MueLu_IfpackSmoother.cpp

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// @HEADER
// *****************************************************************************
//        MueLu: A package for multigrid based preconditioning
//
// Copyright 2012 NTESS and the MueLu contributors.
// SPDX-License-Identifier: BSD-3-Clause
// *****************************************************************************
// @HEADER

#include "MueLu_ConfigDefs.hpp"

#if defined(HAVE_MUELU_EPETRA) && defined(HAVE_MUELU_IFPACK)
#include <Ifpack.h>
#include <Ifpack_Chebyshev.h>
#include "Xpetra_MultiVectorFactory.hpp"

#include "MueLu_IfpackSmoother.hpp"

#include "MueLu_Level.hpp"
#include "MueLu_Utilities.hpp"
#include "MueLu_Monitor.hpp"
#include "MueLu_Aggregates.hpp"

namespace MueLu {

template <class Node>
IfpackSmoother<Node>::IfpackSmoother(std::string const& type, Teuchos::ParameterList const& paramList, LO const& overlap)
  : type_(type)
  , overlap_(overlap) {
  this->declareConstructionOutcome(false, "");
  SetParameterList(paramList);
}

template <class Node>
void IfpackSmoother<Node>::SetParameterList(const Teuchos::ParameterList& paramList) {
  Factory::SetParameterList(paramList);

  if (SmootherPrototype::IsSetup()) {
    // It might be invalid to change parameters after the setup, but it depends entirely on Ifpack implementation.
    // TODO: I don't know if Ifpack returns an error code or exception or ignore parameters modification in this case...
    prec_->SetParameters(const_cast<ParameterList&>(this->GetParameterList()));
  }
}

template <class Node>
void IfpackSmoother<Node>::SetPrecParameters(const Teuchos::ParameterList& list) const {
  ParameterList& paramList = const_cast<ParameterList&>(this->GetParameterList());
  paramList.setParameters(list);

  RCP<ParameterList> precList = this->RemoveFactoriesFromList(this->GetParameterList());

  prec_->SetParameters(*precList);

  // We would like to have the following line here:
  //      paramList.setParameters(*precList);
  // For instance, if Ifpack sets somem parameters internally, we would like to have
  // them listed when we call this->GetParameterList()
  // But because of the way Ifpack handles the list, we cannot do that.
  // The bad scenario goes like this:
  //   * SmootherFactory calls Setup
  //   * Setup calls SetPrecParameters
  //   * We call prec_->SetParameters(*precList)
  //     This actually updates the internal parameter list  with default prec_ parameters
  //     This means that we get a parameter ("chebyshev: max eigenvalue", -1) in the list
  //   * Setup calls prec_->Compute()
  //     Here we may compute the max eigenvalue, but we get no indication of this. If we
  //     do compute it, our parameter list becomes outdated
  //   * SmootherFactory calls Apply
  //   * Apply constructs a list with a list with an entry "chebyshev: zero starting solution"
  //   * We call prec_->SetParameters(*precList)
  // The last call is the problem. At this point, we have a list with an outdated entry
  // "chebyshev: max eigenvalue", but prec_ uses this entry and replaces the computed max
  // eigenvalue with the one from the list, resulting in -1.0 eigenvalue.
  //
  // Ifpack2 does not have this problem, as it does not populate the list with new entries
}

template <class Node>
void IfpackSmoother<Node>::DeclareInput(Level& currentLevel) const {
  this->Input(currentLevel, "A");

  if (type_ == "LINESMOOTHING_BANDED_RELAXATION" ||
      type_ == "LINESMOOTHING_BANDED RELAXATION" ||
      type_ == "LINESMOOTHING_BANDEDRELAXATION" ||
      type_ == "LINESMOOTHING_BLOCK_RELAXATION" ||
      type_ == "LINESMOOTHING_BLOCK RELAXATION" ||
      type_ == "LINESMOOTHING_BLOCKRELAXATION") {
    this->Input(currentLevel, "CoarseNumZLayers");           // necessary for fallback criterion
    this->Input(currentLevel, "LineDetection_VertLineIds");  // necessary to feed block smoother
  }                                                          // if (type_ == "LINESMOOTHING_BANDEDRELAXATION")
  else if (type_ == "AGGREGATE") {
    // Aggregate smoothing needs aggregates
    this->Input(currentLevel, "Aggregates");
  }
}

template <class Node>
void IfpackSmoother<Node>::Setup(Level& currentLevel) {
  FactoryMonitor m(*this, "Setup Smoother", currentLevel);
  if (SmootherPrototype::IsSetup() == true)
    this->GetOStream(Warnings0) << "MueLu::IfpackSmoother::Setup(): Setup() has already been called" << std::endl;

  A_ = Factory::Get<RCP<Matrix> >(currentLevel, "A");

  double lambdaMax = -1.0;
  if (type_ == "Chebyshev") {
    std::string maxEigString   = "chebyshev: max eigenvalue";
    std::string eigRatioString = "chebyshev: ratio eigenvalue";

    try {
      lambdaMax = Teuchos::getValue<Scalar>(this->GetParameter(maxEigString));
      this->GetOStream(Statistics1) << maxEigString << " (cached with smoother parameter list) = " << lambdaMax << std::endl;

