MueLu_EpetraOperator.cpp

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//        MueLu: A package for multigrid based preconditioning
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#include <Xpetra_Matrix.hpp>
#include <Xpetra_CrsMatrixWrap.hpp>
#include <Xpetra_BlockedCrsMatrix.hpp>
#include <Xpetra_EpetraMultiVector.hpp>

#include "MueLu_EpetraOperator.hpp"
#include "MueLu_Level.hpp"
#include "MueLu_Utilities.hpp"

namespace MueLu {

int EpetraOperator::ApplyInverse(const Epetra_MultiVector& X, Epetra_MultiVector& Y) const {
  try {
    // There is no rcpFromRef(const T&), so we need to do const_cast
    const Xpetra::EpetraMultiVector eX(rcpFromRef(const_cast<Epetra_MultiVector&>(X)));
    Xpetra::EpetraMultiVector       eY(rcpFromRef(Y));

    // Generally, we assume two different vectors, but AztecOO uses a single vector
    if (X.Values() == Y.Values()) {
      // X and Y point to the same memory, use an additional vector
      RCP<Xpetra::EpetraMultiVector> tmpY = Teuchos::rcp(new Xpetra::EpetraMultiVector(eY.getMap(), eY.getNumVectors()));

      // InitialGuessIsZero in MueLu::Hierarchy.Iterate() does not zero out components, it
      // only assumes that user provided an already zeroed out vector
      bool initialGuessZero = true;
      tmpY->putScalar(0.0);

      // apply one V-cycle as preconditioner
      Hierarchy_->Iterate(eX, *tmpY, 1, initialGuessZero);

      // deep copy solution from MueLu
      eY.update(1.0, *tmpY, 0.0);

    } else {
      // X and Y point to different memory, pass the vectors through

      // InitialGuessIsZero in MueLu::Hierarchy.Iterate() does not zero out components, it
      // only assumes that user provided an already zeroed out vector
      bool initialGuessZero = true;
      eY.putScalar(0.0);

      Hierarchy_->Iterate(eX, eY, 1, initialGuessZero);
    }

  } catch (std::exception& e) {
    //TODO: error msg directly on std::cerr?
    std::cerr << "Caught an exception in MueLu::EpetraOperator::ApplyInverse():" << std::endl
        << e.what() << std::endl;
    return -1;
  }

  return 0;
}

const Epetra_Comm& EpetraOperator::Comm() const {
  RCP<Matrix> A = Hierarchy_->GetLevel(0)->Get<RCP<Matrix> >("A");

  //TODO: This code is not pretty
  RCP<Xpetra::BlockedCrsMatrix<double, int, int> > epbA = Teuchos::rcp_dynamic_cast<Xpetra::BlockedCrsMatrix<double, int, int> >(A);
  if (epbA != Teuchos::null) {
    RCP<const Xpetra::EpetraCrsMatrix> tmp_ECrsMtx = rcp_dynamic_cast<Xpetra::EpetraCrsMatrix >(epbA->getMatrix(0,0));
    if (tmp_ECrsMtx == Teuchos::null)
      throw Exceptions::BadCast("Cast from Xpetra::CrsMatrix to Xpetra::EpetraCrsMatrix failed");

    RCP<Epetra_CrsMatrix> epA = tmp_ECrsMtx->getEpetra_CrsMatrixNonConst();
    return epA->Comm();
  }

  RCP<Epetra_CrsMatrix> epA = Utils::Op2NonConstEpetraCrs(A);
  return epA->Comm();
}

const Epetra_Map& EpetraOperator::OperatorDomainMap() const {
  RCP<Matrix> A = Hierarchy_->GetLevel(0)->Get<RCP<Matrix> >("A");

  RCP<Xpetra::BlockedCrsMatrix<double, int, int> > epbA = Teuchos::rcp_dynamic_cast<Xpetra::BlockedCrsMatrix<double, int, int> >(A);
  if (epbA != Teuchos::null)
    return Xpetra::toEpetra(epbA->getDomainMap());

  RCP<Epetra_CrsMatrix> epA = Utils::Op2NonConstEpetraCrs(A);
  return epA->DomainMap();
}

const Epetra_Map & EpetraOperator::OperatorRangeMap() const {
  RCP<Matrix> A = Hierarchy_->GetLevel(0)->Get<RCP<Matrix> >("A");

  RCP<Xpetra::BlockedCrsMatrix<double, int, int> > epbA = Teuchos::rcp_dynamic_cast<Xpetra::BlockedCrsMatrix<double, int, int> >(A);
  if (epbA != Teuchos::null)
    return Xpetra::toEpetra(epbA->getRangeMap());

  RCP<Epetra_CrsMatrix> epA = Utils::Op2NonConstEpetraCrs(A);
  return epA->RangeMap();
}

} // namespace