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

%*****************************************************************************80
%
%% AIRY_GI_VALUES returns some values of the Airy Gi function.
%
%  Discussion:
%
%    The function is defined by:
%
%      AIRY_GI(x) = Integral ( 0 <= t < infinity ) sin ( x*t+t^3/3) dt / pi
%
%    The data was reported by McLeod.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    15 September 2004
%
%  Author:
%
%    John Burkardt
%
%  Reference:
%
%    Milton Abramowitz and Irene Stegun,
%    Handbook of Mathematical Functions,
%    US Department of Commerce, 1964.
%
%    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 = [ ...
      0.20468308070040542435E+00, ...
      0.18374662832557904078E+00, ...
     -0.11667221729601528265E+00, ...
      0.31466934902729557596E+00, ...
     -0.37089040722426257729E+00, ...
     -0.25293059772424019694E+00, ...
      0.28967410658692701936E+00, ...
     -0.34644836492634090590E+00, ...
      0.28076035913873049496E+00, ...
      0.21814994508094865815E+00, ...
      0.20526679000810503329E+00, ...
      0.22123695363784773258E+00, ...
      0.23521843981043793760E+00, ...
      0.82834303363768729338E-01, ...
      0.45757385490989281893E-01, ...
      0.44150012014605159922E-01, ...
      0.39951133719508907541E-01, ...
      0.35467706833949671483E-01, ...
      0.31896005100679587981E-01, ...
      0.26556892713512410405E-01 ];

  x_vec = [ ...
      -0.0019531250E+00, ...
      -0.1250000000E+00, ...
      -1.0000000000E+00, ...
      -4.0000000000E+00, ...
      -8.0000000000E+00, ...
      -8.2500000000E+00, ...
      -9.0000000000E+00, ...
     -10.0000000000E+00, ...
     -11.0000000000E+00, ...
     -13.0000000000E+00, ...
       0.0019531250E+00, ...
       0.1250000000E+00, ...
       1.0000000000E+00, ...
       4.0000000000E+00, ...
       7.0000000000E+00, ...
       7.2500000000E+00, ...
       8.0000000000E+00, ...
       9.0000000000E+00, ...
      10.0000000000E+00, ...
      12.0000000000E+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
