function [ n_data, tc, p ] = psat_values ( n_data )

%*****************************************************************************80
%
%% psat_values() returns some values of the saturation pressure.
%
%  Licensing:
%
%    This code is distributed under the MIT license.
%
%  Modified:
%
%    29 September 2004
%
%  Author:
%
%    John Burkardt
%
%  Reference:
%
%    Lester Haar, John Gallagher and George Kell,
%    NBS/NRC Steam Tables:
%    Thermodynamic and Transport Properties and Computer Programs
%      for Vapor and Liquid States of Water in SI Units,
%    Hemisphere Publishing Corporation, Washington, 1984,
%    TJ270.H3, pages 9-15.
%
%  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 TC, the temperature, in degrees Celsius.
%
%    real P, the saturation pressure, in bar.
%
  n_max = 12;

  p_vec = [ ...
     0.0061173E+00, ...
     0.0065716E+00, ...
     0.0087260E+00, ...
     0.12344E+00, ...
     1.0132E+00,  ...
     2.3201E+00,  ...
     4.7572E+00,  ...
     15.537E+00,  ...
     39.737E+00,  ...
     85.838E+00,  ...
     165.21E+00,  ...
     220.55E+00 ];

  tc_vec = [ ...
     0.100000E-01, ...
     0.100000E+01, ...
     0.500000E+01, ...
     0.500000E+02, ...
     0.100000E+03, ...
     0.125000E+03, ...
     0.150000E+03, ...
     0.200000E+03, ...
     0.250000E+03, ...
     0.300000E+03, ...
     0.350000E+03, ...
     0.373976E+03  ];

  if ( n_data < 0 )
    n_data = 0;
  end

  n_data = n_data + 1;

  if ( n_max < n_data )
    n_data = 0;
    tc = 0.0;
    p = 0.0;
  else
    tc = tc_vec(n_data);
    p = p_vec(n_data);
  end

  return
end
