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

%*****************************************************************************80
%
%% EXP_VALUES returns some values of the exponential function.
%
%  Discussion:
%
%    In Mathematica, the function can be evaluated by:
%
%      Exp[x]
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    18 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 = 19;

  fx_vec = [ ...
    0.000045399929762484851536E+00, ...
    0.0067379469990854670966E+00, ...
    0.36787944117144232160E+00, ...
    1.0000000000000000000E+00, ...
    1.1051709180756476248E+00, ...
    1.2214027581601698339E+00, ...
    1.3498588075760031040E+00, ...
    1.4918246976412703178E+00, ...
    1.6487212707001281468E+00, ...
    1.8221188003905089749E+00, ...
    2.0137527074704765216E+00, ...
    2.2255409284924676046E+00, ...
    2.4596031111569496638E+00, ...
    2.7182818284590452354E+00, ...
    7.3890560989306502272E+00, ...
    23.140692632779269006E+00, ...
     148.41315910257660342E+00, ...
    22026.465794806716517E+00, ...
    4.8516519540979027797E+08 ];

  x_vec = [ ...
     -10.0E+00, ...
      -5.0E+00, ...
      -1.0E+00, ...
       0.0E+00, ...
       0.1E+00, ...
       0.2E+00, ...
       0.3E+00, ...
       0.4E+00, ...
       0.5E+00, ...
       0.6E+00, ...
       0.7E+00, ...
       0.8E+00, ...
       0.9E+00, ...
       1.0E+00, ...
       2.0E+00, ...
       3.1415926535897932385E+00, ...
       5.0E+00, ...
      10.0E+00, ...
      20.0E+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
