WORK(IR) to A
*
                     CALL DLACPY( 'F', M, M, WORK( IR ), LDWRKR, A,
     $                            LDA )
*
                  ELSE
*
*                    Insufficient workspace for a fast algorithm
*
                     ITAU = 1
                     IWORK = ITAU + M
*
*                    Compute A=L*Q, copying result to VT
*                    (Workspace: need 2*M, prefer M + M*NB)
*
                     CALL DGELQF( M, N, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     CALL DLACPY( 'U', M, N, A, LDA, VT, LDVT )
*
*                    Generate Q in VT
*                    (Workspace: need M + N, prefer M + N*NB)
*
                     CALL DORGLQ( N, N, M, VT, LDVT, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IE = ITAU
                     ITAUQ = IE + M
                     ITAUP = ITAUQ + M
                     IWORK = ITAUP + M
*
*                    Zero out above L in A
*
                     CALL DLASET( 'U', M-1, M-1, ZERO, ZERO, A( 1, 2 ),
     $                            LDA )
*
*                    Bidiagonalize L in A
*                    (Workspace: need 4*M, prefer 3*M + 2*M*NB)
*
                     CALL DGEBRD( M, M, A, LDA, S, WORK( IE ),
     $                            WORK( ITAUQ ), WORK( ITAUP ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Multiply right bidiagonalizing vectors in A by Q
*                    in VT
*                    (Workspace: need 3*M + N, prefer 3*M + N*NB)
*
                     CALL DORMBR( 'P', 'L', 'T', M, N, M, A, LDA,
     $                            WORK( ITAUP ), VT, LDVT,
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Generate left bidiagonalizing vectors in A
*                    (Workspace: need 4*M, prefer 3*M + M*NB)
*
                     CALL DORGBR( 'Q', M, M, M, A, LDA, WORK( ITAUQ ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IWORK = IE + M
*
*                    Perform bidiagonal QR iteration, computing left
*                    singular vectors of A in A and computing right
*                    singular vectors of A in VT
*                    (Workspace: need BDSPAC)
*
                     CALL DBDSQR( 'U', M, N, M, 0, S, WORK( IE ), VT,
     $                            LDVT, A, LDA, DUM, 1, WORK( IWORK ),
     $                            INFO )
*
                  END IF
*
               ELSE IF( WNTUAS ) THEN
*
*                 Path 9t(N much larger than M, JOBU='S' or 'A',
*                         JOBVT='A')
*                 N right singular vectors to be computed in VT and
*                 M left singular vectors to be computed in U
*
                  IF( LWORK.GE.M*M+MAX( N + M, 4*M, BDSPAC ) ) THEN
*
*                    Sufficient workspace for a fast algorithm
*
                     IU = 1
                     IF( LWORK.GE.WRKBL+LDA*M ) THEN
*
*                       WORK(IU) is LDA by M
*
                        LDWRKU = LDA
                     ELSE
*
*                       WORK(IU) is M by M
*
                        LDWRKU = M
                     END IF
                     ITAU = IU + LDWRKU*M
                     IWORK = ITAU + M
*
*                    Compute A=L*Q, copying result to VT
*                    (Workspace: need M*M + 2*M, prefer M*M + M + M*NB)
*
                     CALL DGELQF( M, N, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     CALL DLACPY( 'U', M, N, A, LDA, VT, LDVT )
*
*                    Generate Q in VT
*                    (Workspace: need M*M + M + N, prefer M*M + M + N*NB)
*
                     CALL DORGLQ( N, N, M, VT, LDVT, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Copy L to WORK(IU), zeroing out above it
*
                     CALL DLACPY( 'L', M, M, A, LDA, WORK( IU ),
     $                            LDWRKU )
                     CALL DLASET( 'U', M-1, M-1, ZERO, ZERO,
     $                            WORK( IU+LDWRKU ), LDWRKU )
                     IE = ITAU
                     ITAUQ = IE + M
                     ITAUP = ITAUQ + M
                     IWORK = ITAUP + M
*
*                    Bidiagonalize L in WORK(IU), copying result to U
*                    (Workspace: need M*M + 4*M, prefer M*M + 3*M + 2*M*NB)
*
                     CALL DGEBRD( M, M, WORK( IU ), LDWRKU, S,
     $                            WORK( IE ), WORK( ITAUQ ),
     $                            WORK( ITAUP ), WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
                     CALL DLACPY( 'L', M, M, WORK( IU ), LDWRKU, U,
     $                            LDU )
*
*                    Generate right bidiagonalizing vectors in WORK(IU)
*                    (Workspace: need M*M + 4*M, prefer M*M + 3*M + (M-1)*NB)
*
                     CALL DORGBR( 'P', M, M, M, WORK( IU ), LDWRKU,
     $                            WORK( ITAUP ), WORK( IWORK ),
     $                            LWORK-IWORK+1, IERR )
*
*                    Generate left bidiagonalizing vectors in U
*                    (Workspace: need M*M + 4*M, prefer M*M + 3*M + M*NB)
*
                     CALL DORGBR( 'Q', M, M, M, U, LDU, WORK( ITAUQ ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IWORK = IE + M
*
*                    Perform bidiagonal QR iteration, computing left
*                    singular vectors of L in U and computing right
*                    singular vectors of L in WORK(IU)
*                    (Workspace: need M*M + BDSPAC)
*
                     CALL DBDSQR( 'U', M, M, M, 0, S, WORK( IE ),
     $                            WORK( IU ), LDWRKU, U, LDU, DUM, 1,
     $                            WORK( IWORK ), INFO )
*
*                    Multiply right singular vectors of L in WORK(IU) by
*                    Q in VT, storing result in A
*                    (Workspace: need M*M)
*
                     CALL DGEMM( 'N', 'N', M, N, M, ONE, WORK( IU ),
     $                           LDWRKU, VT, LDVT, ZERO, A, LDA )
*
*                    Copy right singular vectors of A from A to VT
*
                     CALL DLACPY( 'F', M, N, A, LDA, VT, LDVT )
*
                  ELSE
*
*                    Insufficient workspace for a fast algorithm
*
                     ITAU = 1
                     IWORK = ITAU + M
*
*                    Compute A=L*Q, copying result to VT
*                    (Workspace: need 2*M, prefer M + M*NB)
*
                     CALL DGELQF( M, N, A, LDA, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     CALL DLACPY( 'U', M, N, A, LDA, VT, LDVT )
*
*                    Generate Q in VT
*                    (Workspace: need M + N, prefer M + N*NB)
*
                     CALL DORGLQ( N, N, M, VT, LDVT, WORK( ITAU ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Copy L to U, zeroing out above it
*
                     CALL DLACPY( 'L', M, M, A, LDA, U, LDU )
                     CALL DLASET( 'U', M-1, M-1, ZERO, ZERO, U( 1, 2 ),
     $                            LDU )
                     IE = ITAU
                     ITAUQ = IE + M
                     ITAUP = ITAUQ + M
                     IWORK = ITAUP + M
*
*                    Bidiagonalize L in U
*                    (Workspace: need 4*M, prefer 3*M + 2*M*NB)
*
                     CALL DGEBRD( M, M, U, LDU, S, WORK( IE ),
     $                            WORK( ITAUQ ), WORK( ITAUP ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Multiply right bidiagonalizing vectors in U by Q
*                    in VT
*                    (Workspace: need 3*M + N, prefer 3*M + N*NB)
*
                     CALL DORMBR( 'P', 'L', 'T', M, N, M, U, LDU,
     $                            WORK( ITAUP ), VT, LDVT,
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
*
*                    Generate left bidiagonalizing vectors in U
*                    (Workspace: need 4*M, prefer 3*M + M*NB)
*
                     CALL DORGBR( 'Q', M, M, M, U, LDU, WORK( ITAUQ ),
     $                            WORK( IWORK ), LWORK-IWORK+1, IERR )
                     IWORK = IE + M
*
*                    Perform bidiagonal QR iteration, computing left
*                    singular vectors of A in U and computing right
*                    singular vectors of A in VT
*                    (Workspace: need BDSPAC)
*
                     CALL DBDSQR( 'U', M, N, M, 0, S, WORK( IE ), VT,
     $                            LDVT, U, LDU, DUM, 1, WORK( IWORK ),
     $                            INFO )
*
                  END IF
*
               END IF
*
            END IF
*
         ELSE
*
*           N .LT. MNTHR
*
*           Path 10t(N greater than M, but not much larger)
*           Reduce to bidiagonal form without LQ decomposition
*
            IE = 1
            ITAUQ = IE + M
            ITAUP = ITAUQ + M
            IWORK = ITAUP + M
*
*           Bidiagonalize A
*           (Workspace: need 3*M + N, prefer 3*M + (M + N)*NB)
*
            CALL DGEBRD( M, N, A, LDA, S, WORK( IE ), WORK( ITAUQ ),
     $                   WORK( ITAUP ), WORK( IWORK ), LWORK-IWORK+1,
     $                   IERR )
            IF( WNTUAS ) THEN
*
*              If left singular vectors desired in U, copy result to U
*              and generate left bidiagonalizing vectors in U
*              (Workspace: need 4*M-1, prefer 3*M + (M-1)*NB)
*
               CALL DLACPY( 'L', M, M, A, LDA, U, LDU )
               CALL DORGBR( 'Q', M, M, N, U, LDU, WORK( ITAUQ ),
     $                      WORK( IWORK ), LWORK-IWORK+1, IERR )
            END IF
            IF( WNTVAS ) THEN
*
*              If right singular vectors desired in VT, copy result to
*              VT and generate right bidiagonalizing vectors in VT
*              (Workspace: need 3*M + NRVT, prefer 3*M + NRVT*NB)
*
               CALL DLACPY( 'U', M, N, A, LDA, VT, LDVT )
               IF( WNTVA )
     $            NRVT = N
               IF( WNTVS )
     $            NRVT = M
               CALL DORGBR( 'P', NRVT, N, M, VT, LDVT, WORK( ITAUP ),
     $                      WORK( IWORK ), LWORK-IWORK+1, IERR )
            END IF
            IF( WNTUO ) THEN
*
*              If left singular vectors desired in A, generate left
*              bidiagonalizing vectors in A
*              (Workspace: need 4*M-1, prefer 3*M + (M-1)*NB)
*
               CALL DORGBR( 'Q', M, M, N, A, LDA, WORK( ITAUQ ),
     $                      WORK( IWORK ), LWORK-IWORK+1, IERR )
            END IF
            IF( WNTVO ) THEN
*
*              If right singular vectors desired in A, generate right
*              bidiagonalizing vectors in A
*              (Workspace: need 4*M, prefer 3*M + M*NB)
*
               CALL DORGBR( 'P', M, N, M, A, LDA, WORK( ITAUP ),
     $                      WORK( IWORK ), LWORK-IWORK+1, IERR )
            END IF
            IWORK = IE + M
            IF( WNTUAS .OR. WNTUO )
     $         NRU = M
            IF( WNTUN )
     $         NRU = 0
            IF( WNTVAS .OR. WNTVO )
     $         NCVT = N
            IF( WNTVN )
     $         NCVT = 0
            IF( ( .NOT.WNTUO ) .AND. ( .NOT.WNTVO ) ) THEN
*
*              Perform bidiagonal QR iteration, if desired, computing
*              left singular vectors in U and computing right singular
*              vectors in VT
*              (Workspace: need BDSPAC)
*
               CALL DBDSQR( 'L', M, NCVT, NRU, 0, S, WORK( IE ), VT,
     $                      LDVT, U, LDU, DUM, 1, WORK( IWORK ), INFO )
            ELSE IF( ( .NOT.WNTUO ) .AND. WNTVO ) THEN
*
*              Perform bidiagonal QR iteration, if desired, computing
*              left singular vectors in U and computing right singular
*              vectors in A
*              (Workspace: need BDSPAC)
*
               CALL DBDSQR( 'L', M, NCVT, NRU, 0, S, WORK( IE ), A, LDA,
     $                      U, LDU, DUM, 1, WORK( IWORK ), INFO )
            ELSE
*
*              Perform bidiagonal QR iteration, if desired, computing
*              left singular vectors in A and computing right singular
*              vectors in VT
*              (Workspace: need BDSPAC)
*
               CALL DBDSQR( 'L', M, NCVT, NRU, 0, S, WORK( IE ), VT,
     $                      LDVT, A, LDA, DUM, 1, WORK( IWORK ), INFO )
            END IF
*
         END IF
*
      END IF
*
*     If DBDSQR failed to converge, copy unconverged superdiagonals
*     to WORK( 2:MINMN )
*
      IF( INFO.NE.0 ) THEN
         IF( IE.GT.2 ) THEN
            DO 50 I = 1, MINMN - 1
               WORK( I+1 ) = WORK( I+IE-1 )
   50       CONTINUE
         END IF
         IF( IE.LT.2 ) THEN
            DO 60 I = MINMN - 1, 1, -1
               WORK( I+1 ) = WORK( I+IE-1 )
   60       CONTINUE
         END IF
      END IF
*
*     Undo scaling if necessary
*
      IF( ISCL.EQ.1 ) THEN
         IF( ANRM.GT.BIGNUM )
     $      CALL DLASCL( 'G', 0, 0, BIGNUM, ANRM, MINMN, 1, S, MINMN,
     $                   IERR )
         IF( INFO.NE.0 .AND. ANRM.GT.BIGNUM )
     $      CALL DLASCL( 'G', 0, 0, BIGNUM, ANRM, MINMN-1, 1, WORK( 2 ),
     $                   MINMN, IERR )
         IF( ANRM.LT.SMLNUM )
     $      CALL DLASCL( 'G', 0, 0, SMLNUM, ANRM, MINMN, 1, S, MINMN,
     $                   IERR )
         IF( INFO.NE.0 .AND. ANRM.LT.SMLNUM )
     $      CALL DLASCL( 'G', 0, 0, SMLNUM, ANRM, MINMN-1, 1, WORK( 2 ),
     $                   MINMN, IERR )
      END IF
*
*     Return optimal workspace in WORK(1)
*
      WORK( 1 ) = MAXWRK
*
      RETURN
*
*     End of DGESVD
*
      END
*> \brief \b DGESVJ
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGESVJ + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgesvj.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgesvj.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgesvj.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGESVJ( JOBA, JOBU, JOBV, M, N, A, LDA, SVA, MV, V,
*                          LDV, WORK, LWORK, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, LDA, LDV, LWORK, M, MV, N
*       CHARACTER*1        JOBA, JOBU, JOBV
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   A( LDA, * ), SVA( N ), V( LDV, * ),
*      $                   WORK( LWORK )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGESVJ computes the singular value decomposition (SVD) of a real
*> M-by-N matrix A, where M >= N. The SVD of A is written as
*>                                    [++]   [xx]   [x0]   [xx]
*>              A = U * SIGMA * V^t,  [++] = [xx] * [ox] * [xx]
*>                                    [++]   [xx]
*> where SIGMA is an N-by-N diagonal matrix, U is an M-by-N orthonormal
*> matrix, and V is an N-by-N orthogonal matrix. The diagonal elements
*> of SIGMA are the singular values of A. The columns of U and V are the
*> left and the right singular vectors of A, respectively.
*> DGESVJ can sometimes compute tiny singular values and their singular vectors much
*> more accurately than other SVD routines, see below under Further Details.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] JOBA
*> \verbatim
*>          JOBA is CHARACTER*1
*>          Specifies the structure of A.
*>          = 'L': The input matrix A is lower triangular;
*>          = 'U': The input matrix A is upper triangular;
*>          = 'G': The input matrix A is general M-by-N matrix, M >= N.
*> \endverbatim
*>
*> \param[in] JOBU
*> \verbatim
*>          JOBU is CHARACTER*1
*>          Specifies whether to compute the left singular vectors
*>          (columns of U):
*>          = 'U': The left singular vectors corresponding to the nonzero
*>                 singular values are computed and returned in the leading
*>                 columns of A. See more details in the description of A.
*>                 The default numerical orthogonality threshold is set to
*>                 approximately TOL=CTOL*EPS, CTOL=DSQRT(M), EPS=DLAMCH('E').
*>          = 'C': Analogous to JOBU='U', except that user can control the
*>                 level of numerical orthogonality of the computed left
*>                 singular vectors. TOL can be set to TOL = CTOL*EPS, where
*>                 CTOL is given on input in the array WORK.
*>                 No CTOL smaller than ONE is allowed. CTOL greater
*>                 than 1 / EPS is meaningless. The option 'C'
*>                 can be used if M*EPS is satisfactory orthogonality
*>                 of the computed left singular vectors, so CTOL=M could
*>                 save few sweeps of Jacobi rotations.
*>                 See the descriptions of A and WORK(1).
*>          = 'N': The matrix U is not computed. However, see the
*>                 description of A.
*> \endverbatim
*>
*> \param[in] JOBV
*> \verbatim
*>          JOBV is CHARACTER*1
*>          Specifies whether to compute the right singular vectors, that
*>          is, the matrix V:
*>          = 'V' : the matrix V is computed and returned in the array V
*>          = 'A' : the Jacobi rotations are applied to the MV-by-N
*>                  array V. In other words, the right singular vector
*>                  matrix V is not computed explicitly, instead it is
*>                  applied to an MV-by-N matrix initially stored in the
*>                  first MV rows of V.
*>          = 'N' : the matrix V is not computed and the array V is not
*>                  referenced
*> \endverbatim
*>
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the input matrix A. 1/DLAMCH('E') > M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the input matrix A.
*>          M >= N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the M-by-N matrix A.
*>          On exit :
*>          If JOBU .EQ. 'U' .OR. JOBU .EQ. 'C' :
*>                 If INFO .EQ. 0 :
*>                 RANKA orthonormal columns of U are returned in the
*>                 leading RANKA columns of the array A. Here RANKA <= N
*>                 is the number of computed singular values of A that are
*>                 above the underflow threshold DLAMCH('S'). The singular
*>                 vectors corresponding to underflowed or zero singular
*>                 values are not computed. The value of RANKA is returned
*>                 in the array WORK as RANKA=NINT(WORK(2)). Also see the
*>                 descriptions of SVA and WORK. The computed columns of U
*>                 are mutually numerically orthogonal up to approximately
*>                 TOL=DSQRT(M)*EPS (default); or TOL=CTOL*EPS (JOBU.EQ.'C'),
*>                 see the description of JOBU.
