function [ n_data, x, fx ] = cbrt_values ( n_data )

%*****************************************************************************80
%
%% CBRT_VALUES returns some values of the cube root function.
%
%  Discussion:
%
%    CBRT(X) = real number Y such that Y * Y * Y = X.
%
%    In Mathematica, the function can be evaluated by:
%
%      Sign[x] * ( Abs[x] )^(1/3)
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    22 June 2007
%
%  Author:
%
%    John Burkardt
%
%  Reference:
%
%    Milton Abramowitz, Irene Stegun,
%    Handbook of Mathematical Functions,
%    National Bureau of Standards, 1964,
%    ISBN: 0-486-61272-4,
%    LC: QA47.A34.
%
%    Stephen Wolfram,
%    The Mathematica Book,
%    Fourth Edition,
%    Cambridge University Press, 1999,
%    ISBN: 0-521-64314-7,
%    LC: QA76.95.W65.
%
%  Parameters:
%
%    Input/output, integer N_DATA.  The user sets N_DATA to 0 before the
%    first call.  On each call, the routine increments N_DATA by 1, and
%    returns the corresponding data; when there is no more data, the
%    output value of N_DATA will be 0 again.
%
%    Output, real X, the argument of the function.
%
%    Output real FX, the value of the function.
%
  n_max = 14;

  fx_vec = [ ...
    0.0000000000000000E+00, ...
   -0.0020082988563383484484E+00, ...
    0.44814047465571647087E+00, ...
   -0.46415888336127788924E+00, ...
    0.73680629972807732116E+00, ...
   -1.0000000000000000000E+00, ...
    1.2599210498948731648E+00, ...
   -1.4422495703074083823E+00, ...
    1.4645918875615232630E+00, ...
   -2.6684016487219448673E+00, ...
    3.0723168256858472933E+00, ...
   -4.1408177494228532500E+00, ...
    4.5947008922070398061E+00, ...
   -497.93385921817447440E+00 ];

  x_vec = [ ...
     0.0000000000000000E+00, ...
    -0.8100000073710001E-08, ...
     0.9000000000000000E-01, ...
    -0.1000000000000000E+00, ...
     0.4000000000000000E+00, ...
    -0.1000000000000000E+01, ... 
     0.2000000000000000E+01, ...
    -0.3000000000000000E+01, ...
     0.3141592653589793E+01, ...
    -0.1900000000000000E+02, ...
     0.2900000000000000E+02, ...
    -0.7100000000000000E+02, ...
     0.9700000000000000E+02, ...
    -0.1234567890000000E+09 ];

  if ( n_data < 0 )
    n_data = 0;
  end

  n_data = n_data + 1;

  if ( n_max < n_data )
    n_data = 0;
    x = 0.0;
    fx = 0.0;
  else
    x = x_vec(n_data);
    fx = fx_vec(n_data);
  end

  return
end