//-----------------------------------------------------------------------------
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");
}
//-----------------------------------------------------------------------------
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;
}