function value = ff ( x, problem )

%% FF evaluates the right hand side function F(X) at any point X.
%
%  Modified:
%
%    03 November 2006
%
%  Author:
%
%    Max Gunzburger
%    Teresa Hodge
%
%    MATLAB translation by John Burkardt
%
%  Parameters:
%
%    Input, real X, the evaluation point.
%
%    Input, integer PROBLEM, indicates the problem being solved.
%    1, U=1-x**4, P=1, Q=1, F=1.0+12.0*x**2-x**4.
%    2, U=cos(0.5*pi*x), P=1, Q=0, F=0.25*pi*pi*cos(0.5*pi*x).
%
%    Output, real VALUE, the value of F(X).
%

%
%  Test problem 1
%
  if ( problem == 1 )

    value = 1.0 + 12.0 * x^2 - x^4;
%
%  Test problem 2
%
  elseif ( problem == 2 )

    value = 0.25 * pi * pi * cos ( 0.5 * pi * x );

  end