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[sungskim@xxxxxxx]

Hello, Dolfin Developers !
I am a graduate student in math department at UW-Milwaukee.
Currently, I am exploring Dolfin User’s Manual. I tried to solve the 3D
Poisson’s equation by following the user’s manual Chaper 7, with the
Right_Hand_Side
f(x,y,z) = xzsin(y) in the unit cube
I run the following Poisson.form and main.cpp. However, I think it doesn’t work.
 Would you please send me any comment or correction for the code in the manual?

----- main.cpp --------
#include <dolphin.h>
#include “Poisson.h”

using namespace dolphin ;

//Right Hand Side
class MyFunction : public Function
{
   real  operator( )  (const  Point&  p)  const
  {   return  p.x*p.z*sin(p.y) ;   }
} ;

//Boundary Condition
class  MyBC : public  BoundaryCondition
{
  const  BoundaryValue  operator( ) (const  Point& p)
  {
    BoundaryValue  value ;
    if (std::abs(p.x – 0.0) < DOLFIN_EPS)  value = 0.0 ;
    if (std::abs(p.x – 1.0) < DOLFIN_EPS)  value = 0.0 ;
    if (std::abs(p.y – 0.0) < DOLFIN_EPS)  value = 0.0 ;
    if (std::abs(p.y – 1.0) < DOLFIN_EPS)  value = 0.0 ;
    if (std::abs(p.z – 0.0) < DOLFIN_EPS)  value = 0.0 ;
    if (std::abs(p.z – 1.0) < DOLFIN_EPS)  value = 0.0 ;
    return value ;
  }
} ;

int main( )
{
  //Set the problem
  MyFunction  f ;
  MyBC  bc ;
  Poisson :: BilinearForm  a ;
  Poisson :: LinearForm  L(f) ;


  Mesh  mesh ;
  Mat  A ;
  Vec   b ;
  FEM::assemble(a, L, A, b, mesh, bc) ;

  //Solve the linear system
  GMRES solver ;
  Solver.solve(A, x, b) ;

  //Save function to file
  Function  u(x, mesh, a.trial( ) ) ;
  File file(“poisson.pvd”) ;
  File << u ;
  return ( ) ;
}

=========================================

------- Poisson.form -----------------------------

#The bilinear form a(u,v) and linear form L(v) for
#Poisson’s equation.
#
#Compile this form with  FFC : ffc poisson.form.

element = FiniteElement(“Lagrange”,”tetrahedron”,1)

v = BasisFunction(element)
u = BasisFunction(element)
f = Function(element)

a = v.dx(i)*u.dx(i)*dx
L = v*f*dx
==============================================

I just followed Chapter 7 in the manual. It didn’t work.
Would you help me, please. Please send me any comment or correction.
(Poisson.form was successfully compiled to Poisson.h by ffc)
I think, main.cpp should be corrected. Help me.