*>                 If INFO .GT. 0 :
*>                 the procedure DGESVJ did not converge in the given number
*>                 of iterations (sweeps). In that case, the computed
*>                 columns of U may not be orthogonal up to TOL. The output
*>                 U (stored in A), SIGMA (given by the computed singular
*>                 values in SVA(1:N)) and V is still a decomposition of the
*>                 input matrix A in the sense that the residual
*>                 ||A-SCALE*U*SIGMA*V^T||_2 / ||A||_2 is small.
*>
*>          If JOBU .EQ. 'N' :
*>                 If INFO .EQ. 0 :
*>                 Note that the left singular vectors are 'for free' in the
*>                 one-sided Jacobi SVD algorithm. However, if only the
*>                 singular values are needed, the level of numerical
*>                 orthogonality of U is not an issue and iterations are
*>                 stopped when the columns of the iterated matrix are
*>                 numerically orthogonal up to approximately M*EPS. Thus,
*>                 on exit, A contains the columns of U scaled with the
*>                 corresponding singular values.
*>                 If INFO .GT. 0 :
*>                 the procedure DGESVJ did not converge in the given number
*>                 of iterations (sweeps).
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,M).
*> \endverbatim
*>
*> \param[out] SVA
*> \verbatim
*>          SVA is DOUBLE PRECISION array, dimension (N)
*>          On exit :
*>          If INFO .EQ. 0 :
*>          depending on the value SCALE = WORK(1), we have:
*>                 If SCALE .EQ. ONE :
*>                 SVA(1:N) contains the computed singular values of A.
*>                 During the computation SVA contains the Euclidean column
*>                 norms of the iterated matrices in the array A.
*>                 If SCALE .NE. ONE :
*>                 The singular values of A are SCALE*SVA(1:N), and this
*>                 factored representation is due to the fact that some of the
*>                 singular values of A might underflow or overflow.
*>          If INFO .GT. 0 :
*>          the procedure DGESVJ did not converge in the given number of
*>          iterations (sweeps) and SCALE*SVA(1:N) may not be accurate.
*> \endverbatim
*>
*> \param[in] MV
*> \verbatim
*>          MV is INTEGER
*>          If JOBV .EQ. 'A', then the product of Jacobi rotations in DGESVJ
*>          is applied to the first MV rows of V. See the description of JOBV.
*> \endverbatim
*>
*> \param[in,out] V
*> \verbatim
*>          V is DOUBLE PRECISION array, dimension (LDV,N)
*>          If JOBV = 'V', then V contains on exit the N-by-N matrix of
*>                         the right singular vectors;
*>          If JOBV = 'A', then V contains the product of the computed right
*>                         singular vector matrix and the initial matrix in
*>                         the array V.
*>          If JOBV = 'N', then V is not referenced.
*> \endverbatim
*>
*> \param[in] LDV
*> \verbatim
*>          LDV is INTEGER
*>          The leading dimension of the array V, LDV .GE. 1.
*>          If JOBV .EQ. 'V', then LDV .GE. max(1,N).
*>          If JOBV .EQ. 'A', then LDV .GE. max(1,MV) .
*> \endverbatim
*>
*> \param[in,out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (LWORK)
*>          On entry :
*>          If JOBU .EQ. 'C' :
*>          WORK(1) = CTOL, where CTOL defines the threshold for convergence.
*>                    The process stops if all columns of A are mutually
*>                    orthogonal up to CTOL*EPS, EPS=DLAMCH('E').
*>                    It is required that CTOL >= ONE, i.e. it is not
*>                    allowed to force the routine to obtain orthogonality
*>                    below EPS.
*>          On exit :
*>          WORK(1) = SCALE is the scaling factor such that SCALE*SVA(1:N)
*>                    are the computed singular values of A.
*>                    (See description of SVA().)
*>          WORK(2) = NINT(WORK(2)) is the number of the computed nonzero
*>                    singular values.
*>          WORK(3) = NINT(WORK(3)) is the number of the computed singular
*>                    values that are larger than the underflow threshold.
*>          WORK(4) = NINT(WORK(4)) is the number of sweeps of Jacobi
*>                    rotations needed for numerical convergence.
*>          WORK(5) = max_{i.NE.j} |COS(A(:,i),A(:,j))| in the last sweep.
*>                    This is useful information in cases when DGESVJ did
*>                    not converge, as it can be used to estimate whether
*>                    the output is stil useful and for post festum analysis.
*>          WORK(6) = the largest absolute value over all sines of the
*>                    Jacobi rotation angles in the last sweep. It can be
*>                    useful for a post festum analysis.
*> \endverbatim
*>
*> \param[in] LWORK
*> \verbatim
*>          LWORK is INTEGER
*>          length of WORK, WORK >= MAX(6,M+N)
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0 : successful exit.
*>          < 0 : if INFO = -i, then the i-th argument had an illegal value
*>          > 0 : DGESVJ did not converge in the maximal allowed number (30)
*>                of sweeps. The output may still be useful. See the
*>                description of WORK.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date June 2017
*
*> \ingroup doubleGEcomputational
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>  The orthogonal N-by-N matrix V is obtained as a product of Jacobi plane
*>  rotations. The rotations are implemented as fast scaled rotations of
*>  Anda and Park [1]. In the case of underflow of the Jacobi angle, a
*>  modified Jacobi transformation of Drmac [4] is used. Pivot strategy uses
*>  column interchanges of de Rijk [2]. The relative accuracy of the computed
*>  singular values and the accuracy of the computed singular vectors (in
*>  angle metric) is as guaranteed by the theory of Demmel and Veselic [3].
*>  The condition number that determines the accuracy in the full rank case
*>  is essentially min_{D=diag} kappa(A*D), where kappa(.) is the
*>  spectral condition number. The best performance of this Jacobi SVD
*>  procedure is achieved if used in an  accelerated version of Drmac and
*>  Veselic [5,6], and it is the kernel routine in the SIGMA library [7].
*>  Some tunning parameters (marked with [TP]) are available for the
*>  implementer.
*>  The computational range for the nonzero singular values is the  machine
*>  number interval ( UNDERFLOW , OVERFLOW ). In extreme cases, even
*>  denormalized singular values can be computed with the corresponding
*>  gradual loss of accurate digits.
*> \endverbatim
*
*> \par Contributors:
*  ==================
*>
*> \verbatim
*>
*>  ============
*>
*>  Zlatko Drmac (Zagreb, Croatia) and Kresimir Veselic (Hagen, Germany)
*> \endverbatim
*
*> \par References:
*  ================
*>
*> \verbatim
*>
*> [1] A. A. Anda and H. Park: Fast plane rotations with dynamic scaling.
*>     SIAM J. matrix Anal. Appl., Vol. 15 (1994), pp. 162-174.
*> [2] P. P. M. De Rijk: A one-sided Jacobi algorithm for computing the
*>     singular value decomposition on a vector computer.
*>     SIAM J. Sci. Stat. Comp., Vol. 10 (1998), pp. 359-371.
*> [3] J. Demmel and K. Veselic: Jacobi method is more accurate than QR.
*> [4] Z. Drmac: Implementation of Jacobi rotations for accurate singular
*>     value computation in floating point arithmetic.
*>     SIAM J. Sci. Comp., Vol. 18 (1997), pp. 1200-1222.
*> [5] Z. Drmac and K. Veselic: New fast and accurate Jacobi SVD algorithm I.
*>     SIAM J. Matrix Anal. Appl. Vol. 35, No. 2 (2008), pp. 1322-1342.
*>     LAPACK Working note 169.
*> [6] Z. Drmac and K. Veselic: New fast and accurate Jacobi SVD algorithm II.
*>     SIAM J. Matrix Anal. Appl. Vol. 35, No. 2 (2008), pp. 1343-1362.
*>     LAPACK Working note 170.
*> [7] Z. Drmac: SIGMA - mathematical software library for accurate SVD, PSV,
*>     QSVD, (H,K)-SVD computations.
*>     Department of Mathematics, University of Zagreb, 2008.
*> \endverbatim
*
*>  \par Bugs, examples and comments:
*   =================================
*>
*> \verbatim
*>  ===========================
*>  Please report all bugs and send interesting test examples and comments to
*>  drmac@math.hr. Thank you.
*> \endverbatim
*>
*  =====================================================================
      SUBROUTINE DGESVJ( JOBA, JOBU, JOBV, M, N, A, LDA, SVA, MV, V,
     $                   LDV, WORK, LWORK, INFO )
*
*  -- LAPACK computational routine (version 3.7.1) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     June 2017
*
*     .. Scalar Arguments ..
      INTEGER            INFO, LDA, LDV, LWORK, M, MV, N
      CHARACTER*1        JOBA, JOBU, JOBV
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   A( LDA, * ), SVA( N ), V( LDV, * ),
     $                   WORK( LWORK )
*     ..
*
*  =====================================================================
*
*     .. Local Parameters ..
      DOUBLE PRECISION   ZERO, HALF, ONE
      PARAMETER          ( ZERO = 0.0D0, HALF = 0.5D0, ONE = 1.0D0)
      INTEGER            NSWEEP
      PARAMETER          ( NSWEEP = 30 )
*     ..
*     .. Local Scalars ..
      DOUBLE PRECISION   AAPP, AAPP0, AAPQ, AAQQ, APOAQ, AQOAP, BIG,
     $                   BIGTHETA, CS, CTOL, EPSLN, LARGE, MXAAPQ,
     $                   MXSINJ, ROOTBIG, ROOTEPS, ROOTSFMIN, ROOTTOL,
     $                   SKL, SFMIN, SMALL, SN, T, TEMP1, THETA,
     $                   THSIGN, TOL
      INTEGER            BLSKIP, EMPTSW, i, ibr, IERR, igl, IJBLSK, ir1,
     $                   ISWROT, jbc, jgl, KBL, LKAHEAD, MVL, N2, N34,
     $                   N4, NBL, NOTROT, p, PSKIPPED, q, ROWSKIP,
     $                   SWBAND
      LOGICAL            APPLV, GOSCALE, LOWER, LSVEC, NOSCALE, ROTOK,
     $                   RSVEC, UCTOL, UPPER
*     ..
*     .. Local Arrays ..
      DOUBLE PRECISION   FASTR( 5 )
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          DABS, MAX, MIN, DBLE, DSIGN, DSQRT
*     ..
*     .. External Functions ..
*     ..
*     from BLAS
      DOUBLE PRECISION   DDOT, DNRM2
      EXTERNAL           DDOT, DNRM2
      INTEGER            IDAMAX
      EXTERNAL           IDAMAX
*     from LAPACK
      DOUBLE PRECISION   DLAMCH
      EXTERNAL           DLAMCH
      LOGICAL            LSAME
      EXTERNAL           LSAME
*     ..
*     .. External Subroutines ..
*     ..
*     from BLAS
      EXTERNAL           DAXPY, DCOPY, DROTM, DSCAL, DSWAP
*     from LAPACK
      EXTERNAL           DLASCL, DLASET, DLASSQ, XERBLA
*
      EXTERNAL           DGSVJ0, DGSVJ1
*     ..
*     .. Executable Statements ..
*
*     Test the input arguments
*
      LSVEC = LSAME( JOBU, 'U' )
      UCTOL = LSAME( JOBU, 'C' )
      RSVEC = LSAME( JOBV, 'V' )
      APPLV = LSAME( JOBV, 'A' )
      UPPER = LSAME( JOBA, 'U' )
      LOWER = LSAME( JOBA, 'L' )
*
      IF( .NOT.( UPPER .OR. LOWER .OR. LSAME( JOBA, 'G' ) ) ) THEN
         INFO = -1
      ELSE IF( .NOT.( LSVEC .OR. UCTOL .OR. LSAME( JOBU, 'N' ) ) ) THEN
         INFO = -2
      ELSE IF( .NOT.( RSVEC .OR. APPLV .OR. LSAME( JOBV, 'N' ) ) ) THEN
         INFO = -3
      ELSE IF( M.LT.0 ) THEN
         INFO = -4
      ELSE IF( ( N.LT.0 ) .OR. ( N.GT.M ) ) THEN
         INFO = -5
      ELSE IF( LDA.LT.M ) THEN
         INFO = -7
      ELSE IF( MV.LT.0 ) THEN
         INFO = -9
      ELSE IF( ( RSVEC .AND. ( LDV.LT.N ) ) .OR.
     $         ( APPLV .AND. ( LDV.LT.MV ) ) ) THEN
         INFO = -11
      ELSE IF( UCTOL .AND. ( WORK( 1 ).LE.ONE ) ) THEN
         INFO = -12
      ELSE IF( LWORK.LT.MAX( M+N, 6 ) ) THEN
         INFO = -13
      ELSE
         INFO = 0
      END IF
*
*     #:(
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGESVJ', -INFO )
         RETURN
      END IF
*
* #:) Quick return for void matrix
*
      IF( ( M.EQ.0 ) .OR. ( N.EQ.0 ) )RETURN
*
*     Set numerical parameters
*     The stopping criterion for Jacobi rotations is
*
*     max_{i<>j}|A(:,i)^T * A(:,j)|/(||A(:,i)||*||A(:,j)||) < CTOL*EPS
*
*     where EPS is the round-off and CTOL is defined as follows:
*
      IF( UCTOL ) THEN
*        ... user controlled
         CTOL = WORK( 1 )
      ELSE
*        ... default
         IF( LSVEC .OR. RSVEC .OR. APPLV ) THEN
            CTOL = DSQRT( DBLE( M ) )
         ELSE
            CTOL = DBLE( M )
         END IF
      END IF
*     ... and the machine dependent parameters are
*[!]  (Make sure that DLAMCH() works properly on the target machine.)
*
      EPSLN = DLAMCH( 'Epsilon' )
      ROOTEPS = DSQRT( EPSLN )
      SFMIN = DLAMCH( 'SafeMinimum' )
      ROOTSFMIN = DSQRT( SFMIN )
      SMALL = SFMIN / EPSLN
      BIG = DLAMCH( 'Overflow' )
*     BIG         = ONE    / SFMIN
      ROOTBIG = ONE / ROOTSFMIN
      LARGE = BIG / DSQRT( DBLE( M*N ) )
      BIGTHETA = ONE / ROOTEPS
*
      TOL = CTOL*EPSLN
      ROOTTOL = DSQRT( TOL )
*
      IF( DBLE( M )*EPSLN.GE.ONE ) THEN
         INFO = -4
         CALL XERBLA( 'DGESVJ', -INFO )
         RETURN
      END IF
*
*     Initialize the right singular vector matrix.
*
      IF( RSVEC ) THEN
         MVL = N
         CALL DLASET( 'A', MVL, N, ZERO, ONE, V, LDV )
      ELSE IF( APPLV ) THEN
         MVL = MV
      END IF
      RSVEC = RSVEC .OR. APPLV
*
*     Initialize SVA( 1:N ) = ( ||A e_i||_2, i = 1:N )
*(!)  If necessary, scale A to protect the largest singular value
*     from overflow. It is possible that saving the largest singular
*     value destroys the information about the small ones.
*     This initial scaling is almost minimal in the sense that the
*     goal is to make sure that no column norm overflows, and that
*     DSQRT(N)*max_i SVA(i) does not overflow. If INFinite entries
*     in A are detected, the procedure returns with INFO=-6.
*
      SKL= ONE / DSQRT( DBLE( M )*DBLE( N ) )
      NOSCALE = .TRUE.
      GOSCALE = .TRUE.
*
      IF( LOWER ) THEN
*        the input matrix is M-by-N lower triangular (trapezoidal)
         DO 1874 p = 1, N
            AAPP = ZERO
            AAQQ = ONE
            CALL DLASSQ( M-p+1, A( p, p ), 1, AAPP, AAQQ )
            IF( AAPP.GT.BIG ) THEN
               INFO = -6
               CALL XERBLA( 'DGESVJ', -INFO )
               RETURN
            END IF
            AAQQ = DSQRT( AAQQ )
            IF( ( AAPP.LT.( BIG / AAQQ ) ) .AND. NOSCALE ) THEN
               SVA( p ) = AAPP*AAQQ
            ELSE
               NOSCALE = .FALSE.
               SVA( p ) = AAPP*( AAQQ*SKL)
               IF( GOSCALE ) THEN
                  GOSCALE = .FALSE.
                  DO 1873 q = 1, p - 1
                     SVA( q ) = SVA( q )*SKL
 1873             CONTINUE
               END IF
            END IF
 1874    CONTINUE
      ELSE IF( UPPER ) THEN
*        the input matrix is M-by-N upper triangular (trapezoidal)
         DO 2874 p = 1, N
            AAPP = ZERO
            AAQQ = ONE
            CALL DLASSQ( p, A( 1, p ), 1, AAPP, AAQQ )
            IF( AAPP.GT.BIG ) THEN
               INFO = -6
               CALL XERBLA( 'DGESVJ', -INFO )
               RETURN
            END IF
            AAQQ = DSQRT( AAQQ )
            IF( ( AAPP.LT.( BIG / AAQQ ) ) .AND. NOSCALE ) THEN
               SVA( p ) = AAPP*AAQQ
            ELSE
               NOSCALE = .FALSE.
               SVA( p ) = AAPP*( AAQQ*SKL)
               IF( GOSCALE ) THEN
                  GOSCALE = .FALSE.
                  DO 2873 q = 1, p - 1
                     SVA( q ) = SVA( q )*SKL
 2873             CONTINUE
               END IF
            END IF
 2874    CONTINUE
      ELSE
*        the input matrix is M-by-N general dense
         DO 3874 p = 1, N
            AAPP = ZERO
            AAQQ = ONE
            CALL DLASSQ( M, A( 1, p ), 1, AAPP, AAQQ )
            IF( AAPP.GT.BIG ) THEN
               INFO = -6
               CALL XERBLA( 'DGESVJ', -INFO )
               RETURN
            END IF
            AAQQ = DSQRT( AAQQ )
            IF( ( AAPP.LT.( BIG / AAQQ ) ) .AND. NOSCALE ) THEN
               SVA( p ) = AAPP*AAQQ
            ELSE
               NOSCALE = .FALSE.
