function [ n_data, nu, x, fx ] = bessel_jn_values ( n_data )

%*****************************************************************************80
%
%% BESSEL_JN_VALUES returns some values of the Jn Bessel function.
%
%  Discussion:
%
%    In Mathematica, the function can be evaluated by:
%
%      BesselJ[n,x]
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    29 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, integer NU, the order of the function.
%
%    Output, real X, the argument of the function.
%
%    Output, real FX, the value of the function.
%
  n_max = 20;

  fx_vec = [ ...
      0.1149034849319005E+00, ...
      0.3528340286156377E+00, ...
      0.4656511627775222E-01, ...
      0.2546303136851206E+00, ...
     -0.5971280079425882E-01, ...
      0.2497577302112344E-03, ...
      0.7039629755871685E-02, ...
      0.2611405461201701E+00, ...
     -0.2340615281867936E+00, ...
     -0.8140024769656964E-01, ...
      0.2630615123687453E-09, ...
      0.2515386282716737E-06, ...
      0.1467802647310474E-02, ...
      0.2074861066333589E+00, ...
     -0.1138478491494694E+00, ...
      0.3873503008524658E-24, ...
      0.3918972805090754E-18, ...
      0.2770330052128942E-10, ...
      0.1151336924781340E-04, ...
     -0.1167043527595797E+00 ];

  nu_vec = [ ...
     2,  2,  2,  2, ...
     2,  5,  5,  5, ...
     5,  5, 10, 10, ...
    10, 10, 10, 20, ...
    20, 20, 20, 20 ];

  x_vec = [ ...
      1.0E+00, ... 
      2.0E+00, ...
      5.0E+00, ...
     10.0E+00, ...
     50.0E+00, ...
      1.0E+00, ...
      2.0E+00, ...
      5.0E+00, ...
     10.0E+00, ...
     50.0E+00, ...
      1.0E+00, ...
      2.0E+00, ...
      5.0E+00, ...
     10.0E+00, ...
     50.0E+00, ...
      1.0E+00, ...
      2.0E+00, ...
      5.0E+00, ...
     10.0E+00, ...
     50.0E+00 ];

  if ( n_data < 0 )
    n_data = 0;
  end

  n_data = n_data + 1;

  if ( n_max < n_data )
    n_data = 0;
    nu = 0;
    x = 0.0;
    fx = 0.0;
  else
    nu = nu_vec(n_data);
    x = x_vec(n_data);
    fx = fx_vec(n_data);
  end

  return
end
