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

%*****************************************************************************80
%
%% SQRT_VALUES returns some values of the square root function.
%
%  Discussion:
%
%    SQRT(X) = positive real number Y such that Y * Y = X.
%
%    In Mathematica, the function can be evaluated by:
%
%      Sqrt[x]
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    19 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 = 14;

  fx_vec = [ ...
     0.0000000000000000E+00, ...      
     0.9000000040950000E-04, ...
     0.3000000000000000E+00, ...
     0.3162277660168379E+00, ...
     0.6324555320336759E+00, ...
     0.1000000000000000E+01, ...
     0.1414213562373095E+01, ...
     0.1732050807568877E+01, ...
     0.1772453850905516E+01, ...
     0.4358898943540674E+01, ...
     0.5385164807134504E+01, ...
     0.8426149773176359E+01, ...
     0.9848857801796105E+01, ...
     0.1111111106055556E+05 ];

  x_vec = [ ...
     0.0000000000000000E+00, ...
     0.8100000073710001E-08, ...
     0.9000000000000000E-01, ...
     0.1000000000000000E+00, ...
     0.4000000000000000E+00, ...
     0.1000000000000000E+01, ... 
     0.2000000000000000E+01, ...
     0.3000000000000000E+01, ...
     0.3141592653589793E+01, ...
     0.1900000000000000E+02, ...
     0.2900000000000000E+02, ...
     0.7100000000000000E+02, ...
     0.9700000000000000E+02, ...
     0.1234567890000000E+09 ];

  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