               SVA( p ) = AAPP*( AAQQ*SKL)
               IF( GOSCALE ) THEN
                  GOSCALE = .FALSE.
                  DO 3873 q = 1, p - 1
                     SVA( q ) = SVA( q )*SKL
 3873             CONTINUE
               END IF
            END IF
 3874    CONTINUE
      END IF
*
      IF( NOSCALE )SKL= ONE
*
*     Move the smaller part of the spectrum from the underflow threshold
*(!)  Start by determining the position of the nonzero entries of the
*     array SVA() relative to ( SFMIN, BIG ).
*
      AAPP = ZERO
      AAQQ = BIG
      DO 4781 p = 1, N
         IF( SVA( p ).NE.ZERO )AAQQ = MIN( AAQQ, SVA( p ) )
         AAPP = MAX( AAPP, SVA( p ) )
 4781 CONTINUE
*
* #:) Quick return for zero matrix
*
      IF( AAPP.EQ.ZERO ) THEN
         IF( LSVEC )CALL DLASET( 'G', M, N, ZERO, ONE, A, LDA )
         WORK( 1 ) = ONE
         WORK( 2 ) = ZERO
         WORK( 3 ) = ZERO
         WORK( 4 ) = ZERO
         WORK( 5 ) = ZERO
         WORK( 6 ) = ZERO
         RETURN
      END IF
*
* #:) Quick return for one-column matrix
*
      IF( N.EQ.1 ) THEN
         IF( LSVEC )CALL DLASCL( 'G', 0, 0, SVA( 1 ), SKL, M, 1,
     $                           A( 1, 1 ), LDA, IERR )
         WORK( 1 ) = ONE / SKL
         IF( SVA( 1 ).GE.SFMIN ) THEN
            WORK( 2 ) = ONE
         ELSE
            WORK( 2 ) = ZERO
         END IF
         WORK( 3 ) = ZERO
         WORK( 4 ) = ZERO
         WORK( 5 ) = ZERO
         WORK( 6 ) = ZERO
         RETURN
      END IF
*
*     Protect small singular values from underflow, and try to
*     avoid underflows/overflows in computing Jacobi rotations.
*
      SN = DSQRT( SFMIN / EPSLN )
      TEMP1 = DSQRT( BIG / DBLE( N ) )
      IF( ( AAPP.LE.SN ) .OR. ( AAQQ.GE.TEMP1 ) .OR.
     $    ( ( SN.LE.AAQQ ) .AND. ( AAPP.LE.TEMP1 ) ) ) THEN
         TEMP1 = MIN( BIG, TEMP1 / AAPP )
*         AAQQ  = AAQQ*TEMP1
*         AAPP  = AAPP*TEMP1
      ELSE IF( ( AAQQ.LE.SN ) .AND. ( AAPP.LE.TEMP1 ) ) THEN
         TEMP1 = MIN( SN / AAQQ, BIG / ( AAPP*DSQRT( DBLE( N ) ) ) )
*         AAQQ  = AAQQ*TEMP1
*         AAPP  = AAPP*TEMP1
      ELSE IF( ( AAQQ.GE.SN ) .AND. ( AAPP.GE.TEMP1 ) ) THEN
         TEMP1 = MAX( SN / AAQQ, TEMP1 / AAPP )
*         AAQQ  = AAQQ*TEMP1
*         AAPP  = AAPP*TEMP1
      ELSE IF( ( AAQQ.LE.SN ) .AND. ( AAPP.GE.TEMP1 ) ) THEN
         TEMP1 = MIN( SN / AAQQ, BIG / ( DSQRT( DBLE( N ) )*AAPP ) )
*         AAQQ  = AAQQ*TEMP1
*         AAPP  = AAPP*TEMP1
      ELSE
         TEMP1 = ONE
      END IF
*
*     Scale, if necessary
*
      IF( TEMP1.NE.ONE ) THEN
         CALL DLASCL( 'G', 0, 0, ONE, TEMP1, N, 1, SVA, N, IERR )
      END IF
      SKL= TEMP1*SKL
      IF( SKL.NE.ONE ) THEN
         CALL DLASCL( JOBA, 0, 0, ONE, SKL, M, N, A, LDA, IERR )
         SKL= ONE / SKL
      END IF
*
*     Row-cyclic Jacobi SVD algorithm with column pivoting
*
      EMPTSW = ( N*( N-1 ) ) / 2
      NOTROT = 0
      FASTR( 1 ) = ZERO
*
*     A is represented in factored form A = A * diag(WORK), where diag(WORK)
*     is initialized to identity. WORK is updated during fast scaled
*     rotations.
*
      DO 1868 q = 1, N
         WORK( q ) = ONE
 1868 CONTINUE
*
*
      SWBAND = 3
*[TP] SWBAND is a tuning parameter [TP]. It is meaningful and effective
*     if DGESVJ is used as a computational routine in the preconditioned
*     Jacobi SVD algorithm DGESVJ. For sweeps i=1:SWBAND the procedure
*     works on pivots inside a band-like region around the diagonal.
*     The boundaries are determined dynamically, based on the number of
*     pivots above a threshold.
*
      KBL = MIN( 8, N )
*[TP] KBL is a tuning parameter that defines the tile size in the
*     tiling of the p-q loops of pivot pairs. In general, an optimal
*     value of KBL depends on the matrix dimensions and on the
*     parameters of the computer's memory.
*
      NBL = N / KBL
      IF( ( NBL*KBL ).NE.N )NBL = NBL + 1
*
      BLSKIP = KBL**2
*[TP] BLKSKIP is a tuning parameter that depends on SWBAND and KBL.
*
      ROWSKIP = MIN( 5, KBL )
*[TP] ROWSKIP is a tuning parameter.
*
      LKAHEAD = 1
*[TP] LKAHEAD is a tuning parameter.
*
*     Quasi block transformations, using the lower (upper) triangular
*     structure of the input matrix. The quasi-block-cycling usually
*     invokes cubic convergence. Big part of this cycle is done inside
*     canonical subspaces of dimensions less than M.
*
      IF( ( LOWER .OR. UPPER ) .AND. ( N.GT.MAX( 64, 4*KBL ) ) ) THEN
*[TP] The number of partition levels and the actual partition are
*     tuning parameters.
         N4 = N / 4
         N2 = N / 2
         N34 = 3*N4
         IF( APPLV ) THEN
            q = 0
         ELSE
            q = 1
         END IF
*
         IF( LOWER ) THEN
*
*     This works very well on lower triangular matrices, in particular
*     in the framework of the preconditioned Jacobi SVD (xGEJSV).
*     The idea is simple:
*     [+ 0 0 0]   Note that Jacobi transformations of [0 0]
*     [+ + 0 0]                                       [0 0]
*     [+ + x 0]   actually work on [x 0]              [x 0]
*     [+ + x x]                    [x x].             [x x]
*
            CALL DGSVJ0( JOBV, M-N34, N-N34, A( N34+1, N34+1 ), LDA,
     $                   WORK( N34+1 ), SVA( N34+1 ), MVL,
     $                   V( N34*q+1, N34+1 ), LDV, EPSLN, SFMIN, TOL,
     $                   2, WORK( N+1 ), LWORK-N, IERR )
*
            CALL DGSVJ0( JOBV, M-N2, N34-N2, A( N2+1, N2+1 ), LDA,
     $                   WORK( N2+1 ), SVA( N2+1 ), MVL,
     $                   V( N2*q+1, N2+1 ), LDV, EPSLN, SFMIN, TOL, 2,
     $                   WORK( N+1 ), LWORK-N, IERR )
*
            CALL DGSVJ1( JOBV, M-N2, N-N2, N4, A( N2+1, N2+1 ), LDA,
     $                   WORK( N2+1 ), SVA( N2+1 ), MVL,
     $                   V( N2*q+1, N2+1 ), LDV, EPSLN, SFMIN, TOL, 1,
     $                   WORK( N+1 ), LWORK-N, IERR )
*
            CALL DGSVJ0( JOBV, M-N4, N2-N4, A( N4+1, N4+1 ), LDA,
     $                   WORK( N4+1 ), SVA( N4+1 ), MVL,
     $                   V( N4*q+1, N4+1 ), LDV, EPSLN, SFMIN, TOL, 1,
     $                   WORK( N+1 ), LWORK-N, IERR )
*
            CALL DGSVJ0( JOBV, M, N4, A, LDA, WORK, SVA, MVL, V, LDV,
     $                   EPSLN, SFMIN, TOL, 1, WORK( N+1 ), LWORK-N,
     $                   IERR )
*
            CALL DGSVJ1( JOBV, M, N2, N4, A, LDA, WORK, SVA, MVL, V,
     $                   LDV, EPSLN, SFMIN, TOL, 1, WORK( N+1 ),
     $                   LWORK-N, IERR )
*
*
         ELSE IF( UPPER ) THEN
*
*
            CALL DGSVJ0( JOBV, N4, N4, A, LDA, WORK, SVA, MVL, V, LDV,
     $                   EPSLN, SFMIN, TOL, 2, WORK( N+1 ), LWORK-N,
     $                   IERR )
*
            CALL DGSVJ0( JOBV, N2, N4, A( 1, N4+1 ), LDA, WORK( N4+1 ),
     $                   SVA( N4+1 ), MVL, V( N4*q+1, N4+1 ), LDV,
     $                   EPSLN, SFMIN, TOL, 1, WORK( N+1 ), LWORK-N,
     $                   IERR )
*
            CALL DGSVJ1( JOBV, N2, N2, N4, A, LDA, WORK, SVA, MVL, V,
     $                   LDV, EPSLN, SFMIN, TOL, 1, WORK( N+1 ),
     $                   LWORK-N, IERR )
*
            CALL DGSVJ0( JOBV, N2+N4, N4, A( 1, N2+1 ), LDA,
     $                   WORK( N2+1 ), SVA( N2+1 ), MVL,
     $                   V( N2*q+1, N2+1 ), LDV, EPSLN, SFMIN, TOL, 1,
     $                   WORK( N+1 ), LWORK-N, IERR )

         END IF
*
      END IF
*
*     .. Row-cyclic pivot strategy with de Rijk's pivoting ..
*
      DO 1993 i = 1, NSWEEP
*
*     .. go go go ...
*
         MXAAPQ = ZERO
         MXSINJ = ZERO
         ISWROT = 0
*
         NOTROT = 0
         PSKIPPED = 0
*
*     Each sweep is unrolled using KBL-by-KBL tiles over the pivot pairs
*     1 <= p < q <= N. This is the first step toward a blocked implementation
*     of the rotations. New implementation, based on block transformations,
*     is under development.
*
         DO 2000 ibr = 1, NBL
*
            igl = ( ibr-1 )*KBL + 1
*
            DO 1002 ir1 = 0, MIN( LKAHEAD, NBL-ibr )
*
               igl = igl + ir1*KBL
*
               DO 2001 p = igl, MIN( igl+KBL-1, N-1 )
*
*     .. de Rijk's pivoting
*
                  q = IDAMAX( N-p+1, SVA( p ), 1 ) + p - 1
                  IF( p.NE.q ) THEN
                     CALL DSWAP( M, A( 1, p ), 1, A( 1, q ), 1 )
                     IF( RSVEC )CALL DSWAP( MVL, V( 1, p ), 1,
     $                                      V( 1, q ), 1 )
                     TEMP1 = SVA( p )
                     SVA( p ) = SVA( q )
                     SVA( q ) = TEMP1
                     TEMP1 = WORK( p )
                     WORK( p ) = WORK( q )
                     WORK( q ) = TEMP1
                  END IF
*
                  IF( ir1.EQ.0 ) THEN
*
*        Column norms are periodically updated by explicit
*        norm computation.
*        Caveat:
*        Unfortunately, some BLAS implementations compute DNRM2(M,A(1,p),1)
*        as DSQRT(DDOT(M,A(1,p),1,A(1,p),1)), which may cause the result to
*        overflow for ||A(:,p)||_2 > DSQRT(overflow_threshold), and to
*        underflow for ||A(:,p)||_2 < DSQRT(underflow_threshold).
*        Hence, DNRM2 cannot be trusted, not even in the case when
*        the true norm is far from the under(over)flow boundaries.
*        If properly implemented DNRM2 is available, the IF-THEN-ELSE
*        below should read "AAPP = DNRM2( M, A(1,p), 1 ) * WORK(p)".
*
                     IF( ( SVA( p ).LT.ROOTBIG ) .AND.
     $                   ( SVA( p ).GT.ROOTSFMIN ) ) THEN
                        SVA( p ) = DNRM2( M, A( 1, p ), 1 )*WORK( p )
                     ELSE
                        TEMP1 = ZERO
                        AAPP = ONE
                        CALL DLASSQ( M, A( 1, p ), 1, TEMP1, AAPP )
                        SVA( p ) = TEMP1*DSQRT( AAPP )*WORK( p )
                     END IF
                     AAPP = SVA( p )
                  ELSE
                     AAPP = SVA( p )
                  END IF
*
                  IF( AAPP.GT.ZERO ) THEN
*
                     PSKIPPED = 0
*
                     DO 2002 q = p + 1, MIN( igl+KBL-1, N )
*
                        AAQQ = SVA( q )
*
                        IF( AAQQ.GT.ZERO ) THEN
*
                           AAPP0 = AAPP
                           IF( AAQQ.GE.ONE ) THEN
                              ROTOK = ( SMALL*AAPP ).LE.AAQQ
                              IF( AAPP.LT.( BIG / AAQQ ) ) THEN
                                 AAPQ = ( DDOT( M, A( 1, p ), 1, A( 1,
     $                                  q ), 1 )*WORK( p )*WORK( q ) /
     $                                  AAQQ ) / AAPP
                              ELSE
                                 CALL DCOPY( M, A( 1, p ), 1,
     $                                       WORK( N+1 ), 1 )
                                 CALL DLASCL( 'G', 0, 0, AAPP,
     $                                        WORK( p ), M, 1,
     $                                        WORK( N+1 ), LDA, IERR )
                                 AAPQ = DDOT( M, WORK( N+1 ), 1,
     $                                  A( 1, q ), 1 )*WORK( q ) / AAQQ
                              END IF
                           ELSE
                              ROTOK = AAPP.LE.( AAQQ / SMALL )
                              IF( AAPP.GT.( SMALL / AAQQ ) ) THEN
                                 AAPQ = ( DDOT( M, A( 1, p ), 1, A( 1,
     $                                  q ), 1 )*WORK( p )*WORK( q ) /
     $                                  AAQQ ) / AAPP
                              ELSE
                                 CALL DCOPY( M, A( 1, q ), 1,
     $                                       WORK( N+1 ), 1 )
                                 CALL DLASCL( 'G', 0, 0, AAQQ,
     $                                        WORK( q ), M, 1,
     $                                        WORK( N+1 ), LDA, IERR )
                                 AAPQ = DDOT( M, WORK( N+1 ), 1,
     $                                  A( 1, p ), 1 )*WORK( p ) / AAPP
                              END IF
                           END IF
*
                           MXAAPQ = MAX( MXAAPQ, DABS( AAPQ ) )
*
*        TO rotate or NOT to rotate, THAT is the question ...
