function [ n_data, x, fx ] = bessel_y0_spherical_values ( n_data )

%*****************************************************************************80
%
%% bessel_y0_spherical_values() returns some values of the Spherical Bessel function y0.
%
%  Discussion:
%
%    In Mathematica, the function can be evaluated by:
%
%      Sqrt[Pi/(2*x)] * BesselY[1/2,x]
%
%  Licensing:
%
%    This code is distributed under the MIT license.
%
%  Modified:
%
%    24 August 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.
%
%  Input:
%
%    integer N_DATA.  The user sets N_DATA to 0 before the first call.  
%    Thereafter, it should simply be the value returned by the previous 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 X, the argument of the function.
%
%    real FX, the value of the function.
%
  n_max = 21;

  fx_vec = [ ...
     -0.9950041652780258E+01, ...
     -0.4900332889206208E+01, ...
     -0.2302652485007213E+01, ...
     -0.1375559358182797E+01, ...
     -0.8708833866839568E+00, ...
     -0.5403023058681397E+00, ...
     -0.3019647953972280E+00, ...
     -0.1214051020716007E+00, ...
      0.1824970143830545E-01, ...
      0.1262233859406039E+00, ...
      0.2080734182735712E+00, ...
      0.2675005078433390E+00, ...
      0.3072473814755190E+00, ...
      0.3295725974495951E+00, ...
      0.3365079788102351E+00, ...
      0.3299974988668152E+00, ...
      0.3119671174358603E+00, ...
      0.2843524095821944E+00, ...
      0.2490995600928186E+00, ...
      0.2081493978722149E+00, ... 
      0.1634109052159030E+00 ];

  x_vec = [ ...
     0.1E+00, ...
     0.2E+00, ...
     0.4E+00, ...
     0.6E+00, ...
     0.8E+00, ...
     1.0E+00, ...
     1.2E+00, ...
     1.4E+00, ...
     1.6E+00, ...
     1.8E+00, ...
     2.0E+00, ...
     2.2E+00, ...
     2.4E+00, ...
     2.6E+00, ...
     2.8E+00, ...
     3.0E+00, ...
     3.2E+00, ...
     3.4E+00, ...
     3.6E+00, ...
     3.8E+00, ...
     4.0E+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
