function f = p39_f ( x )

%*****************************************************************************80
%
%% p39_f() evaluates the objective function for test 39.
%
%  Licensing:
%
%    This code is distributed under the MIT license.
%
%  Modified:
%
%    23 February 2026
%
%  Author:
%
%    John Burkardt
%
%  Input:
%
%    real x: the argument.
%
%  Output:
%
%    real f: the function value.
%
  f = 25.0 * ( x - 1.0 ) ...
    + max ( ...
    - 2.0 * ( x - 1.0 ), ...
      8.0 * ( x - 1.0 ) );

  return
end

