function errors_test28 ( )

%*****************************************************************************80
%
%% errors_test28() evaluates a polynomial.
%
%  Licensing:
%
%    This code is distributed under the MIT license.
%
%  Modified:
%
%    13 November 2019
%
%  Author:
%
%    John Burkardt
%
  fprintf ( 1, '\n' );
  fprintf ( 1, '+=============================================+\n' );
  fprintf ( 1, '|                                             |\n' );
  fprintf ( 1, '|  Exercise 28                                |\n' );
  fprintf ( 1, '|                                             |\n' );
  fprintf ( 1, '|  f(x,y)= 333.75 y^6                         |\n' );
  fprintf ( 1, '|    + x^2 (11x^2y^2-y^6-121y^4-2)            |\n' );
  fprintf ( 1, '|    + 5.5y^8 + x/2/y                         |\n' );
  fprintf ( 1, '|                                             |\n' );
  fprintf ( 1, '|  Evaluate f(x,y) at:                        |\n' );
  fprintf ( 1, '|                                             |\n' );
  fprintf ( 1, '|    x = 77617, y = 33096.                    |\n' );
  fprintf ( 1, '|                                             |\n' );
  fprintf ( 1, '|  The correct answer:                        |\n' );
  fprintf ( 1, '|                                             |\n' );
  fprintf ( 1, '|    f(77617,33096) = -0.827...               |\n' );
  fprintf ( 1, '|                                             |\n' );
  fprintf ( 1, '+=============================================+\n' );

  x = 77617.0;
  y = 33096.0;
  f = 333.75 * y^6 ...
    + x^2 * ( 11.0 * x^2 * y^2 - y^6 - 121.0 * y^4 - 2.0 ) ...
    + 5.5 * y^8 + x / 2.0 / y; 

  f_exact = - 0.827;

  fprintf ( 1, '\n' )
  fprintf ( 1, '  Computed result              = %g\n', f );
  fprintf ( 1, '  Correct result (to 3 digits) = %g\n', f_exact );

  return
end
