function r8pbl_print_some ( n, mu, a, ilo, jlo, ihi, jhi, title ) %*****************************************************************************80 % %% R8PBL_PRINT_SOME prints some of a R8PBL matrix. % % Discussion: % % The R8PBL storage format is for a symmetric positive definite band matrix. % % To save storage, only the diagonal and lower triangle of A is stored, % in a compact diagonal format that preserves columns. % % The diagonal is stored in row 1 of the array. % The first subdiagonal in row 2, columns 1 through MU. % The second subdiagonal in row 3, columns 1 through MU-1. % The MU-th subdiagonal in row MU+1, columns 1 through 1. % % Licensing: % % This code is distributed under the GNU LGPL license. % % Modified: % % 07 April 2006 % % Author: % % John Burkardt % % Parameters: % % Input, integer N, the order of the matrix. % N must be positive. % % Input, integer MU, the upper (and lower) bandwidth. % MU must be nonnegative, and no greater than N-1. % % Input, real A(MU+1,N), the R8PBL matrix. % % Input, integer ILO, JLO, IHI, JHI, the first row and % column, and the last row and column to be printed. % % Input, string TITLE, a title. % fprintf ( 1, '\n' ); fprintf ( 1, '%s\n', title ); incx = 5; % % Print the columns of the matrix, in strips of 5. % for j2lo = jlo : incx : jhi j2hi = j2lo + incx - 1; j2hi = min ( j2hi, n ); j2hi = min ( j2hi, jhi ); inc = j2hi + 1 - j2lo; fprintf ( 1, '\n' ); fprintf ( 1, ' Col: ' ); for j = j2lo : j2hi fprintf ( 1, '%7d ', j ); end fprintf ( 1, '\n' ); fprintf ( 1, ' Row\n' ); fprintf ( 1, ' ---\n' ); % % Determine the range of the rows in this strip. % i2lo = max ( ilo, 1 ); i2lo = max ( i2lo, j2lo - mu ); i2hi = min ( ihi, n ); i2hi = min ( i2hi, j2hi + mu ); for i = i2lo : i2hi fprintf ( 1, '%4d ', i ); % % Print out (up to) 5 entries in row I, that lie in the current strip. % for j2 = 1 : inc j = j2lo - 1 + j2; if ( i <= j & j <= i + mu ) aij = a(j-i+1,i); elseif ( j <= i & i <= j + mu ) aij = a(i-j+1,j); else aij = 0.0E+00; end if ( mu < i-j | mu < j-i ) fprintf ( 1, ' ' ); else fprintf ( 1, '%12f ', aij ); end end fprintf ( 1, '\n' ); end end fprintf ( 1, '\n' ); return end