function [ n_data, x, fx ] = exp3_int_values ( n_data )

%*****************************************************************************80
%
%% EXP3_INT_VALUES returns some values of the EXP3 integral function.
%
%  Discussion:
%
%    The function is defined by:
%
%      EXP3_INT(x) = Integral ( 0 <= t <= x ) exp ( -t^3 ) dt
%
%    The data was reported by McLeod.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    16 September 2004
%
%  Author:
%
%    John Burkardt
%
%  Reference:
%
%    Allan McLeod,
%    Algorithm 757, MISCFUN: A software package to compute uncommon
%      special functions,
%    ACM Transactions on Mathematical Software,
%    Volume 22, Number 3, September 1996, pages 288-301.
%
%  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 = 20;

  fx_vec = [ ...
      0.19531249963620212007E-02, ...
      0.78124990686775522671E-02, ...
      0.31249761583499728667E-01, ...
      0.12493899888803079984E+00, ...
      0.48491714311363971332E+00, ...
      0.80751118213967145286E+00, ...
      0.86889265412623270696E+00, ...
      0.88861722235357162648E+00, ...
      0.89286018500218176869E+00, ...
      0.89295351429387631138E+00, ...
      0.89297479112737843939E+00, ...
      0.89297880579798112220E+00, ...
      0.89297950317496621294E+00, ...
      0.89297951152951902903E+00, ...
      0.89297951156918122102E+00, ...
      0.89297951156924734716E+00, ...
      0.89297951156924917298E+00, ...
      0.89297951156924921121E+00, ...
      0.89297951156924921122E+00, ...
      0.89297951156924921122E+00 ];

  x_vec = [ ...
      0.0019531250E+00, ...
      0.0078125000E+00, ...
      0.0312500000E+00, ...
      0.1250000000E+00, ...
      0.5000000000E+00, ...
      1.0000000000E+00, ...
      1.2500000000E+00, ...
      1.5000000000E+00, ...
      1.8750000000E+00, ...
      2.0000000000E+00, ...
      2.1250000000E+00, ...
      2.2500000000E+00, ...
      2.5000000000E+00, ...
      2.7500000000E+00, ...
      3.0000000000E+00, ...
      3.1250000000E+00, ...
      3.2500000000E+00, ...
      3.5000000000E+00, ...
      3.7500000000E+00, ...
      4.0000000000E+00 ];       

  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
