function [ n_data, x, fx ] = bessel_i1_values ( n_data )

%*****************************************************************************80
%
%% BESSEL_I1_VALUES returns some values of the I1 Bessel function.
%
%  Discussion:
%
%    The modified Bessel functions In(Z) and Kn(Z) are solutions of
%    the differential equation
%
%      Z^2 W'' + Z * W' - ( Z^2 + N^2 ) * W = 0.
%
%    In Mathematica, the function can be evaluated by:
%
%      BesselI[1,x]
%
%  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.
%
%    Stephen Wolfram,
%    The Mathematica Book,
%    Fourth Edition,
%    Wolfram Media / Cambridge University Press, 1999.
%
%  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 = [ ...
     0.0000000000000000E+00, ...
     0.1005008340281251E+00, ...
     0.2040267557335706E+00, ...
     0.3137040256049221E+00, ...
     0.4328648026206398E+00, ...
     0.5651591039924850E+00, ...
     0.7146779415526431E+00, ...
     0.8860919814143274E+00, ...
     0.1084810635129880E+01, ... 
     0.1317167230391899E+01, ...
     0.1590636854637329E+01, ...
     0.2516716245288698E+01, ...
     0.3953370217402609E+01, ...
     0.6205834922258365E+01, ...
     0.9759465153704450E+01, ...
     0.1538922275373592E+02, ...
     0.2433564214245053E+02, ...
     0.6134193677764024E+02, ...
     0.3998731367825601E+03, ...
     0.2670988303701255E+04 ];

  x_vec = [ ...
     0.00E+00, ...
     0.20E+00, ...
     0.40E+00, ...
     0.60E+00, ...
     0.80E+00, ...
     0.10E+01, ...
     0.12E+01, ...
     0.14E+01, ...
     0.16E+01, ...
     0.18E+01, ...
     0.20E+01, ...
     0.25E+01, ...
     0.30E+01, ...
     0.35E+01, ...
     0.40E+01, ...
     0.45E+01, ...
     0.50E+01, ...
     0.60E+01, ...
     0.80E+01, ...
     0.10E+02 ];

  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
