dolfin team mailing list archive

[oelgaard <k.b.oelgaard@xxxxxxxxxx>]

Public bug reported:

The following two files will reproduce the bug.

M.ufl:

exact = FiniteElement("Lagrange", triangle, 6)
approx = FiniteElement("Lagrange", triangle, 1)

u = Function(exact)
uh = Function(approx)

M = (uh - u)*(uh - u)*dx


main.cpp:

#include <dolfin.h>
#include "M.h"

using namespace dolfin;

class Expr : public Expression
{
public:

  Expr() : Expression(2) {}

  void eval(double* values, const double* x) const
  {
    values[0] = 10*x[0]*x[1];
  }

};

class Expr2 : public Expression
{
public:

  Expr2() : Expression(2) {}

  void eval(double* values, const double* x) const
  {
    values[0] = sin(5*x[0]);
  }
};

class Func2 : public Function
{
public:

  Func2(FunctionSpace& v) : Function(v) {}

  void eval(double* values, const double* x) const
  {
    values[0] = sin(5*x[0]);
  }
};

int main()
{
  // Create mesh and function space
  UnitSquare mesh(8, 8);
  M::CoefficientSpace_u Vu(mesh);
  M::CoefficientSpace_uh Vuh(mesh);

  Expr exact;
//  Expr2 approx;      // 12.5251
//  Func2 approx(Vuh); // 11.1111
  Func2 approx(Vu);    // 11.1111

  M::Functional m(mesh);
  m.u = exact;
  m.uh = approx;

  double error = assemble(m);

  std::cout << "error: " << error << std::endl;

  return 0;
}

** Affects: dolfin
     Importance: Undecided
         Status: New

-- 
function and expression does not give the same result
https://bugs.launchpad.net/bugs/457262
You received this bug notification because you are subscribed to DOLFIN.

Status in DOLFIN: New

Bug description:
The following two files will reproduce the bug.

M.ufl:

exact = FiniteElement("Lagrange", triangle, 6)
approx = FiniteElement("Lagrange", triangle, 1)

u = Function(exact)
uh = Function(approx)

M = (uh - u)*(uh - u)*dx


main.cpp:

#include <dolfin.h>
#include "M.h"

using namespace dolfin;

class Expr : public Expression
{
public:

  Expr() : Expression(2) {}

  void eval(double* values, const double* x) const
  {
    values[0] = 10*x[0]*x[1];
  }

};

class Expr2 : public Expression
{
public:

  Expr2() : Expression(2) {}

  void eval(double* values, const double* x) const
  {
    values[0] = sin(5*x[0]);
  }
};

class Func2 : public Function
{
public:

  Func2(FunctionSpace& v) : Function(v) {}

  void eval(double* values, const double* x) const
  {
    values[0] = sin(5*x[0]);
  }
};

int main()
{
  // Create mesh and function space
  UnitSquare mesh(8, 8);
  M::CoefficientSpace_u Vu(mesh);
  M::CoefficientSpace_uh Vuh(mesh);

  Expr exact;
//  Expr2 approx;      // 12.5251
//  Func2 approx(Vuh); // 11.1111
  Func2 approx(Vu);    // 11.1111

  M::Functional m(mesh);
  m.u = exact;
  m.uh = approx;

  double error = assemble(m);

  std::cout << "error: " << error << std::endl;

  return 0;
}