Teko_DiagonalPreconditionerOp.cpp

// @HEADER
// *****************************************************************************
//      Teko: A package for block and physics based preconditioning
//
// Copyright 2010 NTESS and the Teko contributors.
// SPDX-License-Identifier: BSD-3-Clause
// *****************************************************************************
// @HEADER

#include "Teko_DiagonalPreconditionerOp.hpp"
#include "Thyra_EpetraThyraWrappers.hpp"
#include "EpetraExt_PointToBlockDiagPermute.h"
#include "Epetra_MultiVector.h"

using Teuchos::RCP;
using Teuchos::rcp_const_cast;
using Teuchos::rcp_dynamic_cast;
using Teuchos::rcpFromRef;

using Thyra::MultiVectorBase;

namespace Teko {

DiagonalPreconditionerOp::DiagonalPreconditionerOp(
    Teuchos::RCP<EpetraExt_PointToBlockDiagPermute> BDP, const VectorSpace range,
    const VectorSpace domain)
    : BDP_(BDP), range_(range), domain_(domain) {}

void DiagonalPreconditionerOp::implicitApply(const MultiVector& x, MultiVector& y,
                                             const double alpha, const double beta) const {
  // Get the Multivectors into Epetra land
  // NTS: Thyra inexplicably wants maps, even when they are completely unecessary.
  const Epetra_Map& rangemap_  = BDP_->OperatorRangeMap();
  const Epetra_Map& domainmap_ = BDP_->OperatorDomainMap();

  RCP<const Epetra_MultiVector> x_ = Thyra::get_Epetra_MultiVector(domainmap_, x);
  RCP<Epetra_MultiVector> y_       = Thyra::get_Epetra_MultiVector(rangemap_, y);
  TEUCHOS_ASSERT(x_ != Teuchos::null);
  TEUCHOS_ASSERT(y_ != Teuchos::null);

  // y = \alpha M x + \beta y $
  if (beta == 0.0) {
    BDP_->ApplyInverse(*x_, *y_);
    scale(alpha, y);
  } else {
    MultiVector y0 = deepcopy(y);
    BDP_->ApplyInverse(*x_, *y_);
    update(alpha, y, beta, y0);
  }
}

void DiagonalPreconditionerOp::describe(Teuchos::FancyOStream& out_arg,
                                        const Teuchos::EVerbosityLevel verbLevel) const {
  using Teuchos::OSTab;

  switch (verbLevel) {
    case Teuchos::VERB_DEFAULT:
    case Teuchos::VERB_LOW: out_arg << this->description() << std::endl; break;
    case Teuchos::VERB_MEDIUM:
    case Teuchos::VERB_HIGH:
    case Teuchos::VERB_EXTREME:
      if (BDP_ != Teuchos::null) BDP_->Print(out_arg);
      break;
    default: TEUCHOS_TEST_FOR_EXCEPT(true);  // Should never get here!
  }
}

}  // end namespace Teko