*
                           IF( DABS( AAPQ ).GT.TOL ) THEN
*
*           .. rotate
*[RTD]      ROTATED = ROTATED + ONE
*
                              IF( ir1.EQ.0 ) THEN
                                 NOTROT = 0
                                 PSKIPPED = 0
                                 ISWROT = ISWROT + 1
                              END IF
*
                              IF( ROTOK ) THEN
*
                                 AQOAP = AAQQ / AAPP
                                 APOAQ = AAPP / AAQQ
                                 THETA = -HALF*DABS(AQOAP-APOAQ)/AAPQ
*
                                 IF( DABS( THETA ).GT.BIGTHETA ) THEN
*
                                    T = HALF / THETA
                                    FASTR( 3 ) = T*WORK( p ) / WORK( q )
                                    FASTR( 4 ) = -T*WORK( q ) /
     $                                           WORK( p )
                                    CALL DROTM( M, A( 1, p ), 1,
     $                                          A( 1, q ), 1, FASTR )
                                    IF( RSVEC )CALL DROTM( MVL,
     $                                              V( 1, p ), 1,
     $                                              V( 1, q ), 1,
     $                                              FASTR )
                                    SVA( q ) = AAQQ*DSQRT( MAX( ZERO,
     $                                         ONE+T*APOAQ*AAPQ ) )
                                    AAPP = AAPP*DSQRT( MAX( ZERO,
     $                                     ONE-T*AQOAP*AAPQ ) )
                                    MXSINJ = MAX( MXSINJ, DABS( T ) )
*
                                 ELSE
*
*                 .. choose correct signum for THETA and rotate
*
                                    THSIGN = -DSIGN( ONE, AAPQ )
                                    T = ONE / ( THETA+THSIGN*
     $                                  DSQRT( ONE+THETA*THETA ) )
                                    CS = DSQRT( ONE / ( ONE+T*T ) )
                                    SN = T*CS
*
                                    MXSINJ = MAX( MXSINJ, DABS( SN ) )
                                    SVA( q ) = AAQQ*DSQRT( MAX( ZERO,
     $                                         ONE+T*APOAQ*AAPQ ) )
                                    AAPP = AAPP*DSQRT( MAX( ZERO,
     $                                     ONE-T*AQOAP*AAPQ ) )
*
                                    APOAQ = WORK( p ) / WORK( q )
                                    AQOAP = WORK( q ) / WORK( p )
                                    IF( WORK( p ).GE.ONE ) THEN
                                       IF( WORK( q ).GE.ONE ) THEN
                                          FASTR( 3 ) = T*APOAQ
                                          FASTR( 4 ) = -T*AQOAP
                                          WORK( p ) = WORK( p )*CS
                                          WORK( q ) = WORK( q )*CS
                                          CALL DROTM( M, A( 1, p ), 1,
     $                                                A( 1, q ), 1,
     $                                                FASTR )
                                          IF( RSVEC )CALL DROTM( MVL,
     $                                        V( 1, p ), 1, V( 1, q ),
     $                                        1, FASTR )
                                       ELSE
                                          CALL DAXPY( M, -T*AQOAP,
     $                                                A( 1, q ), 1,
     $                                                A( 1, p ), 1 )
                                          CALL DAXPY( M, CS*SN*APOAQ,
     $                                                A( 1, p ), 1,
     $                                                A( 1, q ), 1 )
                                          WORK( p ) = WORK( p )*CS
                                          WORK( q ) = WORK( q ) / CS
                                          IF( RSVEC ) THEN
                                             CALL DAXPY( MVL, -T*AQOAP,
     $                                                   V( 1, q ), 1,
     $                                                   V( 1, p ), 1 )
                                             CALL DAXPY( MVL,
     $                                                   CS*SN*APOAQ,
     $                                                   V( 1, p ), 1,
     $                                                   V( 1, q ), 1 )
                                          END IF
                                       END IF
                                    ELSE
                                       IF( WORK( q ).GE.ONE ) THEN
                                          CALL DAXPY( M, T*APOAQ,
     $                                                A( 1, p ), 1,
     $                                                A( 1, q ), 1 )
                                          CALL DAXPY( M, -CS*SN*AQOAP,
     $                                                A( 1, q ), 1,
     $                                                A( 1, p ), 1 )
                                          WORK( p ) = WORK( p ) / CS
                                          WORK( q ) = WORK( q )*CS
                                          IF( RSVEC ) THEN
                                             CALL DAXPY( MVL, T*APOAQ,
     $                                                   V( 1, p ), 1,
     $                                                   V( 1, q ), 1 )
                                             CALL DAXPY( MVL,
     $                                                   -CS*SN*AQOAP,
     $                                                   V( 1, q ), 1,
     $                                                   V( 1, p ), 1 )
                                          END IF
                                       ELSE
                                          IF( WORK( p ).GE.WORK( q ) )
     $                                        THEN
                                             CALL DAXPY( M, -T*AQOAP,
     $                                                   A( 1, q ), 1,
     $                                                   A( 1, p ), 1 )
                                             CALL DAXPY( M, CS*SN*APOAQ,
     $                                                   A( 1, p ), 1,
     $                                                   A( 1, q ), 1 )
                                             WORK( p ) = WORK( p )*CS
                                             WORK( q ) = WORK( q ) / CS
                                             IF( RSVEC ) THEN
                                                CALL DAXPY( MVL,
     $                                               -T*AQOAP,
     $                                               V( 1, q ), 1,
     $                                               V( 1, p ), 1 )
                                                CALL DAXPY( MVL,
     $                                               CS*SN*APOAQ,
     $                                               V( 1, p ), 1,
     $                                               V( 1, q ), 1 )
                                             END IF
                                          ELSE
                                             CALL DAXPY( M, T*APOAQ,
     $                                                   A( 1, p ), 1,
     $                                                   A( 1, q ), 1 )
                                             CALL DAXPY( M,
     $                                                   -CS*SN*AQOAP,
     $                                                   A( 1, q ), 1,
     $                                                   A( 1, p ), 1 )
                                             WORK( p ) = WORK( p ) / CS
                                             WORK( q ) = WORK( q )*CS
                                             IF( RSVEC ) THEN
                                                CALL DAXPY( MVL,
     $                                               T*APOAQ, V( 1, p ),
     $                                               1, V( 1, q ), 1 )
                                                CALL DAXPY( MVL,
     $                                               -CS*SN*AQOAP,
     $                                               V( 1, q ), 1,
     $                                               V( 1, p ), 1 )
                                             END IF
                                          END IF
                                       END IF
                                    END IF
                                 END IF
*
                              ELSE
*              .. have to use modified Gram-Schmidt like transformation
                                 CALL DCOPY( M, A( 1, p ), 1,
     $                                       WORK( N+1 ), 1 )
                                 CALL DLASCL( 'G', 0, 0, AAPP, ONE, M,
     $                                        1, WORK( N+1 ), LDA,
     $                                        IERR )
                                 CALL DLASCL( 'G', 0, 0, AAQQ, ONE, M,
     $                                        1, A( 1, q ), LDA, IERR )
                                 TEMP1 = -AAPQ*WORK( p ) / WORK( q )
                                 CALL DAXPY( M, TEMP1, WORK( N+1 ), 1,
     $                                       A( 1, q ), 1 )
                                 CALL DLASCL( 'G', 0, 0, ONE, AAQQ, M,
     $                                        1, A( 1, q ), LDA, IERR )
                                 SVA( q ) = AAQQ*DSQRT( MAX( ZERO,
     $                                      ONE-AAPQ*AAPQ ) )
                                 MXSINJ = MAX( MXSINJ, SFMIN )
                              END IF
*           END IF ROTOK THEN ... ELSE
*
*           In the case of cancellation in updating SVA(q), SVA(p)
*           recompute SVA(q), SVA(p).
*
                              IF( ( SVA( q ) / AAQQ )**2.LE.ROOTEPS )
     $                            THEN
                                 IF( ( AAQQ.LT.ROOTBIG ) .AND.
     $                               ( AAQQ.GT.ROOTSFMIN ) ) THEN
                                    SVA( q ) = DNRM2( M, A( 1, q ), 1 )*
     $                                         WORK( q )
                                 ELSE
                                    T = ZERO
                                    AAQQ = ONE
                                    CALL DLASSQ( M, A( 1, q ), 1, T,
     $                                           AAQQ )
                                    SVA( q ) = T*DSQRT( AAQQ )*WORK( q )
                                 END IF
                              END IF
                              IF( ( AAPP / AAPP0 ).LE.ROOTEPS ) THEN
                                 IF( ( AAPP.LT.ROOTBIG ) .AND.
     $                               ( AAPP.GT.ROOTSFMIN ) ) THEN
                                    AAPP = DNRM2( M, A( 1, p ), 1 )*
     $                                     WORK( p )
                                 ELSE
                                    T = ZERO
                                    AAPP = ONE
                                    CALL DLASSQ( M, A( 1, p ), 1, T,
     $                                           AAPP )
                                    AAPP = T*DSQRT( AAPP )*WORK( p )
                                 END IF
                                 SVA( p ) = AAPP
                              END IF
*
                           ELSE
*        A(:,p) and A(:,q) already numerically orthogonal
                              IF( ir1.EQ.0 )NOTROT = NOTROT + 1
*[RTD]      SKIPPED  = SKIPPED  + 1
                              PSKIPPED = PSKIPPED + 1
                           END IF
                        ELSE
*        A(:,q) is zero column
                           IF( ir1.EQ.0 )NOTROT = NOTROT + 1
                           PSKIPPED = PSKIPPED + 1
                        END IF
*
                        IF( ( i.LE.SWBAND ) .AND.
     $                      ( PSKIPPED.GT.ROWSKIP ) ) THEN
                           IF( ir1.EQ.0 )AAPP = -AAPP
                           NOTROT = 0
                           GO TO 2103
                        END IF
*
 2002                CONTINUE
*     END q-LOOP
*
 2103                CONTINUE
*     bailed out of q-loop
*
                     SVA( p ) = AAPP
*
                  ELSE
                     SVA( p ) = AAPP
                     IF( ( ir1.EQ.0 ) .AND. ( AAPP.EQ.ZERO ) )
     $                   NOTROT = NOTROT + MIN( igl+KBL-1, N ) - p
                  END IF
*
 2001          CONTINUE
*     end of the p-loop
*     end of doing the block ( ibr, ibr )
 1002       CONTINUE
*     end of ir1-loop
*
* ... go to the off diagonal blocks
*
            igl = ( ibr-1 )*KBL + 1
*
            DO 2010 jbc = ibr + 1, NBL
*
               jgl = ( jbc-1 )*KBL + 1
*
*        doing the block at ( ibr, jbc )
*
               IJBLSK = 0
               DO 2100 p = igl, MIN( igl+KBL-1, N )
*
                  AAPP = SVA( p )
                  IF( AAPP.GT.ZERO ) THEN
*
                     PSKIPPED = 0
*
                     DO 2200 q = jgl, MIN( jgl+KBL-1, N )
*
                        AAQQ = SVA( q )
                        IF( AAQQ.GT.ZERO ) THEN
                           AAPP0 = AAPP
*
*     .. M x 2 Jacobi SVD ..
*
*        Safe Gram matrix computation
*
                           IF( AAQQ.GE.ONE ) THEN
                              IF( AAPP.GE.AAQQ ) THEN
                                 ROTOK = ( SMALL*AAPP ).LE.AAQQ
                              ELSE
                                 ROTOK = ( SMALL*AAQQ ).LE.AAPP
                              END IF
                              IF( AAPP.LT.( BIG / AAQQ ) ) THEN
                                 AAPQ = ( DDOT( M, A( 1, p ), 1, A( 1,
     $                                  q ), 1 )*WORK( p )*WORK( q ) /
     $                                  AAQQ ) / AAPP
                              ELSE
                                 CALL DCOPY( M, A( 1, p ), 1,
     $                                       WORK( N+1 ), 1 )
                                 CALL DLASCL( 'G', 0, 0, AAPP,
     $                                        WORK( p ), M, 1,
     $                                        WORK( N+1 ), LDA, IERR )
                                 AAPQ = DDOT( M, WORK( N+1 ), 1,
     $                                  A( 1, q ), 1 )*WORK( q ) / AAQQ
                              END IF
                           ELSE
                              IF( AAPP.GE.AAQQ ) THEN
                                 ROTOK = AAPP.LE.( AAQQ / SMALL )
                              ELSE
                                 ROTOK = AAQQ.LE.( AAPP / SMALL )
                              END IF
                              IF( AAPP.GT.( SMALL / AAQQ ) ) THEN
                                 AAPQ = ( DDOT( M, A( 1, p ), 1, A( 1,
     $                                  q ), 1 )*WORK( p )*WORK( q ) /
     $                                  AAQQ ) / AAPP
                              ELSE
                                 CALL DCOPY( M, A( 1, q ), 1,
     $                                       WORK( N+1 ), 1 )
                                 CALL DLASCL( 'G', 0, 0, AAQQ,
     $                                        WORK( q ), M, 1,
     $                                        WORK( N+1 ), LDA, IERR )
                                 AAPQ = DDOT( M, WORK( N+1 ), 1,
     $                                  A( 1, p ), 1 )*WORK( p ) / AAPP
                              END IF
                           END IF
*
                           MXAAPQ = MAX( MXAAPQ, DABS( AAPQ ) )
*
*        TO rotate or NOT to rotate, THAT is the question ...
*
                           IF( DABS( AAPQ ).GT.TOL ) THEN
                              NOTROT = 0
*[RTD]      ROTATED  = ROTATED + 1
                              PSKIPPED = 0
                              ISWROT = ISWROT + 1
*
                              IF( ROTOK ) THEN
*
                                 AQOAP = AAQQ / AAPP
                                 APOAQ = AAPP / AAQQ
                                 THETA = -HALF*DABS(AQOAP-APOAQ)/AAPQ
                                 IF( AAQQ.GT.AAPP0 )THETA = -THETA
*
                                 IF( DABS( THETA ).GT.BIGTHETA ) THEN
                                    T = HALF / THETA
                                    FASTR( 3 ) = T*WORK( p ) / WORK( q )
                                    FASTR( 4 ) = -T*WORK( q ) /
     $                                           WORK( p )
                                    CALL DROTM( M, A( 1, p ), 1,
     $                                          A( 1, q ), 1, FASTR )
                                    IF( RSVEC )CALL DROTM( MVL,
     $                                              V( 1, p ), 1,
     $                                              V( 1, q ), 1,
     $                                              FASTR )
                                    SVA( q ) = AAQQ*DSQRT( MAX( ZERO,
     $                                         ONE+T*APOAQ*AAPQ ) )
                                    AAPP = AAPP*DSQRT( MAX( ZERO,
     $                                     ONE-T*AQOAP*AAPQ ) )
                                    MXSINJ = MAX( MXSINJ, DABS( T ) )
                                 ELSE
*
*                 .. choose correct signum for THETA and rotate
*
                                    THSIGN = -DSIGN( ONE, AAPQ )
                                    IF( AAQQ.GT.AAPP0 )THSIGN = -THSIGN
                                    T = ONE / ( THETA+THSIGN*
     $                                  DSQRT( ONE+THETA*THETA ) )
                                    CS = DSQRT( ONE / ( ONE+T*T ) )
                                    SN = T*CS
                                    MXSINJ = MAX( MXSINJ, DABS( SN ) )
                                    SVA( q ) = AAQQ*DSQRT( MAX( ZERO,
     $                                         ONE+T*APOAQ*AAPQ ) )
                                    AAPP = AAPP*DSQRT( MAX( ZERO,
     $                                     ONE-T*AQOAP*AAPQ ) )
*
                                    APOAQ = WORK( p ) / WORK( q )
                                    AQOAP = WORK( q ) / WORK( p )
                                    IF( WORK( p ).GE.ONE ) THEN
*
                                       IF( WORK( q ).GE.ONE ) THEN
                                          FASTR( 3 ) = T*APOAQ
                                          FASTR( 4 ) = -T*AQOAP
                                          WORK( p ) = WORK( p )*CS
                                          WORK( q ) = WORK( q )*CS
                                          CALL DROTM( M, A( 1, p ), 1,
     $                                                A( 1, q ), 1,
     $                                                FASTR )
                                          IF( RSVEC )CALL DROTM( MVL,
     $                                        V( 1, p ), 1, V( 1, q ),
     $                                        1, FASTR )
                                       ELSE
                                          CALL DAXPY( M, -T*AQOAP,
     $                                                A( 1, q ), 1,
     $                                                A( 1, p ), 1 )
                                          CALL DAXPY( M, CS*SN*APOAQ,
     $                                                A( 1, p ), 1,
     $                                                A( 1, q ), 1 )
                                          IF( RSVEC ) THEN
                                             CALL DAXPY( MVL, -T*AQOAP,
     $                                                   V( 1, q ), 1,
     $                                                   V( 1, p ), 1 )
                                             CALL DAXPY( MVL,
     $                                                   CS*SN*APOAQ,
     $                                                   V( 1, p ), 1,
     $                                                   V( 1, q ), 1 )
                                          END IF
                                          WORK( p ) = WORK( p )*CS
                                          WORK( q ) = WORK( q ) / CS
                                       END IF
                                    ELSE
                                       IF( WORK( q ).GE.ONE ) THEN
                                          CALL DAXPY( M, T*APOAQ,
     $                                                A( 1, p ), 1,
     $                                                A( 1, q ), 1 )
                                          CALL DAXPY( M, -CS*SN*AQOAP,
     $                                                A( 1, q ), 1,
     $                                                A( 1, p ), 1 )
                                          IF( RSVEC ) THEN
                                             CALL DAXPY( MVL, T*APOAQ,
     $                                                   V( 1, p ), 1,
     $                                                   V( 1, q ), 1 )
                                             CALL DAXPY( MVL,
     $                                                   -CS*SN*AQOAP,
     $                                                   V( 1, q ), 1,
     $                                                   V( 1, p ), 1 )
                                          END IF
                                          WORK( p ) = WORK( p ) / CS
                                          WORK( q ) = WORK( q )*CS
                                       ELSE
                                          IF( WORK( p ).GE.WORK( q ) )
     $                                        THEN
                                             CALL DAXPY( M, -T*AQOAP,
     $                                                   A( 1, q ), 1,
     $                                                   A( 1, p ), 1 )
                                             CALL DAXPY( M, CS*SN*APOAQ,
     $                                                   A( 1, p ), 1,
     $                                                   A( 1, q ), 1 )
                                             WORK( p ) = WORK( p )*CS
                                             WORK( q ) = WORK( q ) / CS
                                             IF( RSVEC ) THEN
                                                CALL DAXPY( MVL,
     $                                               -T*AQOAP,
     $                                               V( 1, q ), 1,
     $                                               V( 1, p ), 1 )
                                                CALL DAXPY( MVL,
     $                                               CS*SN*APOAQ,
     $                                               V( 1, p ), 1,
     $                                               V( 1, q ), 1 )
                                             END IF
                                          ELSE
                                             CALL DAXPY( M, T*APOAQ,
     $                                                   A( 1, p ), 1,
     $                                                   A( 1, q ), 1 )
                                             CALL DAXPY( M,
     $                                                   -CS*SN*AQOAP,
     $                                                   A( 1, q ), 1,
     $                                                   A( 1, p ), 1 )
                                             WORK( p ) = WORK( p ) / CS
                                             WORK( q ) = WORK( q )*CS
                                             IF( RSVEC ) THEN
                                                CALL DAXPY( MVL,
     $                                               T*APOAQ, V( 1, p ),
     $                                               1, V( 1, q ), 1 )
                                                CALL DAXPY( MVL,
     $                                               -CS*SN*AQOAP,
     $                                               V( 1, q ), 1,
     $                                               V( 1, p ), 1 )
                                             END IF
                                          END IF
                                       END IF
                                    END IF
                                 END IF
*
                              ELSE
                                 IF( AAPP.GT.AAQQ ) THEN
                                    CALL DCOPY( M, A( 1, p ), 1,
     $                                          WORK( N+1 ), 1 )
                                    CALL DLASCL( 'G', 0, 0, AAPP, ONE,
     $                                           M, 1, WORK( N+1 ), LDA,
     $                                           IERR )
                                    CALL DLASCL( 'G', 0, 0, AAQQ, ONE,
     $                                           M, 1, A( 1, q ), LDA,
     $                                           IERR )
                                    TEMP1 = -AAPQ*WORK( p ) / WORK( q )
                                    CALL DAXPY( M, TEMP1, WORK( N+1 ),
     $                                          1, A( 1, q ), 1 )
                                    CALL DLASCL( 'G', 0, 0, ONE, AAQQ,
     $                                           M, 1, A( 1, q ), LDA,
     $                                           IERR )
                                    SVA( q ) = AAQQ*DSQRT( MAX( ZERO,
     $                                         ONE-AAPQ*AAPQ ) )
                                    MXSINJ = MAX( MXSINJ, SFMIN )
                                 ELSE
                                    CALL DCOPY( M, A( 1, q ), 1,
     $                                          WORK( N+1 ), 1 )
                                    CALL DLASCL( 'G', 0, 0, AAQQ, ONE,
     $                                           M, 1, WORK( N+1 ), LDA,
     $                                           IERR )
                                    CALL DLASCL( 'G', 0, 0, AAPP, ONE,
     $                                           M, 1, A( 1, p ), LDA,
     $                                           IERR )
                                    TEMP1 = -AAPQ*WORK( q ) / WORK( p )
                                    CALL DAXPY( M, TEMP1, WORK( N+1 ),
     $                                          1, A( 1, p ), 1 )
                                    CALL DLASCL( 'G', 0, 0, ONE, AAPP,
     $                                           M, 1, A( 1, p ), LDA,
     $                                           IERR )
                                    SVA( p ) = AAPP*DSQRT( MAX( ZERO,
     $                                         ONE-AAPQ*AAPQ ) )
                                    MXSINJ = MAX( MXSINJ, SFMIN )
                                 END IF
                              END IF
*           END IF ROTOK THEN ... ELSE
*
*           In the case of cancellation in updating SVA(q)
*           .. recompute SVA(q)
                              IF( ( SVA( q ) / AAQQ )**2.LE.ROOTEPS )
     $                            THEN
                                 IF( ( AAQQ.LT.ROOTBIG ) .AND.
