function f = p13_f ( x )

%*****************************************************************************80
%
%% p13_f() evaluates the objective function for problem 13.
%
%  Licensing:
%
%    This code is distributed under the MIT license.
%
%  Modified:
%
%    04 August 2019
%
%  Author:
%
%    John Burkardt
%
%  Input:
%
%    real x, the argument of the objective function.
%
%  Output:
%
%    real f, the value of the objective function.
%
  f = 2.0 * x.^4 - 7.0 * x.^2 + 3.0 * x + 5.0;

  return
end
