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

%*****************************************************************************80
%
%% bessel_jx_values() returns some values of the Jx Bessel function.
%
%  Discussion:
%
%    This set of data considers the less common case in which the
%    index of the Bessel function Jn is actually not an integer.
%    We may suggest this case by occasionally replacing the symbol
%    "Jn" by "Jx".
%
%    In Mathematica, the function can be evaluated by:
%
%      BesselJ[n,x]
%
%  Licensing:
%
%    This code is distributed under the MIT license.
%
%  Modified:
%
%    01 April 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.
%
%  Input:
%
%    integer N_DATA.  The user sets N_DATA to 0 before the
%    first call.
%
%  Output:
%
%    integer N_DATA.  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.
%
%    real NU, the order of the function.
%
%    real X, the argument of the function.
%
%    real FX, the value of the function.
%
  n_max = 28;

  fx_vec = [ ...
        0.3544507442114011E+00, ...
        0.6713967071418031E+00, ...
        0.5130161365618278E+00, ...
        0.3020049060623657E+00, ...
        0.06500818287737578E+00, ...
       -0.3421679847981618E+00, ...
       -0.1372637357550505E+00, ...
        0.1628807638550299E+00, ...
        0.2402978391234270E+00, ...
        0.4912937786871623E+00, ...
       -0.1696513061447408E+00, ...
        0.1979824927558931E+00, ...
       -0.1094768729883180E+00, ...
        0.04949681022847794E+00, ...
        0.2239245314689158E+00, ...
        0.2403772011113174E+00, ...
        0.1966584835818184E+00, ...
        0.02303721950962553E+00, ...
        0.3314145508558904E+00, ...
        0.5461734240402840E+00, ...
       -0.2616584152094124E+00, ...
        0.1296035513791289E+00, ...
       -0.1117432171933552E+00, ...
        0.03142623570527935E+00, ...
        0.1717922192746527E+00, ...
        0.3126634069544786E+00, ...
        0.1340289119304364E+00, ...
        0.06235967135106445E+00 ];

  nu_vec = [ ...
    0.50E+00, ...
    0.50E+00, ...
    0.50E+00, ...
    0.50E+00, ...
    0.50E+00, ...
    0.50E+00, ...
    0.50E+00, ...
    0.50E+00, ...
    1.50E+00, ...
    1.50E+00, ...
    1.50E+00, ...
    1.50E+00, ...
    1.50E+00, ...
    2.50E+00, ...
    2.50E+00, ...
    2.50E+00, ...
    2.50E+00, ...
    2.50E+00, ...
    1.25E+00, ...
    1.25E+00, ...
    1.25E+00, ...
    1.25E+00, ...
    1.25E+00, ...
    2.75E+00, ...
    2.75E+00, ...
    2.75E+00, ...
    2.75E+00, ...
    2.75E+00 ];

  x_vec = [ ...
      0.2E+00, ...
      1.0E+00, ...
      2.0E+00, ...
      2.5E+00, ...
      3.0E+00, ...
      5.0E+00, ...
     10.0E+00, ...
     20.0E+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, ...
      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 = 0.0;
    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