     $                               ( AAQQ.GT.ROOTSFMIN ) ) THEN
                                    SVA( q ) = DNRM2( M, A( 1, q ), 1 )*
     $                                         WORK( q )
                                 ELSE
                                    T = ZERO
                                    AAQQ = ONE
                                    CALL DLASSQ( M, A( 1, q ), 1, T,
     $                                           AAQQ )
                                    SVA( q ) = T*DSQRT( AAQQ )*WORK( q )
                                 END IF
                              END IF
                              IF( ( AAPP / AAPP0 )**2.LE.ROOTEPS ) THEN
                                 IF( ( AAPP.LT.ROOTBIG ) .AND.
     $                               ( AAPP.GT.ROOTSFMIN ) ) THEN
                                    AAPP = DNRM2( M, A( 1, p ), 1 )*
     $                                     WORK( p )
                                 ELSE
                                    T = ZERO
                                    AAPP = ONE
                                    CALL DLASSQ( M, A( 1, p ), 1, T,
     $                                           AAPP )
                                    AAPP = T*DSQRT( AAPP )*WORK( p )
                                 END IF
                                 SVA( p ) = AAPP
                              END IF
*              end of OK rotation
                           ELSE
                              NOTROT = NOTROT + 1
*[RTD]      SKIPPED  = SKIPPED  + 1
                              PSKIPPED = PSKIPPED + 1
                              IJBLSK = IJBLSK + 1
                           END IF
                        ELSE
                           NOTROT = NOTROT + 1
                           PSKIPPED = PSKIPPED + 1
                           IJBLSK = IJBLSK + 1
                        END IF
*
                        IF( ( i.LE.SWBAND ) .AND. ( IJBLSK.GE.BLSKIP ) )
     $                      THEN
                           SVA( p ) = AAPP
                           NOTROT = 0
                           GO TO 2011
                        END IF
                        IF( ( i.LE.SWBAND ) .AND.
     $                      ( PSKIPPED.GT.ROWSKIP ) ) THEN
                           AAPP = -AAPP
                           NOTROT = 0
                           GO TO 2203
                        END IF
*
 2200                CONTINUE
*        end of the q-loop
 2203                CONTINUE
*
                     SVA( p ) = AAPP
*
                  ELSE
*
                     IF( AAPP.EQ.ZERO )NOTROT = NOTROT +
     $                   MIN( jgl+KBL-1, N ) - jgl + 1
                     IF( AAPP.LT.ZERO )NOTROT = 0
*
                  END IF
*
 2100          CONTINUE
*     end of the p-loop
 2010       CONTINUE
*     end of the jbc-loop
 2011       CONTINUE
*2011 bailed out of the jbc-loop
            DO 2012 p = igl, MIN( igl+KBL-1, N )
               SVA( p ) = DABS( SVA( p ) )
 2012       CONTINUE
***
 2000    CONTINUE
*2000 :: end of the ibr-loop
*
*     .. update SVA(N)
         IF( ( SVA( N ).LT.ROOTBIG ) .AND. ( SVA( N ).GT.ROOTSFMIN ) )
     $       THEN
            SVA( N ) = DNRM2( M, A( 1, N ), 1 )*WORK( N )
         ELSE
            T = ZERO
            AAPP = ONE
            CALL DLASSQ( M, A( 1, N ), 1, T, AAPP )
            SVA( N ) = T*DSQRT( AAPP )*WORK( N )
         END IF
*
*     Additional steering devices
*
         IF( ( i.LT.SWBAND ) .AND. ( ( MXAAPQ.LE.ROOTTOL ) .OR.
     $       ( ISWROT.LE.N ) ) )SWBAND = i
*
         IF( ( i.GT.SWBAND+1 ) .AND. ( MXAAPQ.LT.DSQRT( DBLE( N ) )*
     $       TOL ) .AND. ( DBLE( N )*MXAAPQ*MXSINJ.LT.TOL ) ) THEN
            GO TO 1994
         END IF
*
         IF( NOTROT.GE.EMPTSW )GO TO 1994
*
 1993 CONTINUE
*     end i=1:NSWEEP loop
*
* #:( Reaching this point means that the procedure has not converged.
      INFO = NSWEEP - 1
      GO TO 1995
*
 1994 CONTINUE
* #:) Reaching this point means numerical convergence after the i-th
*     sweep.
*
      INFO = 0
* #:) INFO = 0 confirms successful iterations.
 1995 CONTINUE
*
*     Sort the singular values and find how many are above
*     the underflow threshold.
*
      N2 = 0
      N4 = 0
      DO 5991 p = 1, N - 1
         q = IDAMAX( N-p+1, SVA( p ), 1 ) + p - 1
         IF( p.NE.q ) THEN
            TEMP1 = SVA( p )
            SVA( p ) = SVA( q )
            SVA( q ) = TEMP1
            TEMP1 = WORK( p )
            WORK( p ) = WORK( q )
            WORK( q ) = TEMP1
            CALL DSWAP( M, A( 1, p ), 1, A( 1, q ), 1 )
            IF( RSVEC )CALL DSWAP( MVL, V( 1, p ), 1, V( 1, q ), 1 )
         END IF
         IF( SVA( p ).NE.ZERO ) THEN
            N4 = N4 + 1
            IF( SVA( p )*SKL.GT.SFMIN )N2 = N2 + 1
         END IF
 5991 CONTINUE
      IF( SVA( N ).NE.ZERO ) THEN
         N4 = N4 + 1
         IF( SVA( N )*SKL.GT.SFMIN )N2 = N2 + 1
      END IF
*
*     Normalize the left singular vectors.
*
      IF( LSVEC .OR. UCTOL ) THEN
         DO 1998 p = 1, N2
            CALL DSCAL( M, WORK( p ) / SVA( p ), A( 1, p ), 1 )
 1998    CONTINUE
      END IF
*
*     Scale the product of Jacobi rotations (assemble the fast rotations).
*
      IF( RSVEC ) THEN
         IF( APPLV ) THEN
            DO 2398 p = 1, N
               CALL DSCAL( MVL, WORK( p ), V( 1, p ), 1 )
 2398       CONTINUE
         ELSE
            DO 2399 p = 1, N
               TEMP1 = ONE / DNRM2( MVL, V( 1, p ), 1 )
               CALL DSCAL( MVL, TEMP1, V( 1, p ), 1 )
 2399       CONTINUE
         END IF
      END IF
*
*     Undo scaling, if necessary (and possible).
      IF( ( ( SKL.GT.ONE ) .AND. ( SVA( 1 ).LT.( BIG / SKL) ) )
     $    .OR. ( ( SKL.LT.ONE ) .AND. ( SVA( MAX( N2, 1 ) ) .GT.
     $    ( SFMIN / SKL) ) ) ) THEN
         DO 2400 p = 1, N
            SVA( P ) = SKL*SVA( P )
 2400    CONTINUE
         SKL= ONE
      END IF
*
      WORK( 1 ) = SKL
*     The singular values of A are SKL*SVA(1:N). If SKL.NE.ONE
*     then some of the singular values may overflow or underflow and
*     the spectrum is given in this factored representation.
*
      WORK( 2 ) = DBLE( N4 )
*     N4 is the number of computed nonzero singular values of A.
*
      WORK( 3 ) = DBLE( N2 )
*     N2 is the number of singular values of A greater than SFMIN.
*     If N2<N, SVA(N2:N) contains ZEROS and/or denormalized numbers
*     that may carry some information.
*
      WORK( 4 ) = DBLE( i )
*     i is the index of the last sweep before declaring convergence.
*
      WORK( 5 ) = MXAAPQ
*     MXAAPQ is the largest absolute value of scaled pivots in the
*     last sweep
*
      WORK( 6 ) = MXSINJ
*     MXSINJ is the largest absolute value of the sines of Jacobi angles
*     in the last sweep
*
      RETURN
*     ..
*     .. END OF DGESVJ
*     ..
      END
*> \brief <b> DGESVX computes the solution to system of linear equations A * X = B for GE matrices</b>
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGESVX + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgesvx.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgesvx.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgesvx.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGESVX( FACT, TRANS, N, NRHS, A, LDA, AF, LDAF, IPIV,
*                          EQUED, R, C, B, LDB, X, LDX, RCOND, FERR, BERR,
*                          WORK, IWORK, INFO )
*
*       .. Scalar Arguments ..
*       CHARACTER          EQUED, FACT, TRANS
*       INTEGER            INFO, LDA, LDAF, LDB, LDX, N, NRHS
*       DOUBLE PRECISION   RCOND
*       ..
*       .. Array Arguments ..
*       INTEGER            IPIV( * ), IWORK( * )
*       DOUBLE PRECISION   A( LDA, * ), AF( LDAF, * ), B( LDB, * ),
*      $                   BERR( * ), C( * ), FERR( * ), R( * ),
*      $                   WORK( * ), X( LDX, * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGESVX uses the LU factorization to compute the solution to a real
*> system of linear equations
*>    A * X = B,
*> where A is an N-by-N matrix and X and B are N-by-NRHS matrices.
*>
*> Error bounds on the solution and a condition estimate are also
*> provided.
*> \endverbatim
*
*> \par Description:
*  =================
*>
*> \verbatim
*>
*> The following steps are performed:
*>
*> 1. If FACT = 'E', real scaling factors are computed to equilibrate
*>    the system:
*>       TRANS = 'N':  diag(R)*A*diag(C)     *inv(diag(C))*X = diag(R)*B
*>       TRANS = 'T': (diag(R)*A*diag(C))**T *inv(diag(R))*X = diag(C)*B
*>       TRANS = 'C': (diag(R)*A*diag(C))**H *inv(diag(R))*X = diag(C)*B
*>    Whether or not the system will be equilibrated depends on the
*>    scaling of the matrix A, but if equilibration is used, A is
*>    overwritten by diag(R)*A*diag(C) and B by diag(R)*B (if TRANS='N')
*>    or diag(C)*B (if TRANS = 'T' or 'C').
*>
*> 2. If FACT = 'N' or 'E', the LU decomposition is used to factor the
*>    matrix A (after equilibration if FACT = 'E') as
*>       A = P * L * U,
*>    where P is a permutation matrix, L is a unit lower triangular
*>    matrix, and U is upper triangular.
*>
*> 3. If some U(i,i)=0, so that U is exactly singular, then the routine
*>    returns with INFO = i. Otherwise, the factored form of A is used
*>    to estimate the condition number of the matrix A.  If the
*>    reciprocal of the condition number is less than machine precision,
*>    INFO = N+1 is returned as a warning, but the routine still goes on
*>    to solve for X and compute error bounds as described below.
*>
*> 4. The system of equations is solved for X using the factored form
*>    of A.
*>
*> 5. Iterative refinement is applied to improve the computed solution
*>    matrix and calculate error bounds and backward error estimates
*>    for it.
*>
*> 6. If equilibration was used, the matrix X is premultiplied by
*>    diag(C) (if TRANS = 'N') or diag(R) (if TRANS = 'T' or 'C') so
*>    that it solves the original system before equilibration.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] FACT
*> \verbatim
*>          FACT is CHARACTER*1
*>          Specifies whether or not the factored form of the matrix A is
*>          supplied on entry, and if not, whether the matrix A should be
*>          equilibrated before it is factored.
*>          = 'F':  On entry, AF and IPIV contain the factored form of A.
*>                  If EQUED is not 'N', the matrix A has been
*>                  equilibrated with scaling factors given by R and C.
*>                  A, AF, and IPIV are not modified.
*>          = 'N':  The matrix A will be copied to AF and factored.
*>          = 'E':  The matrix A will be equilibrated if necessary, then
*>                  copied to AF and factored.
*> \endverbatim
*>
*> \param[in] TRANS
*> \verbatim
*>          TRANS is CHARACTER*1
*>          Specifies the form of the system of equations:
*>          = 'N':  A * X = B     (No transpose)
*>          = 'T':  A**T * X = B  (Transpose)
*>          = 'C':  A**H * X = B  (Transpose)
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of linear equations, i.e., the order of the
*>          matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in] NRHS
*> \verbatim
*>          NRHS is INTEGER
*>          The number of right hand sides, i.e., the number of columns
*>          of the matrices B and X.  NRHS >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the N-by-N matrix A.  If FACT = 'F' and EQUED is
*>          not 'N', then A must have been equilibrated by the scaling
*>          factors in R and/or C.  A is not modified if FACT = 'F' or
*>          'N', or if FACT = 'E' and EQUED = 'N' on exit.
*>
*>          On exit, if EQUED .ne. 'N', A is scaled as follows:
*>          EQUED = 'R':  A := diag(R) * A
*>          EQUED = 'C':  A := A * diag(C)
*>          EQUED = 'B':  A := diag(R) * A * diag(C).
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,N).
*> \endverbatim
*>
*> \param[in,out] AF
*> \verbatim
*>          AF is DOUBLE PRECISION array, dimension (LDAF,N)
*>          If FACT = 'F', then AF is an input argument and on entry
*>          contains the factors L and U from the factorization
*>          A = P*L*U as computed by DGETRF.  If EQUED .ne. 'N', then
*>          AF is the factored form of the equilibrated matrix A.
*>
*>          If FACT = 'N', then AF is an output argument and on exit
*>          returns the factors L and U from the factorization A = P*L*U
*>          of the original matrix A.
*>
*>          If FACT = 'E', then AF is an output argument and on exit
*>          returns the factors L and U from the factorization A = P*L*U
*>          of the equilibrated matrix A (see the description of A for
*>          the form of the equilibrated matrix).
*> \endverbatim
*>
*> \param[in] LDAF
*> \verbatim
*>          LDAF is INTEGER
*>          The leading dimension of the array AF.  LDAF >= max(1,N).
*> \endverbatim
*>
*> \param[in,out] IPIV
*> \verbatim
*>          IPIV is INTEGER array, dimension (N)
*>          If FACT = 'F', then IPIV is an input argument and on entry
*>          contains the pivot indices from the factorization A = P*L*U
*>          as computed by DGETRF; row i of the matrix was interchanged
*>          with row IPIV(i).
*>
*>          If FACT = 'N', then IPIV is an output argument and on exit
*>          contains the pivot indices from the factorization A = P*L*U
*>          of the original matrix A.
*>
*>          If FACT = 'E', then IPIV is an output argument and on exit
*>          contains the pivot indices from the factorization A = P*L*U
*>          of the equilibrated matrix A.
*> \endverbatim
*>
*> \param[in,out] EQUED
*> \verbatim
*>          EQUED is CHARACTER*1
*>          Specifies the form of equilibration that was done.
*>          = 'N':  No equilibration (always true if FACT = 'N').
*>          = 'R':  Row equilibration, i.e., A has been premultiplied by
*>                  diag(R).
*>          = 'C':  Column equilibration, i.e., A has been postmultiplied
*>                  by diag(C).
*>          = 'B':  Both row and column equilibration, i.e., A has been
*>                  replaced by diag(R) * A * diag(C).
*>          EQUED is an input argument if FACT = 'F'; otherwise, it is an
*>          output argument.
*> \endverbatim
*>
*> \param[in,out] R
*> \verbatim
*>          R is DOUBLE PRECISION array, dimension (N)
*>          The row scale factors for A.  If EQUED = 'R' or 'B', A is
*>          multiplied on the left by diag(R); if EQUED = 'N' or 'C', R
*>          is not accessed.  R is an input argument if FACT = 'F';
*>          otherwise, R is an output argument.  If FACT = 'F' and
*>          EQUED = 'R' or 'B', each element of R must be positive.
*> \endverbatim
*>
*> \param[in,out] C
*> \verbatim
*>          C is DOUBLE PRECISION array, dimension (N)
*>          The column scale factors for A.  If EQUED = 'C' or 'B', A is
*>          multiplied on the right by diag(C); if EQUED = 'N' or 'R', C
*>          is not accessed.  C is an input argument if FACT = 'F';
*>          otherwise, C is an output argument.  If FACT = 'F' and
*>          EQUED = 'C' or 'B', each element of C must be positive.
*> \endverbatim
*>
*> \param[in,out] B
*> \verbatim
*>          B is DOUBLE PRECISION array, dimension (LDB,NRHS)
*>          On entry, the N-by-NRHS right hand side matrix B.
*>          On exit,
*>          if EQUED = 'N', B is not modified;
*>          if TRANS = 'N' and EQUED = 'R' or 'B', B is overwritten by
*>          diag(R)*B;
*>          if TRANS = 'T' or 'C' and EQUED = 'C' or 'B', B is
*>          overwritten by diag(C)*B.
*> \endverbatim
*>
*> \param[in] LDB
*> \verbatim
*>          LDB is INTEGER
*>          The leading dimension of the array B.  LDB >= max(1,N).
*> \endverbatim
*>
*> \param[out] X
*> \verbatim
*>          X is DOUBLE PRECISION array, dimension (LDX,NRHS)
*>          If INFO = 0 or INFO = N+1, the N-by-NRHS solution matrix X
*>          to the original system of equations.  Note that A and B are
*>          modified on exit if EQUED .ne. 'N', and the solution to the
*>          equilibrated system is inv(diag(C))*X if TRANS = 'N' and
*>          EQUED = 'C' or 'B', or inv(diag(R))*X if TRANS = 'T' or 'C'
*>          and EQUED = 'R' or 'B'.
