// example19.edp
// Book: Example 2.1, p. 11.

// defining the boundary
border C(t=0,2*pi){x=cos(t); y=sin(t);}
// the triangulated domain Th is on the left side of its boundary
// because boundary parameterization is CCW

// plot(C(50),wait=true,ps="boundary19.eps");

mesh Th = buildmesh (C(50));

// plot(Th, wait=true, ps="mesh19.eps");

                // the finite element space defined over Th is called here Vh
fespace Vh(Th,P1);

Vh u,v;               // defines u and v as piecewise-P1 continuous functions

func f= x*y;                             // definition of a called f function

real cpu=clock();                                  // get the clock in second

solve Poisson(u,v, solver=UMFPACK) =                       // defines the PDE
  int2d(Th)( dx(u)*dx(v) + dy(u)*dy(v) )                     // bilinear part
  - int2d(Th)( f*v )                                       // right hand side
   + on(C, u=0) ;                             // Dirichlet boundary condition

plot(u, ps="solution19.eps");                                // plot solution

cout << " CPU time = " << clock()-cpu << endl;         // print time required