Beispiel #1
0
//-----------------------------------------------------------------------------
double dolfin::residual(const GenericLinearOperator& A,
                        const GenericVector& x,
                        const GenericVector& b)
{
  std::shared_ptr<GenericVector> y = x.factory().create_vector(x.mpi_comm());
  A.mult(x, *y);
  *y -= b;
  return y->norm("l2");
}
Beispiel #2
0
//-----------------------------------------------------------------------------
bool dolfin::in_nullspace(const GenericLinearOperator& A,
                          const VectorSpaceBasis& basis, std::string type)
{
  // Tolerance (maybe this should be a parameter?)
  const double tol = 1.0e-7;

  // Get dimension, and return if basis is empty
  const std::size_t dim = basis.dim();
  if (dim == 0)
    return true;

  // Get factory and create vector for LHS
  dolfin_assert(basis[0]);
  GenericLinearAlgebraFactory& factory = basis[0]->factory();
  std::shared_ptr<GenericVector> y = factory.create_vector(basis[0]->mpi_comm());

  const GenericMatrix* _A = NULL;
  if (type == "right")
  {
    // Do nothing
  }
  else if (type == "left")
  {
    const GenericMatrix* _A = dynamic_cast<const GenericMatrix*>(&A);
    if (!_A)
    {
      dolfin_error("test_nullspace.cpp",
                   "calling is_nullspace(...)",
                   "Left nullspace can be tested for GenericMatrix only (not GenericLinearOperator)");
    }
  }
  else
  {
    dolfin_error("test_nullspace.cpp",
                 "calling is_nullspace(...)",
                 "Left nullspace can be tested for GenericMatrix only (not GenericLinearOperator)");
  }

  // Test nullspace
  for (std::size_t i = 0; i < dim; ++i)
  {
    std::shared_ptr<const GenericVector> x = basis[i];
    dolfin_assert(x);
    if (!_A)
      A.mult(*x, *y);
    else
      _A->transpmult(*x, *y);

    if (y->norm("l2") > tol)
      return false;
  }

  return true;
}
  int usermult(Mat A, Vec x, Vec y)
  {
    // Wrap PETSc Vec as dolfin::PETScVector
    boost::shared_ptr<Vec> _x(&x, NoDeleter());
    boost::shared_ptr<Vec> _y(&y, NoDeleter());
    PETScVector __x(_x);
    PETScVector __y(_y);

    // Extract pointer to PETScLinearOperator
    void* ctx = 0;
    MatShellGetContext(A, &ctx);
    PETScLinearOperator* _A = ((PETScLinearOperator*) ctx);

    // Call user-defined mult function through wrapper
    dolfin_assert(_A);
    GenericLinearOperator* wrapper = _A->wrapper();
    dolfin_assert(wrapper);
    wrapper->mult(__x, __y);

    return 0;
  }