*> \endverbatim
*>
*> \param[in] LDX
*> \verbatim
*>          LDX is INTEGER
*>          The leading dimension of the array X.  LDX >= max(1,N).
*> \endverbatim
*>
*> \param[out] RCOND
*> \verbatim
*>          RCOND is DOUBLE PRECISION
*>          The estimate of the reciprocal condition number of the matrix
*>          A after equilibration (if done).  If RCOND is less than the
*>          machine precision (in particular, if RCOND = 0), the matrix
*>          is singular to working precision.  This condition is
*>          indicated by a return code of INFO > 0.
*> \endverbatim
*>
*> \param[out] FERR
*> \verbatim
*>          FERR is DOUBLE PRECISION array, dimension (NRHS)
*>          The estimated forward error bound for each solution vector
*>          X(j) (the j-th column of the solution matrix X).
*>          If XTRUE is the true solution corresponding to X(j), FERR(j)
*>          is an estimated upper bound for the magnitude of the largest
*>          element in (X(j) - XTRUE) divided by the magnitude of the
*>          largest element in X(j).  The estimate is as reliable as
*>          the estimate for RCOND, and is almost always a slight
*>          overestimate of the true error.
*> \endverbatim
*>
*> \param[out] BERR
*> \verbatim
*>          BERR is DOUBLE PRECISION array, dimension (NRHS)
*>          The componentwise relative backward error of each solution
*>          vector X(j) (i.e., the smallest relative change in
*>          any element of A or B that makes X(j) an exact solution).
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (4*N)
*>          On exit, WORK(1) contains the reciprocal pivot growth
*>          factor norm(A)/norm(U). The "max absolute element" norm is
*>          used. If WORK(1) is much less than 1, then the stability
*>          of the LU factorization of the (equilibrated) matrix A
*>          could be poor. This also means that the solution X, condition
*>          estimator RCOND, and forward error bound FERR could be
*>          unreliable. If factorization fails with 0<INFO<=N, then
*>          WORK(1) contains the reciprocal pivot growth factor for the
*>          leading INFO columns of A.
*> \endverbatim
*>
*> \param[out] IWORK
*> \verbatim
*>          IWORK is INTEGER array, dimension (N)
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value
*>          > 0:  if INFO = i, and i is
*>                <= N:  U(i,i) is exactly zero.  The factorization has
*>                       been completed, but the factor U is exactly
*>                       singular, so the solution and error bounds
*>                       could not be computed. RCOND = 0 is returned.
*>                = N+1: U is nonsingular, but RCOND is less than machine
*>                       precision, meaning that the matrix is singular
*>                       to working precision.  Nevertheless, the
*>                       solution and error bounds are computed because
*>                       there are a number of situations where the
*>                       computed solution can be more accurate than the
*>                       value of RCOND would suggest.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date April 2012
*
*> \ingroup doubleGEsolve
*
*  =====================================================================
      SUBROUTINE DGESVX( FACT, TRANS, N, NRHS, A, LDA, AF, LDAF, IPIV,
     $                   EQUED, R, C, B, LDB, X, LDX, RCOND, FERR, BERR,
     $                   WORK, IWORK, INFO )
*
*  -- LAPACK driver routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     April 2012
*
*     .. Scalar Arguments ..
      CHARACTER          EQUED, FACT, TRANS
      INTEGER            INFO, LDA, LDAF, LDB, LDX, N, NRHS
      DOUBLE PRECISION   RCOND
*     ..
*     .. Array Arguments ..
      INTEGER            IPIV( * ), IWORK( * )
      DOUBLE PRECISION   A( LDA, * ), AF( LDAF, * ), B( LDB, * ),
     $                   BERR( * ), C( * ), FERR( * ), R( * ),
     $                   WORK( * ), X( LDX, * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ZERO, ONE
      PARAMETER          ( ZERO = 0.0D+0, ONE = 1.0D+0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            COLEQU, EQUIL, NOFACT, NOTRAN, ROWEQU
      CHARACTER          NORM
      INTEGER            I, INFEQU, J
      DOUBLE PRECISION   AMAX, ANORM, BIGNUM, COLCND, RCMAX, RCMIN,
     $                   ROWCND, RPVGRW, SMLNUM
*     ..
*     .. External Functions ..
      LOGICAL            LSAME
      DOUBLE PRECISION   DLAMCH, DLANGE, DLANTR
      EXTERNAL           LSAME, DLAMCH, DLANGE, DLANTR
*     ..
*     .. External Subroutines ..
      EXTERNAL           DGECON, DGEEQU, DGERFS, DGETRF, DGETRS, DLACPY,
     $                   DLAQGE, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, MIN
*     ..
*     .. Executable Statements ..
*
      INFO = 0
      NOFACT = LSAME( FACT, 'N' )
      EQUIL = LSAME( FACT, 'E' )
      NOTRAN = LSAME( TRANS, 'N' )
      IF( NOFACT .OR. EQUIL ) THEN
         EQUED = 'N'
         ROWEQU = .FALSE.
         COLEQU = .FALSE.
      ELSE
         ROWEQU = LSAME( EQUED, 'R' ) .OR. LSAME( EQUED, 'B' )
         COLEQU = LSAME( EQUED, 'C' ) .OR. LSAME( EQUED, 'B' )
         SMLNUM = DLAMCH( 'Safe minimum' )
         BIGNUM = ONE / SMLNUM
      END IF
*
*     Test the input parameters.
*
      IF( .NOT.NOFACT .AND. .NOT.EQUIL .AND. .NOT.LSAME( FACT, 'F' ) )
     $     THEN
         INFO = -1
      ELSE IF( .NOT.NOTRAN .AND. .NOT.LSAME( TRANS, 'T' ) .AND. .NOT.
     $         LSAME( TRANS, 'C' ) ) THEN
         INFO = -2
      ELSE IF( N.LT.0 ) THEN
         INFO = -3
      ELSE IF( NRHS.LT.0 ) THEN
         INFO = -4
      ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
         INFO = -6
      ELSE IF( LDAF.LT.MAX( 1, N ) ) THEN
         INFO = -8
      ELSE IF( LSAME( FACT, 'F' ) .AND. .NOT.
     $         ( ROWEQU .OR. COLEQU .OR. LSAME( EQUED, 'N' ) ) ) THEN
         INFO = -10
      ELSE
         IF( ROWEQU ) THEN
            RCMIN = BIGNUM
            RCMAX = ZERO
            DO 10 J = 1, N
               RCMIN = MIN( RCMIN, R( J ) )
               RCMAX = MAX( RCMAX, R( J ) )
   10       CONTINUE
            IF( RCMIN.LE.ZERO ) THEN
               INFO = -11
            ELSE IF( N.GT.0 ) THEN
               ROWCND = MAX( RCMIN, SMLNUM ) / MIN( RCMAX, BIGNUM )
            ELSE
               ROWCND = ONE
            END IF
         END IF
         IF( COLEQU .AND. INFO.EQ.0 ) THEN
            RCMIN = BIGNUM
            RCMAX = ZERO
            DO 20 J = 1, N
               RCMIN = MIN( RCMIN, C( J ) )
               RCMAX = MAX( RCMAX, C( J ) )
   20       CONTINUE
            IF( RCMIN.LE.ZERO ) THEN
               INFO = -12
            ELSE IF( N.GT.0 ) THEN
               COLCND = MAX( RCMIN, SMLNUM ) / MIN( RCMAX, BIGNUM )
            ELSE
               COLCND = ONE
            END IF
         END IF
         IF( INFO.EQ.0 ) THEN
            IF( LDB.LT.MAX( 1, N ) ) THEN
               INFO = -14
            ELSE IF( LDX.LT.MAX( 1, N ) ) THEN
               INFO = -16
            END IF
         END IF
      END IF
*
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGESVX', -INFO )
         RETURN
      END IF
*
      IF( EQUIL ) THEN
*
*        Compute row and column scalings to equilibrate the matrix A.
*
         CALL DGEEQU( N, N, A, LDA, R, C, ROWCND, COLCND, AMAX, INFEQU )
         IF( INFEQU.EQ.0 ) THEN
*
*           Equilibrate the matrix.
*
            CALL DLAQGE( N, N, A, LDA, R, C, ROWCND, COLCND, AMAX,
     $                   EQUED )
            ROWEQU = LSAME( EQUED, 'R' ) .OR. LSAME( EQUED, 'B' )
            COLEQU = LSAME( EQUED, 'C' ) .OR. LSAME( EQUED, 'B' )
         END IF
      END IF
*
*     Scale the right hand side.
*
      IF( NOTRAN ) THEN
         IF( ROWEQU ) THEN
            DO 40 J = 1, NRHS
               DO 30 I = 1, N
                  B( I, J ) = R( I )*B( I, J )
   30          CONTINUE
   40       CONTINUE
         END IF
      ELSE IF( COLEQU ) THEN
         DO 60 J = 1, NRHS
            DO 50 I = 1, N
               B( I, J ) = C( I )*B( I, J )
   50       CONTINUE
   60    CONTINUE
      END IF
*
      IF( NOFACT .OR. EQUIL ) THEN
*
*        Compute the LU factorization of A.
*
         CALL DLACPY( 'Full', N, N, A, LDA, AF, LDAF )
         CALL DGETRF( N, N, AF, LDAF, IPIV, INFO )
*
*        Return if INFO is non-zero.
*
         IF( INFO.GT.0 ) THEN
*
*           Compute the reciprocal pivot growth factor of the
*           leading rank-deficient INFO columns of A.
*
            RPVGRW = DLANTR( 'M', 'U', 'N', INFO, INFO, AF, LDAF,
     $               WORK )
            IF( RPVGRW.EQ.ZERO ) THEN
               RPVGRW = ONE
            ELSE
               RPVGRW = DLANGE( 'M', N, INFO, A, LDA, WORK ) / RPVGRW
            END IF
            WORK( 1 ) = RPVGRW
            RCOND = ZERO
            RETURN
         END IF
      END IF
*
*     Compute the norm of the matrix A and the
*     reciprocal pivot growth factor RPVGRW.
*
      IF( NOTRAN ) THEN
         NORM = '1'
      ELSE
         NORM = 'I'
      END IF
      ANORM = DLANGE( NORM, N, N, A, LDA, WORK )
      RPVGRW = DLANTR( 'M', 'U', 'N', N, N, AF, LDAF, WORK )
      IF( RPVGRW.EQ.ZERO ) THEN
         RPVGRW = ONE
      ELSE
         RPVGRW = DLANGE( 'M', N, N, A, LDA, WORK ) / RPVGRW
      END IF
*
*     Compute the reciprocal of the condition number of A.
*
      CALL DGECON( NORM, N, AF, LDAF, ANORM, RCOND, WORK, IWORK, INFO )
*
*     Compute the solution matrix X.
*
      CALL DLACPY( 'Full', N, NRHS, B, LDB, X, LDX )
      CALL DGETRS( TRANS, N, NRHS, AF, LDAF, IPIV, X, LDX, INFO )
*
*     Use iterative refinement to improve the computed solution and
*     compute error bounds and backward error estimates for it.
*
      CALL DGERFS( TRANS, N, NRHS, A, LDA, AF, LDAF, IPIV, B, LDB, X,
     $             LDX, FERR, BERR, WORK, IWORK, INFO )
*
*     Transform the solution matrix X to a solution of the original
*     system.
*
      IF( NOTRAN ) THEN
         IF( COLEQU ) THEN
            DO 80 J = 1, NRHS
               DO 70 I = 1, N
                  X( I, J ) = C( I )*X( I, J )
   70          CONTINUE
   80       CONTINUE
            DO 90 J = 1, NRHS
               FERR( J ) = FERR( J ) / COLCND
   90       CONTINUE
         END IF
      ELSE IF( ROWEQU ) THEN
         DO 110 J = 1, NRHS
            DO 100 I = 1, N
               X( I, J ) = R( I )*X( I, J )
  100       CONTINUE
  110    CONTINUE
         DO 120 J = 1, NRHS
            FERR( J ) = FERR( J ) / ROWCND
  120    CONTINUE
      END IF
*
      WORK( 1 ) = RPVGRW
*
*     Set INFO = N+1 if the matrix is singular to working precision.
*
      IF( RCOND.LT.DLAMCH( 'Epsilon' ) )
     $   INFO = N + 1
      RETURN
*
*     End of DGESVX
*
      END
*> \brief \b DGETC2 computes the LU factorization with complete pivoting of the general n-by-n matrix.
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGETC2 + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgetc2.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgetc2.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgetc2.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGETC2( N, A, LDA, IPIV, JPIV, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, LDA, N
*       ..
*       .. Array Arguments ..
*       INTEGER            IPIV( * ), JPIV( * )
*       DOUBLE PRECISION   A( LDA, * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGETC2 computes an LU factorization with complete pivoting of the
*> n-by-n matrix A. The factorization has the form A = P * L * U * Q,
*> where P and Q are permutation matrices, L is lower triangular with
*> unit diagonal elements and U is upper triangular.
*>
*> This is the Level 2 BLAS algorithm.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The order of the matrix A. N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA, N)
*>          On entry, the n-by-n matrix A to be factored.
*>          On exit, the factors L and U from the factorization
*>          A = P*L*U*Q; the unit diagonal elements of L are not stored.
*>          If U(k, k) appears to be less than SMIN, U(k, k) is given the
*>          value of SMIN, i.e., giving a nonsingular perturbed system.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,N).
*> \endverbatim
*>
*> \param[out] IPIV
*> \verbatim
*>          IPIV is INTEGER array, dimension(N).
*>          The pivot indices; for 1 <= i <= N, row i of the
*>          matrix has been interchanged with row IPIV(i).
*> \endverbatim
*>
*> \param[out] JPIV
*> \verbatim
*>          JPIV is INTEGER array, dimension(N).
*>          The pivot indices; for 1 <= j <= N, column j of the
*>          matrix has been interchanged with column JPIV(j).
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>           = 0: successful exit
*>           > 0: if INFO = k, U(k, k) is likely to produce owerflow if
*>                we try to solve for x in Ax = b. So U is perturbed to
*>                avoid the overflow.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date June 2016
*
*> \ingroup doubleGEauxiliary
*
*> \par Contributors:
*  ==================
*>
*>     Bo Kagstrom and Peter Poromaa, Department of Computing Science,
*>     Umea University, S-901 87 Umea, Sweden.
*
*  =====================================================================
      SUBROUTINE DGETC2( N, A, LDA, IPIV, JPIV, INFO )
*
*  -- LAPACK auxiliary routine (version 3.8.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     June 2016
*
*     .. Scalar Arguments ..
      INTEGER            INFO, LDA, N
*     ..
*     .. Array Arguments ..
      INTEGER            IPIV( * ), JPIV( * )
      DOUBLE PRECISION   A( LDA, * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ZERO, ONE
      PARAMETER          ( ZERO = 0.0D+0, ONE = 1.0D+0 )
*     ..
*     .. Local Scalars ..
      INTEGER            I, IP, IPV, J, JP, JPV
      DOUBLE PRECISION   BIGNUM, EPS, SMIN, SMLNUM, XMAX
*     ..
*     .. External Subroutines ..
      EXTERNAL           DGER, DSWAP, DLABAD
*     ..
*     .. External Functions ..
      DOUBLE PRECISION   DLAMCH
      EXTERNAL           DLAMCH
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          ABS, MAX
*     ..
*     .. Executable Statements ..
*
      INFO = 0
*
*     Quick return if possible
*
      IF( N.EQ.0 )
     $   RETURN
*
*     Set constants to control overflow
*
      EPS = DLAMCH( 'P' )
      SMLNUM = DLAMCH( 'S' ) / EPS
      BIGNUM = ONE / SMLNUM
      CALL DLABAD( SMLNUM, BIGNUM )
*
*     Handle the case N=1 by itself
*
      IF( N.EQ.1 ) THEN
         IPIV( 1 ) = 1
         JPIV( 1 ) = 1
         IF( ABS( A( 1, 1 ) ).LT.SMLNUM ) THEN
            INFO = 1
            A( 1, 1 ) = SMLNUM
         END IF
         RETURN
      END IF
*
*     Factorize A using complete pivoting.
*     Set pivots less than SMIN to SMIN.
*
      DO 40 I = 1, N - 1
*
*        Find max element in matrix A
*
         XMAX = ZERO
         DO 20 IP = I, N
            DO 10 JP = I, N
               IF( ABS( A( IP, JP ) ).GE.XMAX ) THEN
                  XMAX = ABS( A( IP, JP ) )
                  IPV = IP
                  JPV = JP
               END IF
   10       CONTINUE
   20    CONTINUE
         IF( I.EQ.1 )
     $      SMIN = MAX( EPS*XMAX, SMLNUM )
*
*        Swap rows
*
         IF( IPV.NE.I )
     $      CALL DSWAP( N, A( IPV, 1 ), LDA, A( I, 1 ), LDA )
         IPIV( I ) = IPV
*
*        Swap columns
*
         IF( JPV.NE.I )
     $      CALL DSWAP( N, A( 1, JPV ), 1, A( 1, I ), 1 )
         JPIV( I ) = JPV
*
*        Check for singularity
*
         IF( ABS( A( I, I ) ).LT.SMIN ) THEN
            INFO = I
            A( I, I ) = SMIN
         END IF
         DO 30 J = I + 1, N
            A( J, I ) = A( J, I ) / A( I, I )
   30    CONTINUE
         CALL DGER( N-I, N-I, -ONE, A( I+1, I ), 1, A( I, I+1 ), LDA,
     $              A( I+1, I+1 ), LDA )
   40 CONTINUE
*
      IF( ABS( A( N, N ) ).LT.SMIN ) THEN
         INFO = N
         A( N, N ) = SMIN
      END IF
*
*     Set last pivots to N
*
      IPIV( N ) = N
      JPIV( N ) = N
*
      RETURN
*
*     End of DGETC2
*
      END
*> \brief \b DGETF2 computes the LU factorization of a general m-by-n matrix using partial pivoting with row interchanges (unblocked algorithm).
