function [ n_data, tc, p, eta ] = viscosity_values ( n_data )

%*****************************************************************************80
%
%% VISCOSITY_VALUES returns some values of the viscosity function.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    19 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, page 263.
%
%  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 TC, the temperature, in degrees Celsius.
%
%    Output, real P, the pressure, in bar.
%
%    Output, real ETA, the viscosity, in MegaPascal seconds.
%
  n_max = 34;

  eta_vec = [ ...
     1792.0E+00, ...
     1791.0E+00, ...
     1790.0E+00, ...
     1786.0E+00, ...
     1780.0E+00, ...
     1775.0E+00, ...
     1769.0E+00, ...
     1764.0E+00, ...
     1759.0E+00, ...
     1754.0E+00, ...
     1749.0E+00, ...
     1744.0E+00, ...
     1739.0E+00, ...
     1735.0E+00, ...
     1731.0E+00, ...
     1722.0E+00, ...
     1714.0E+00, ...
     1707.0E+00, ...
     1700.0E+00, ...
     1694.0E+00, ...
     1687.0E+00, ...
     1682.0E+00, ...
     1676.0E+00, ...
     1667.0E+00, ...
     1659.0E+00, ...
     1653.0E+00, ...
      890.8E+00, ...
      547.1E+00, ...
      378.4E+00, ...
      12.28E+00, ...
      16.18E+00, ...
      24.45E+00, ...
      32.61E+00, ...
      40.38E+00 ];

  p_vec = [ ...
        1.0E+00, ...
        5.0E+00, ...
       10.0E+00, ...
       25.0E+00, ...
       50.0E+00, ...
       75.0E+00, ...
      100.0E+00, ...
      125.0E+00, ...
      150.0E+00, ...
      175.0E+00, ...
      200.0E+00, ...
      225.0E+00, ...
      250.0E+00, ...
      275.0E+00, ...
      300.0E+00, ...
      350.0E+00, ...
      400.0E+00, ...
      450.0E+00, ...
      500.0E+00, ...
      550.0E+00, ...
      600.0E+00, ...
      650.0E+00, ...
      700.0E+00, ...
      800.0E+00, ...
      900.0E+00, ...
     1000.0E+00, ...
        1.0E+00, ...
        1.0E+00, ...
        1.0E+00, ...
        1.0E+00, ...
        1.0E+00, ...
        1.0E+00, ...
        1.0E+00, ...
        1.0E+00 ];

  tc_vec = [ ...
       0.0E+00, ...
       0.0E+00, ...
       0.0E+00, ...
       0.0E+00, ...
       0.0E+00, ...
       0.0E+00, ...
       0.0E+00, ...
       0.0E+00, ...
       0.0E+00, ...
       0.0E+00, ...
       0.0E+00, ...
       0.0E+00, ...
       0.0E+00, ...
       0.0E+00, ...
       0.0E+00, ...
       0.0E+00, ...
       0.0E+00, ...
       0.0E+00, ...
       0.0E+00, ...
       0.0E+00, ...
       0.0E+00, ...
       0.0E+00, ...
       0.0E+00, ...
       0.0E+00, ...
       0.0E+00, ...
       0.0E+00, ...
      25.0E+00, ...
      50.0E+00, ...
      75.0E+00, ...
     100.0E+00, ...
     200.0E+00, ...
     400.0E+00, ...
     600.0E+00, ...
     800.0E+00 ];

  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;
    eta = 0.0;
  else
    tc = tc_vec(n_data);
    p = p_vec(n_data);
    eta = eta_vec(n_data);
  end

  return
end
