function [ n_data, x, fx ] = bessel_j0_int_values ( n_data )

%*****************************************************************************80
%
%% BESSEL_J0_INT_VALUES returns some values of the Bessel J0 integral.
%
%  Discussion:
%
%    The function is defined by:
%
%      J0_INT(x) = Integral ( 0 <= t <= x ) J0(t) dt
%
%    The data was reported by McLeod.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    29 August 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 = [ ...
      0.97656242238978822427E-03, ...
      0.39062450329491108875E-02, ...
     -0.62479657927917933620E-01, ...
      0.12483733492120479139E+00, ...
     -0.48968050664604505505E+00, ...
      0.91973041008976023931E+00, ...
     -0.14257702931970265690E+01, ...
      0.10247341594606064818E+01, ...
     -0.12107468348304501655E+01, ...
      0.11008652032736190799E+01, ...
     -0.10060334829904124192E+01, ...
      0.81330572662485953519E+00, ...
     -0.10583788214211277585E+01, ...
      0.87101492116545875169E+00, ...
     -0.88424908882547488420E+00, ...
      0.11257761503599914603E+01, ...
     -0.90141212258183461184E+00, ...
      0.91441344369647797803E+00, ...
     -0.94482281938334394886E+00, ...
      0.92266255696016607257E+00 ];

  x_vec = [ ...
       0.0009765625E+00, ...
       0.0039062500E+00, ...
      -0.0625000000E+00, ...
       0.1250000000E+00, ...
      -0.5000000000E+00, ...
       1.0000000000E+00, ...
      -2.0000000000E+00, ...
       4.0000000000E+00, ...
      -8.0000000000E+00, ...
      16.0000000000E+00, ...
     -16.5000000000E+00, ...
      18.0000000000E+00, ...
     -20.0000000000E+00, ...
      25.0000000000E+00, ...
     -30.0000000000E+00, ...
      40.0000000000E+00, ...
     -50.0000000000E+00, ...
      75.0000000000E+00, ...
     -80.0000000000E+00, ...
     100.0000000000E+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