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGETF2 + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgetf2.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgetf2.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgetf2.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGETF2( M, N, A, LDA, IPIV, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, LDA, M, N
*       ..
*       .. Array Arguments ..
*       INTEGER            IPIV( * )
*       DOUBLE PRECISION   A( LDA, * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGETF2 computes an LU factorization of a general m-by-n matrix A
*> using partial pivoting with row interchanges.
*>
*> The factorization has the form
*>    A = P * L * U
*> where P is a permutation matrix, L is lower triangular with unit
*> diagonal elements (lower trapezoidal if m > n), and U is upper
*> triangular (upper trapezoidal if m < n).
*>
*> This is the right-looking Level 2 BLAS version of the algorithm.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A.  M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the m by n matrix to be factored.
*>          On exit, the factors L and U from the factorization
*>          A = P*L*U; the unit diagonal elements of L are not stored.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,M).
*> \endverbatim
*>
*> \param[out] IPIV
*> \verbatim
*>          IPIV is INTEGER array, dimension (min(M,N))
*>          The pivot indices; for 1 <= i <= min(M,N), row i of the
*>          matrix was interchanged with row IPIV(i).
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0: successful exit
*>          < 0: if INFO = -k, the k-th argument had an illegal value
*>          > 0: if INFO = k, U(k,k) is exactly zero. The factorization
*>               has been completed, but the factor U is exactly
*>               singular, and division by zero will occur if it is used
*>               to solve a system of equations.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEcomputational
*
*  =====================================================================
      SUBROUTINE DGETF2( M, N, A, LDA, IPIV, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER            INFO, LDA, M, N
*     ..
*     .. Array Arguments ..
      INTEGER            IPIV( * )
      DOUBLE PRECISION   A( LDA, * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ONE, ZERO
      PARAMETER          ( ONE = 1.0D+0, ZERO = 0.0D+0 )
*     ..
*     .. Local Scalars ..
      DOUBLE PRECISION   SFMIN
      INTEGER            I, J, JP
*     ..
*     .. External Functions ..
      DOUBLE PRECISION   DLAMCH
      INTEGER            IDAMAX
      EXTERNAL           DLAMCH, IDAMAX
*     ..
*     .. External Subroutines ..
      EXTERNAL           DGER, DSCAL, DSWAP, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, MIN
*     ..
*     .. Executable Statements ..
*
*     Test the input parameters.
*
      INFO = 0
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -4
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGETF2', -INFO )
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( M.EQ.0 .OR. N.EQ.0 )
     $   RETURN
*
*     Compute machine safe minimum
*
      SFMIN = DLAMCH('S')
*
      DO 10 J = 1, MIN( M, N )
*
*        Find pivot and test for singularity.
*
         JP = J - 1 + IDAMAX( M-J+1, A( J, J ), 1 )
         IPIV( J ) = JP
         IF( A( JP, J ).NE.ZERO ) THEN
*
*           Apply the interchange to columns 1:N.
*
            IF( JP.NE.J )
     $         CALL DSWAP( N, A( J, 1 ), LDA, A( JP, 1 ), LDA )
*
*           Compute elements J+1:M of J-th column.
*
            IF( J.LT.M ) THEN
               IF( ABS(A( J, J )) .GE. SFMIN ) THEN
                  CALL DSCAL( M-J, ONE / A( J, J ), A( J+1, J ), 1 )
               ELSE
                 DO 20 I = 1, M-J
                    A( J+I, J ) = A( J+I, J ) / A( J, J )
   20            CONTINUE
               END IF
            END IF
*
         ELSE IF( INFO.EQ.0 ) THEN
*
            INFO = J
         END IF
*
         IF( J.LT.MIN( M, N ) ) THEN
*
*           Update trailing submatrix.
*
            CALL DGER( M-J, N-J, -ONE, A( J+1, J ), 1, A( J, J+1 ), LDA,
     $                 A( J+1, J+1 ), LDA )
         END IF
   10 CONTINUE
      RETURN
*
*     End of DGETF2
*
      END
*> \brief \b DGETRF
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGETRF + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgetrf.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgetrf.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgetrf.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGETRF( M, N, A, LDA, IPIV, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, LDA, M, N
*       ..
*       .. Array Arguments ..
*       INTEGER            IPIV( * )
*       DOUBLE PRECISION   A( LDA, * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGETRF computes an LU factorization of a general M-by-N matrix A
*> using partial pivoting with row interchanges.
*>
*> The factorization has the form
*>    A = P * L * U
*> where P is a permutation matrix, L is lower triangular with unit
*> diagonal elements (lower trapezoidal if m > n), and U is upper
*> triangular (upper trapezoidal if m < n).
*>
*> This is the right-looking Level 3 BLAS version of the algorithm.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A.  M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the M-by-N matrix to be factored.
*>          On exit, the factors L and U from the factorization
*>          A = P*L*U; the unit diagonal elements of L are not stored.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,M).
*> \endverbatim
*>
*> \param[out] IPIV
*> \verbatim
*>          IPIV is INTEGER array, dimension (min(M,N))
*>          The pivot indices; for 1 <= i <= min(M,N), row i of the
*>          matrix was interchanged with row IPIV(i).
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value
*>          > 0:  if INFO = i, U(i,i) is exactly zero. The factorization
*>                has been completed, but the factor U is exactly
*>                singular, and division by zero will occur if it is used
*>                to solve a system of equations.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEcomputational
*
*  =====================================================================
      SUBROUTINE DGETRF( M, N, A, LDA, IPIV, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER            INFO, LDA, M, N
*     ..
*     .. Array Arguments ..
      INTEGER            IPIV( * )
      DOUBLE PRECISION   A( LDA, * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ONE
      PARAMETER          ( ONE = 1.0D+0 )
*     ..
*     .. Local Scalars ..
      INTEGER            I, IINFO, J, JB, NB
*     ..
*     .. External Subroutines ..
      EXTERNAL           DGEMM, DGETRF2, DLASWP, DTRSM, XERBLA
*     ..
*     .. External Functions ..
      INTEGER            ILAENV
      EXTERNAL           ILAENV
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, MIN
*     ..
*     .. Executable Statements ..
*
*     Test the input parameters.
*
      INFO = 0
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -4
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGETRF', -INFO )
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( M.EQ.0 .OR. N.EQ.0 )
     $   RETURN
*
*     Determine the block size for this environment.
*
      NB = ILAENV( 1, 'DGETRF', ' ', M, N, -1, -1 )
      IF( NB.LE.1 .OR. NB.GE.MIN( M, N ) ) THEN
*
*        Use unblocked code.
*
         CALL DGETRF2( M, N, A, LDA, IPIV, INFO )
      ELSE
*
*        Use blocked code.
*
         DO 20 J = 1, MIN( M, N ), NB
            JB = MIN( MIN( M, N )-J+1, NB )
*
*           Factor diagonal and subdiagonal blocks and test for exact
*           singularity.
*
            CALL DGETRF2( M-J+1, JB, A( J, J ), LDA, IPIV( J ), IINFO )
*
*           Adjust INFO and the pivot indices.
*
            IF( INFO.EQ.0 .AND. IINFO.GT.0 )
     $         INFO = IINFO + J - 1
            DO 10 I = J, MIN( M, J+JB-1 )
               IPIV( I ) = J - 1 + IPIV( I )
   10       CONTINUE
*
*           Apply interchanges to columns 1:J-1.
*
            CALL DLASWP( J-1, A, LDA, J, J+JB-1, IPIV, 1 )
*
            IF( J+JB.LE.N ) THEN
*
*              Apply interchanges to columns J+JB:N.
*
               CALL DLASWP( N-J-JB+1, A( 1, J+JB ), LDA, J, J+JB-1,
     $                      IPIV, 1 )
*
*              Compute block row of U.
*
               CALL DTRSM( 'Left', 'Lower', 'No transpose', 'Unit', JB,
     $                     N-J-JB+1, ONE, A( J, J ), LDA, A( J, J+JB ),
     $                     LDA )
               IF( J+JB.LE.M ) THEN
*
*                 Update trailing submatrix.
*
                  CALL DGEMM( 'No transpose', 'No transpose', M-J-JB+1,
     $                        N-J-JB+1, JB, -ONE, A( J+JB, J ), LDA,
     $                        A( J, J+JB ), LDA, ONE, A( J+JB, J+JB ),
     $                        LDA )
               END IF
            END IF
   20    CONTINUE
      END IF
      RETURN
*
*     End of DGETRF
*
      END
*> \brief \b DGETRF2
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*  Definition:
*  ===========
*
*       RECURSIVE SUBROUTINE DGETRF2( M, N, A, LDA, IPIV, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, LDA, M, N
*       ..
*       .. Array Arguments ..
*       INTEGER            IPIV( * )
*       DOUBLE PRECISION   A( LDA, * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGETRF2 computes an LU factorization of a general M-by-N matrix A
*> using partial pivoting with row interchanges.
*>
*> The factorization has the form
*>    A = P * L * U
*> where P is a permutation matrix, L is lower triangular with unit
*> diagonal elements (lower trapezoidal if m > n), and U is upper
*> triangular (upper trapezoidal if m < n).
*>
*> This is the recursive version of the algorithm. It divides
*> the matrix into four submatrices:
*>
*>        [  A11 | A12  ]  where A11 is n1 by n1 and A22 is n2 by n2
*>    A = [ -----|----- ]  with n1 = min(m,n)/2
*>        [  A21 | A22  ]       n2 = n-n1
*>
*>                                       [ A11 ]
*> The subroutine calls itself to factor [ --- ],
*>                                       [ A12 ]
*>                 [ A12 ]
*> do the swaps on [ --- ], solve A12, update A22,
*>                 [ A22 ]
*>
*> then calls itself to factor A22 and do the swaps on A21.
*>
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A.  M >= 0.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the M-by-N matrix to be factored.
*>          On exit, the factors L and U from the factorization
*>          A = P*L*U; the unit diagonal elements of L are not stored.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,M).
*> \endverbatim
*>
*> \param[out] IPIV
*> \verbatim
*>          IPIV is INTEGER array, dimension (min(M,N))
*>          The pivot indices; for 1 <= i <= min(M,N), row i of the
*>          matrix was interchanged with row IPIV(i).
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value
*>          > 0:  if INFO = i, U(i,i) is exactly zero. The factorization
*>                has been completed, but the factor U is exactly
*>                singular, and division by zero will occur if it is used
*>                to solve a system of equations.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date June 2016
*
*> \ingroup doubleGEcomputational
*
*  =====================================================================
      RECURSIVE SUBROUTINE DGETRF2( M, N, A, LDA, IPIV, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     June 2016
*
*     .. Scalar Arguments ..
      INTEGER            INFO, LDA, M, N
*     ..
*     .. Array Arguments ..
      INTEGER            IPIV( * )
      DOUBLE PRECISION   A( LDA, * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ONE, ZERO
      PARAMETER          ( ONE = 1.0D+0, ZERO = 0.0D+0 )
*     ..
*     .. Local Scalars ..
      DOUBLE PRECISION   SFMIN, TEMP
      INTEGER            I, IINFO, N1, N2
*     ..
*     .. External Functions ..
      DOUBLE PRECISION   DLAMCH
      INTEGER            IDAMAX
      EXTERNAL           DLAMCH, IDAMAX
*     ..
*     .. External Subroutines ..
      EXTERNAL           DGEMM, DSCAL, DLASWP, DTRSM, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, MIN
*     ..
*     .. Executable Statements ..
*
*     Test the input parameters
*
      INFO = 0
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -4
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGETRF2', -INFO )
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( M.EQ.0 .OR. N.EQ.0 )
     $   RETURN

      IF ( M.EQ.1 ) THEN
*
*        Use unblocked code for one row case
*        Just need to handle IPIV and INFO
*
         IPIV( 1 ) = 1
         IF ( A(1,1).EQ.ZERO )
     $      INFO = 1
*
      ELSE IF( N.EQ.1 ) THEN
*
*        Use unblocked code for one column case
*
*
*        Compute machine safe minimum
*
         SFMIN = DLAMCH('S')
*
*        Find pivot and test for singularity
*
         I = IDAMAX( M, A( 1, 1 ), 1 )
         IPIV( 1 ) = I
         IF( A( I, 1 ).NE.ZERO ) THEN
*
*           Apply the interchange
*
            IF( I.NE.1 ) THEN
               TEMP = A( 1, 1 )
               A( 1, 1 ) = A( I, 1 )
               A( I, 1 ) = TEMP
            END IF
*
*           Compute elements 2:M of the column
*
            IF( ABS(A( 1, 1 )) .GE. SFMIN ) THEN
               CALL DSCAL( M-1, ONE / A( 1, 1 ), A( 2, 1 ), 1 )
            ELSE
               DO 10 I = 1, M-1
                  A( 1+I, 1 ) = A( 1+I, 1 ) / A( 1, 1 )
   10          CONTINUE
            END IF
*
         ELSE
            INFO = 1
         END IF
*
      ELSE
*
*        Use recursive code
*
         N1 = MIN( M, N ) / 2
         N2 = N-N1
*
*               [ A11 ]
*        Factor [ --- ]
*               [ A21 ]
*
         CALL DGETRF2( M, N1, A, LDA, IPIV, IINFO )

         IF ( INFO.EQ.0 .AND. IINFO.GT.0 )
     $      INFO = IINFO
*
*                              [ A12 ]
*        Apply interchanges to [ --- ]
*                              [ A22 ]
*
         CALL DLASWP( N2, A( 1, N1+1 ), LDA, 1, N1, IPIV, 1 )
*
*        Solve A12
*
         CALL DTRSM( 'L', 'L', 'N', 'U', N1, N2, ONE, A, LDA,
     $               A( 1, N1+1 ), LDA )
*
*        Update A22
*
         CALL DGEMM( 'N', 'N', M-N1, N2, N1, -ONE, A( N1+1, 1 ), LDA,
     $               A( 1, N1+1 ), LDA, ONE, A( N1+1, N1+1 ), LDA )
*
*        Factor A22
*
         CALL DGETRF2( M-N1, N2, A( N1+1, N1+1 ), LDA, IPIV( N1+1 ),
     $                 IINFO )
*
*        Adjust INFO and the pivot indices
*
         IF ( INFO.EQ.0 .AND. IINFO.GT.0 )
     $      INFO = IINFO + N1
         DO 20 I = N1+1, MIN( M, N )
            IPIV( I ) = IPIV( I ) + N1
   20    CONTINUE
*
*        Apply interchanges to A21
*
         CALL DLASWP( N1, A( 1, 1 ), LDA, N1+1, MIN( M, N), IPIV, 1 )
*
      END IF
      RETURN
*
*     End of DGETRF2
*
      END
*> \brief \b DGETRI
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGETRI + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgetri.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgetri.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgetri.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGETRI( N, A, LDA, IPIV, WORK, LWORK, INFO )
*
*       .. Scalar Arguments ..
*       INTEGER            INFO, LDA, LWORK, N
*       ..
*       .. Array Arguments ..
*       INTEGER            IPIV( * )
*       DOUBLE PRECISION   A( LDA, * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGETRI computes the inverse of a matrix using the LU factorization
*> computed by DGETRF.
*>
*> This method inverts U and then computes inv(A) by solving the system
*> inv(A)*L = inv(U) for inv(A).
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The order of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the factors L and U from the factorization
*>          A = P*L*U as computed by DGETRF.
*>          On exit, if INFO = 0, the inverse of the original matrix A.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,N).
*> \endverbatim
*>
*> \param[in] IPIV
*> \verbatim
*>          IPIV is INTEGER array, dimension (N)
*>          The pivot indices from DGETRF; for 1<=i<=N, row i of the
*>          matrix was interchanged with row IPIV(i).
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*>          WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK))
*>          On exit, if INFO=0, then WORK(1) returns the optimal LWORK.
*> \endverbatim
*>
*> \param[in] LWORK
*> \verbatim
*>          LWORK is INTEGER
*>          The dimension of the array WORK.  LWORK >= max(1,N).
*>          For optimal performance LWORK >= N*NB, where NB is
*>          the optimal blocksize returned by ILAENV.
*>
*>          If LWORK = -1, then a workspace query is assumed; the routine
*>          only calculates the optimal size of the WORK array, returns
*>          this value as the first entry of the WORK array, and no error
*>          message related to LWORK is issued by XERBLA.
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value
*>          > 0:  if INFO = i, U(i,i) is exactly zero; the matrix is
*>                singular and its inverse could not be computed.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEcomputational
*
*  =====================================================================
      SUBROUTINE DGETRI( N, A, LDA, IPIV, WORK, LWORK, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER            INFO, LDA, LWORK, N
*     ..
*     .. Array Arguments ..
      INTEGER            IPIV( * )
      DOUBLE PRECISION   A( LDA, * ), WORK( * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ZERO, ONE
      PARAMETER          ( ZERO = 0.0D+0, ONE = 1.0D+0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            LQUERY
      INTEGER            I, IWS, J, JB, JJ, JP, LDWORK, LWKOPT, NB,
     $                   NBMIN, NN
*     ..
*     .. External Functions ..
      INTEGER            ILAENV
      EXTERNAL           ILAENV
*     ..
*     .. External Subroutines ..
      EXTERNAL           DGEMM, DGEMV, DSWAP, DTRSM, DTRTRI, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, MIN
*     ..
*     .. Executable Statements ..
*
*     Test the input parameters.
*
      INFO = 0
      NB = ILAENV( 1, 'DGETRI', ' ', N, -1, -1, -1 )
      LWKOPT = N*NB
      WORK( 1 ) = LWKOPT
      LQUERY = ( LWORK.EQ.-1 )
      IF( N.LT.0 ) THEN
         INFO = -1
      ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
         INFO = -3
      ELSE IF( LWORK.LT.MAX( 1, N ) .AND. .NOT.LQUERY ) THEN
         INFO = -6
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGETRI', -INFO )
         RETURN
      ELSE IF( LQUERY ) THEN
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( N.EQ.0 )
     $   RETURN
*
*     Form inv(U).  If INFO > 0 from DTRTRI, then U is singular,
*     and the inverse is not computed.
