function value = ff ( x )

%% FF returns the right hand side of the differential equation.
%
%  Modified:
%
%    09 November 2006
%
%  Author:
%
%    MATLAB version by John Burkardt
%
%  Parameters:
%
%    Input, real X, the evaluation point.
%
%    Output, real VALUE, the value of F(X).
%
  value = 0.0;