//-----------------------------------------------------------------------------
void EpetraVector::gather(std::vector<double>& x,
const std::vector<dolfin::la_index>& indices) const
{
const std::size_t _size = indices.size();
x.resize(_size);
dolfin_assert(x.size() == _size);
// Gather values into a vector
EpetraVector y;
this->gather(y, indices);
dolfin_assert(y.size() == _size);
const Epetra_FEVector& _y = *(y.vec());
// Copy values into x
for (std::size_t i = 0; i < _size; ++i)
x[i] = (_y)[0][i];
}
//-----------------------------------------------------------------------------
std::size_t EpetraKrylovSolver::solve(EpetraVector& x, const EpetraVector& b)
{
dolfin_assert(solver);
dolfin_assert(_A);
dolfin_assert(_P);
// Check dimensions
const std::size_t M = _A->size(0);
const std::size_t N = _A->size(1);
if (N != b.size())
{
dolfin_error("EpetraKrylovSolver.cpp",
"solve linear system using Epetra Krylov solver",
"Non-matching dimensions for linear system");
}
// Write a message
const bool report = parameters["report"];
if (report && dolfin::MPI::process_number() == 0)
info("Solving linear system of size %d x %d (Epetra Krylov solver).", M, N);
// Reinitialize solution vector if necessary
if (x.size() != M)
{
_A->resize(x, 1);
x.zero();
}
else if (!parameters["nonzero_initial_guess"])
x.zero();
// Create linear problem
Epetra_LinearProblem linear_problem(_A->mat().get(), x.vec().get(),
b.vec().get());
// Set-up linear solver
solver->SetProblem(linear_problem);
// Set output level
if (parameters["monitor_convergence"])
{
const std::size_t interval = parameters["monitor_interval"];
solver->SetAztecOption(AZ_output, interval);
}
else
solver->SetAztecOption(AZ_output, AZ_none);
dolfin_assert(_P);
_preconditioner->set(*this, *_P);
// Set covergence check method
solver->SetAztecOption(AZ_conv, AZ_rhs);
// Start solve
solver->Iterate(static_cast<int>(parameters["maximum_iterations"]),
parameters["relative_tolerance"]);
// Check solve status
const double* status = solver->GetAztecStatus();
if ((int) status[AZ_why] != AZ_normal)
{
std::string errorDescription;
if( status[AZ_why] == AZ_maxits )
errorDescription = "maximum iters reached";
else if( status[AZ_why] == AZ_loss )
errorDescription = "loss of accuracy";
else if( status[AZ_why] == AZ_ill_cond )
errorDescription = "ill-conditioned";
else if( status[AZ_why] == AZ_breakdown )
errorDescription = "breakdown";
else
errorDescription = "unknown error";
std::stringstream message;
message << "Epetra (AztecOO) Krylov solver (" << _method << ", " << _preconditioner->name() << ") "
<< "failed to converge after " << (int)status[AZ_its] << " iterations "
<< "(" << errorDescription << ", error code " << (int)status[AZ_why] << ")";
if (parameters["error_on_nonconvergence"])
{
dolfin_error("EpetraKrylovSolver.cpp",
"solve linear system using Epetra Krylov solver",
message.str());
}
else
warning(message.str());
}
else
{
info("Epetra (AztecOO) Krylov solver (%s, %s) converged in %d iterations.",
_method.c_str(), _preconditioner->name().c_str(), solver->NumIters());
}
// Update residuals
absolute_residual = solver->TrueResidual();
relative_residual = solver->ScaledResidual();
// Return number of iterations
return solver->NumIters();
}