*
      CALL DTRTRI( 'Upper', 'Non-unit', N, A, LDA, INFO )
      IF( INFO.GT.0 )
     $   RETURN
*
      NBMIN = 2
      LDWORK = N
      IF( NB.GT.1 .AND. NB.LT.N ) THEN
         IWS = MAX( LDWORK*NB, 1 )
         IF( LWORK.LT.IWS ) THEN
            NB = LWORK / LDWORK
            NBMIN = MAX( 2, ILAENV( 2, 'DGETRI', ' ', N, -1, -1, -1 ) )
         END IF
      ELSE
         IWS = N
      END IF
*
*     Solve the equation inv(A)*L = inv(U) for inv(A).
*
      IF( NB.LT.NBMIN .OR. NB.GE.N ) THEN
*
*        Use unblocked code.
*
         DO 20 J = N, 1, -1
*
*           Copy current column of L to WORK and replace with zeros.
*
            DO 10 I = J + 1, N
               WORK( I ) = A( I, J )
               A( I, J ) = ZERO
   10       CONTINUE
*
*           Compute current column of inv(A).
*
            IF( J.LT.N )
     $         CALL DGEMV( 'No transpose', N, N-J, -ONE, A( 1, J+1 ),
     $                     LDA, WORK( J+1 ), 1, ONE, A( 1, J ), 1 )
   20    CONTINUE
      ELSE
*
*        Use blocked code.
*
         NN = ( ( N-1 ) / NB )*NB + 1
         DO 50 J = NN, 1, -NB
            JB = MIN( NB, N-J+1 )
*
*           Copy current block column of L to WORK and replace with
*           zeros.
*
            DO 40 JJ = J, J + JB - 1
               DO 30 I = JJ + 1, N
                  WORK( I+( JJ-J )*LDWORK ) = A( I, JJ )
                  A( I, JJ ) = ZERO
   30          CONTINUE
   40       CONTINUE
*
*           Compute current block column of inv(A).
*
            IF( J+JB.LE.N )
     $         CALL DGEMM( 'No transpose', 'No transpose', N, JB,
     $                     N-J-JB+1, -ONE, A( 1, J+JB ), LDA,
     $                     WORK( J+JB ), LDWORK, ONE, A( 1, J ), LDA )
            CALL DTRSM( 'Right', 'Lower', 'No transpose', 'Unit', N, JB,
     $                  ONE, WORK( J ), LDWORK, A( 1, J ), LDA )
   50    CONTINUE
      END IF
*
*     Apply column interchanges.
*
      DO 60 J = N - 1, 1, -1
         JP = IPIV( J )
         IF( JP.NE.J )
     $      CALL DSWAP( N, A( 1, J ), 1, A( 1, JP ), 1 )
   60 CONTINUE
*
      WORK( 1 ) = IWS
      RETURN
*
*     End of DGETRI
*
      END
*> \brief \b DGETRS
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGETRS + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgetrs.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgetrs.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgetrs.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGETRS( TRANS, N, NRHS, A, LDA, IPIV, B, LDB, INFO )
*
*       .. Scalar Arguments ..
*       CHARACTER          TRANS
*       INTEGER            INFO, LDA, LDB, N, NRHS
*       ..
*       .. Array Arguments ..
*       INTEGER            IPIV( * )
*       DOUBLE PRECISION   A( LDA, * ), B( LDB, * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGETRS solves a system of linear equations
*>    A * X = B  or  A**T * X = B
*> with a general N-by-N matrix A using the LU factorization computed
*> by DGETRF.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] TRANS
*> \verbatim
*>          TRANS is CHARACTER*1
*>          Specifies the form of the system of equations:
*>          = 'N':  A * X = B  (No transpose)
*>          = 'T':  A**T* X = B  (Transpose)
*>          = 'C':  A**T* X = B  (Conjugate transpose = Transpose)
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The order of the matrix A.  N >= 0.
*> \endverbatim
*>
*> \param[in] NRHS
*> \verbatim
*>          NRHS is INTEGER
*>          The number of right hand sides, i.e., the number of columns
*>          of the matrix B.  NRHS >= 0.
*> \endverbatim
*>
*> \param[in] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          The factors L and U from the factorization A = P*L*U
*>          as computed by DGETRF.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A.  LDA >= max(1,N).
*> \endverbatim
*>
*> \param[in] IPIV
*> \verbatim
*>          IPIV is INTEGER array, dimension (N)
*>          The pivot indices from DGETRF; for 1<=i<=N, row i of the
*>          matrix was interchanged with row IPIV(i).
*> \endverbatim
*>
*> \param[in,out] B
*> \verbatim
*>          B is DOUBLE PRECISION array, dimension (LDB,NRHS)
*>          On entry, the right hand side matrix B.
*>          On exit, the solution matrix X.
*> \endverbatim
*>
*> \param[in] LDB
*> \verbatim
*>          LDB is INTEGER
*>          The leading dimension of the array B.  LDB >= max(1,N).
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit
*>          < 0:  if INFO = -i, the i-th argument had an illegal value
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGEcomputational
*
*  =====================================================================
      SUBROUTINE DGETRS( TRANS, N, NRHS, A, LDA, IPIV, B, LDB, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      CHARACTER          TRANS
      INTEGER            INFO, LDA, LDB, N, NRHS
*     ..
*     .. Array Arguments ..
      INTEGER            IPIV( * )
      DOUBLE PRECISION   A( LDA, * ), B( LDB, * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ONE
      PARAMETER          ( ONE = 1.0D+0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            NOTRAN
*     ..
*     .. External Functions ..
      LOGICAL            LSAME
      EXTERNAL           LSAME
*     ..
*     .. External Subroutines ..
      EXTERNAL           DLASWP, DTRSM, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX
*     ..
*     .. Executable Statements ..
*
*     Test the input parameters.
*
      INFO = 0
      NOTRAN = LSAME( TRANS, 'N' )
      IF( .NOT.NOTRAN .AND. .NOT.LSAME( TRANS, 'T' ) .AND. .NOT.
     $    LSAME( TRANS, 'C' ) ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( NRHS.LT.0 ) THEN
         INFO = -3
      ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
         INFO = -5
      ELSE IF( LDB.LT.MAX( 1, N ) ) THEN
         INFO = -8
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGETRS', -INFO )
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( N.EQ.0 .OR. NRHS.EQ.0 )
     $   RETURN
*
      IF( NOTRAN ) THEN
*
*        Solve A * X = B.
*
*        Apply row interchanges to the right hand sides.
*
         CALL DLASWP( NRHS, B, LDB, 1, N, IPIV, 1 )
*
*        Solve L*X = B, overwriting B with X.
*
         CALL DTRSM( 'Left', 'Lower', 'No transpose', 'Unit', N, NRHS,
     $               ONE, A, LDA, B, LDB )
*
*        Solve U*X = B, overwriting B with X.
*
         CALL DTRSM( 'Left', 'Upper', 'No transpose', 'Non-unit', N,
     $               NRHS, ONE, A, LDA, B, LDB )
      ELSE
*
*        Solve A**T * X = B.
*
*        Solve U**T *X = B, overwriting B with X.
*
         CALL DTRSM( 'Left', 'Upper', 'Transpose', 'Non-unit', N, NRHS,
     $               ONE, A, LDA, B, LDB )
*
*        Solve L**T *X = B, overwriting B with X.
*
         CALL DTRSM( 'Left', 'Lower', 'Transpose', 'Unit', N, NRHS, ONE,
     $               A, LDA, B, LDB )
*
*        Apply row interchanges to the solution vectors.
*
         CALL DLASWP( NRHS, B, LDB, 1, N, IPIV, -1 )
      END IF
*
      RETURN
*
*     End of DGETRS
*
      END
*> \brief \b DGGBAK
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGGBAK + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dggbak.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dggbak.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dggbak.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGGBAK( JOB, SIDE, N, ILO, IHI, LSCALE, RSCALE, M, V,
*                          LDV, INFO )
*
*       .. Scalar Arguments ..
*       CHARACTER          JOB, SIDE
*       INTEGER            IHI, ILO, INFO, LDV, M, N
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   LSCALE( * ), RSCALE( * ), V( LDV, * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGGBAK forms the right or left eigenvectors of a real generalized
*> eigenvalue problem A*x = lambda*B*x, by backward transformation on
*> the computed eigenvectors of the balanced pair of matrices output by
*> DGGBAL.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] JOB
*> \verbatim
*>          JOB is CHARACTER*1
*>          Specifies the type of backward transformation required:
*>          = 'N':  do nothing, return immediately;
*>          = 'P':  do backward transformation for permutation only;
*>          = 'S':  do backward transformation for scaling only;
*>          = 'B':  do backward transformations for both permutation and
*>                  scaling.
*>          JOB must be the same as the argument JOB supplied to DGGBAL.
*> \endverbatim
*>
*> \param[in] SIDE
*> \verbatim
*>          SIDE is CHARACTER*1
*>          = 'R':  V contains right eigenvectors;
*>          = 'L':  V contains left eigenvectors.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of rows of the matrix V.  N >= 0.
*> \endverbatim
*>
*> \param[in] ILO
*> \verbatim
*>          ILO is INTEGER
*> \endverbatim
*>
*> \param[in] IHI
*> \verbatim
*>          IHI is INTEGER
*>          The integers ILO and IHI determined by DGGBAL.
*>          1 <= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0.
*> \endverbatim
*>
*> \param[in] LSCALE
*> \verbatim
*>          LSCALE is DOUBLE PRECISION array, dimension (N)
*>          Details of the permutations and/or scaling factors applied
*>          to the left side of A and B, as returned by DGGBAL.
*> \endverbatim
*>
*> \param[in] RSCALE
*> \verbatim
*>          RSCALE is DOUBLE PRECISION array, dimension (N)
*>          Details of the permutations and/or scaling factors applied
*>          to the right side of A and B, as returned by DGGBAL.
*> \endverbatim
*>
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of columns of the matrix V.  M >= 0.
*> \endverbatim
*>
*> \param[in,out] V
*> \verbatim
*>          V is DOUBLE PRECISION array, dimension (LDV,M)
*>          On entry, the matrix of right or left eigenvectors to be
*>          transformed, as returned by DTGEVC.
*>          On exit, V is overwritten by the transformed eigenvectors.
*> \endverbatim
*>
*> \param[in] LDV
*> \verbatim
*>          LDV is INTEGER
*>          The leading dimension of the matrix V. LDV >= max(1,N).
*> \endverbatim
*>
*> \param[out] INFO
*> \verbatim
*>          INFO is INTEGER
*>          = 0:  successful exit.
*>          < 0:  if INFO = -i, the i-th argument had an illegal value.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup doubleGBcomputational
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>  See R.C. Ward, Balancing the generalized eigenvalue problem,
*>                 SIAM J. Sci. Stat. Comp. 2 (1981), 141-152.
*> \endverbatim
*>
*  =====================================================================
      SUBROUTINE DGGBAK( JOB, SIDE, N, ILO, IHI, LSCALE, RSCALE, M, V,
     $                   LDV, INFO )
*
*  -- LAPACK computational routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      CHARACTER          JOB, SIDE
      INTEGER            IHI, ILO, INFO, LDV, M, N
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   LSCALE( * ), RSCALE( * ), V( LDV, * )
*     ..
*
*  =====================================================================
*
*     .. Local Scalars ..
      LOGICAL            LEFTV, RIGHTV
      INTEGER            I, K
*     ..
*     .. External Functions ..
      LOGICAL            LSAME
      EXTERNAL           LSAME
*     ..
*     .. External Subroutines ..
      EXTERNAL           DSCAL, DSWAP, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX, INT
*     ..
*     .. Executable Statements ..
*
*     Test the input parameters
*
      RIGHTV = LSAME( SIDE, 'R' )
      LEFTV = LSAME( SIDE, 'L' )
*
      INFO = 0
      IF( .NOT.LSAME( JOB, 'N' ) .AND. .NOT.LSAME( JOB, 'P' ) .AND.
     $    .NOT.LSAME( JOB, 'S' ) .AND. .NOT.LSAME( JOB, 'B' ) ) THEN
         INFO = -1
      ELSE IF( .NOT.RIGHTV .AND. .NOT.LEFTV ) THEN
         INFO = -2
      ELSE IF( N.LT.0 ) THEN
         INFO = -3
      ELSE IF( ILO.LT.1 ) THEN
         INFO = -4
      ELSE IF( N.EQ.0 .AND. IHI.EQ.0 .AND. ILO.NE.1 ) THEN
         INFO = -4
      ELSE IF( N.GT.0 .AND. ( IHI.LT.ILO .OR. IHI.GT.MAX( 1, N ) ) )
     $   THEN
         INFO = -5
      ELSE IF( N.EQ.0 .AND. ILO.EQ.1 .AND. IHI.NE.0 ) THEN
         INFO = -5
      ELSE IF( M.LT.0 ) THEN
         INFO = -8
      ELSE IF( LDV.LT.MAX( 1, N ) ) THEN
         INFO = -10
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DGGBAK', -INFO )
         RETURN
      END IF
*
*     Quick return if possible
*
      IF( N.EQ.0 )
     $   RETURN
      IF( M.EQ.0 )
     $   RETURN
      IF( LSAME( JOB, 'N' ) )
     $   RETURN
*
      IF( ILO.EQ.IHI )
     $   GO TO 30
*
*     Backward balance
*
      IF( LSAME( JOB, 'S' ) .OR. LSAME( JOB, 'B' ) ) THEN
*
*        Backward transformation on right eigenvectors
*
         IF( RIGHTV ) THEN
            DO 10 I = ILO, IHI
               CALL DSCAL( M, RSCALE( I ), V( I, 1 ), LDV )
   10       CONTINUE
         END IF
*
*        Backward transformation on left eigenvectors
*
         IF( LEFTV ) THEN
            DO 20 I = ILO, IHI
               CALL DSCAL( M, LSCALE( I ), V( I, 1 ), LDV )
   20       CONTINUE
         END IF
      END IF
*
*     Backward permutation
*
   30 CONTINUE
      IF( LSAME( JOB, 'P' ) .OR. LSAME( JOB, 'B' ) ) THEN
*
*        Backward permutation on right eigenvectors
*
         IF( RIGHTV ) THEN
            IF( ILO.EQ.1 )
     $         GO TO 50
*
            DO 40 I = ILO - 1, 1, -1
               K = INT(RSCALE( I ))
               IF( K.EQ.I )
     $            GO TO 40
               CALL DSWAP( M, V( I, 1 ), LDV, V( K, 1 ), LDV )
   40       CONTINUE
*
   50       CONTINUE
            IF( IHI.EQ.N )
     $         GO TO 70
            DO 60 I = IHI + 1, N
               K = INT(RSCALE( I ))
               IF( K.EQ.I )
     $            GO TO 60
               CALL DSWAP( M, V( I, 1 ), LDV, V( K, 1 ), LDV )
   60       CONTINUE
         END IF
*
*        Backward permutation on left eigenvectors
*
   70    CONTINUE
         IF( LEFTV ) THEN
            IF( ILO.EQ.1 )
     $         GO TO 90
            DO 80 I = ILO - 1, 1, -1
               K = INT(LSCALE( I ))
               IF( K.EQ.I )
     $            GO TO 80
               CALL DSWAP( M, V( I, 1 ), LDV, V( K, 1 ), LDV )
   80       CONTINUE
*
   90       CONTINUE
            IF( IHI.EQ.N )
     $         GO TO 110
            DO 100 I = IHI + 1, N
               K = INT(LSCALE( I ))
               IF( K.EQ.I )
     $            GO TO 100
               CALL DSWAP( M, V( I, 1 ), LDV, V( K, 1 ), LDV )
  100       CONTINUE
         END IF
      END IF
*
  110 CONTINUE
*
      RETURN
*
*     End of DGGBAK
*
      END
*> \brief \b DGGBAL
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DGGBAL + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dggbal.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dggbal.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dggbal.f">
*> [TXT]</a>
*> \endhtmlonly
*
*  Definition:
*  ===========
*
*       SUBROUTINE DGGBAL( JOB, N, A, LDA, B, LDB, ILO, IHI, LSCALE,
*                          RSCALE, WORK, INFO )
*
*       .. Scalar Arguments ..
*       CHARACTER          JOB
*       INTEGER            IHI, ILO, INFO, LDA, LDB, N
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION   A( LDA, * ), B( LDB, * ), LSCALE( * ),
*      $                   RSCALE( * ), WORK( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DGGBAL balances a pair of general real matrices (A,B).  This
*> involves, first, permuting A and B by similarity transformations to
*> isolate eigenvalues in the first 1 to ILO$-$1 and last IHI+1 to N
*> elements on the diagonal; and second, applying a diagonal similarity
*> transformation to rows and columns ILO to IHI to make the rows
*> and columns as close in norm as possible. Both steps are optional.
*>
*> Balancing may reduce the 1-norm of the matrices, and improve the
*> accuracy of the computed eigenvalues and/or eigenvectors in the
*> generalized eigenvalue problem A*x = lambda*B*x.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] JOB
*> \verbatim
*>          JOB is CHARACTER*1
*>          Specifies the operations to be performed on A and B:
*>          = 'N':  none:  simply set ILO = 1, IHI = N, LSCALE(I) = 1.0
*>                  and RSCALE(I) = 1.0 for i = 1,...,N.
*>          = 'P':  permute only;
*>          = 'S':  scale only;
*>          = 'B':  both permute and scale.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The order of the matrices A and B.  N >= 0.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is DOUBLE PRECISION array, dimension (LDA,N)
*>          On entry, the input matrix A.
*>          On exit,  A is overwritten by the balanced matrix.
*>          If JOB = 'N', A is not referenced.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A. LDA >= max(1,N).
*> \endverbatim
*>
*> \param[in,out] B
*> \verbatim
*>          B is DOUBLE PRECISION array, dimension (LDB,N)
*>          On entry, the input matrix B.
*>          On exit,  B is overwritten by the balanced matrix.
*>          If JOB = 'N', B is not referenced.
*> \endverbatim
*>
*> \param[in] LDB
*> \verbatim
*>          LDB is INTEGER
*>          The leading dimension of the array B. LDB >= max(1,N).
*> \endverbatim
*>
*> \param[out] ILO
*> \verbatim
*>          ILO is INTEGER
*> \endverbatim
*>
*> \param[out] IHI