function value = u_exact ( x, problem )

%% U_EXACT returns the value of the exact solution at a point X.
%
%  Modified:
%
%    01 November 2006
%
%  Parameters:
%
%    Input, real X, the evaluation point.
%
%    Input, integer PROBLEM, indicates which problem to be solved.
%    * 1, u = x, p=1, q=0, f=x, u(0)=0, u'(1)=1.
%    * 2, u = 2*(1-cos(0.5*pi*x))/pi, p=1, q=0,
%    f = -0.5*pi*cos(0.5*pi*x) + 2*sin(0.5*pi*x)*(1-cos(0.5*pi*x)/pi
%    u(0) = 0, u'(1)=1.
%
%    Output, real VALUE, the value of the exact solution at X.
%

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

    value = x;
%
%  Test problem 2
%
  elseif ( problem == 2 )

    value = 2.0 * ( 1.0 - cos ( 0.5 * pi * x ) ) / pi;

  end