    } catch (Teuchos::Exceptions::InvalidParameterName&) {
      lambdaMax = A_->GetMaxEigenvalueEstimate();

      if (lambdaMax != -1.0) {
        this->GetOStream(Statistics1) << maxEigString << " (cached with matrix) = " << lambdaMax << std::endl;
        this->SetParameter(maxEigString, ParameterEntry(lambdaMax));
      }
    }

    // Calculate the eigenvalue ratio
    const Scalar defaultEigRatio = 20;

    Scalar ratio = defaultEigRatio;
    try {
      ratio = Teuchos::getValue<Scalar>(this->GetParameter(eigRatioString));

    } catch (Teuchos::Exceptions::InvalidParameterName&) {
      this->SetParameter(eigRatioString, ParameterEntry(ratio));
    }

    if (currentLevel.GetLevelID()) {
      // Update ratio to be
      //   ratio = max(number of fine DOFs / number of coarse DOFs, defaultValue)
      //
      // NOTE: We don't need to request previous level matrix as we know for sure it was constructed
      RCP<const Matrix> fineA = currentLevel.GetPreviousLevel()->Get<RCP<Matrix> >("A");
      size_t nRowsFine        = fineA->getGlobalNumRows();
      size_t nRowsCoarse      = A_->getGlobalNumRows();

      ratio = std::max(ratio, as<Scalar>(nRowsFine) / nRowsCoarse);

      this->GetOStream(Statistics1) << eigRatioString << " (computed) = " << ratio << std::endl;
      this->SetParameter(eigRatioString, ParameterEntry(ratio));
    }
  }  // if (type_ == "Chebyshev")

  if (type_ == "LINESMOOTHING_BANDED_RELAXATION" ||
      type_ == "LINESMOOTHING_BANDED RELAXATION" ||
      type_ == "LINESMOOTHING_BANDEDRELAXATION" ||
      type_ == "LINESMOOTHING_BLOCK_RELAXATION" ||
      type_ == "LINESMOOTHING_BLOCK RELAXATION" ||
      type_ == "LINESMOOTHING_BLOCKRELAXATION") {
    ParameterList& myparamList = const_cast<ParameterList&>(this->GetParameterList());

    LO CoarseNumZLayers = currentLevel.Get<LO>("CoarseNumZLayers", Factory::GetFactory("CoarseNumZLayers").get());
    if (CoarseNumZLayers > 0) {
      Teuchos::ArrayRCP<LO> TVertLineIdSmoo = currentLevel.Get<Teuchos::ArrayRCP<LO> >("LineDetection_VertLineIds", Factory::GetFactory("LineDetection_VertLineIds").get());

      // determine number of local parts
      LO maxPart = 0;
      for (size_t k = 0; k < Teuchos::as<size_t>(TVertLineIdSmoo.size()); k++) {
        if (maxPart < TVertLineIdSmoo[k]) maxPart = TVertLineIdSmoo[k];
      }

      size_t numLocalRows = A_->getLocalNumRows();
      TEUCHOS_TEST_FOR_EXCEPTION(numLocalRows % TVertLineIdSmoo.size() != 0, Exceptions::RuntimeError, "MueLu::Ifpack2Smoother::Setup(): the number of local nodes is incompatible with the TVertLineIdsSmoo.");

      if (numLocalRows == Teuchos::as<size_t>(TVertLineIdSmoo.size())) {
        myparamList.set("partitioner: type", "user");
        myparamList.set("partitioner: map", &(TVertLineIdSmoo[0]));
        myparamList.set("partitioner: local parts", maxPart + 1);
      } else {
        // we assume a constant number of DOFs per node
        size_t numDofsPerNode = numLocalRows / TVertLineIdSmoo.size();

        // Create a new Teuchos::ArrayRCP<LO> of size numLocalRows and fill it with the corresponding information
        Teuchos::ArrayRCP<LO> partitionerMap(numLocalRows, Teuchos::OrdinalTraits<LocalOrdinal>::invalid());
        for (size_t blockRow = 0; blockRow < Teuchos::as<size_t>(TVertLineIdSmoo.size()); ++blockRow)
          for (size_t dof = 0; dof < numDofsPerNode; dof++)
            partitionerMap[blockRow * numDofsPerNode + dof] = TVertLineIdSmoo[blockRow];
        myparamList.set("partitioner: type", "user");
        myparamList.set("partitioner: map", &(partitionerMap[0]));
        myparamList.set("partitioner: local parts", maxPart + 1);
      }

      if (type_ == "LINESMOOTHING_BANDED_RELAXATION" ||
          type_ == "LINESMOOTHING_BANDED RELAXATION" ||
          type_ == "LINESMOOTHING_BANDEDRELAXATION")
        type_ = "block relaxation";
      else
        type_ = "block relaxation";
    } else {
      // line detection failed -> fallback to point-wise relaxation
      this->GetOStream(Runtime0) << "Line detection failed: fall back to point-wise relaxation" << std::endl;
      myparamList.remove("partitioner: type", false);
      myparamList.remove("partitioner: map", false);
      myparamList.remove("partitioner: local parts", false);
      type_ = "point relaxation stand-alone";
    }

  }  // if (type_ == "LINESMOOTHING_BANDEDRELAXATION")

  if (type_ == "AGGREGATE") {
    SetupAggregate(currentLevel);
  }

  else {
    // If we're using a linear partitioner and haven't set the # local parts, set it to match the operator's block size
    ParameterList precList = this->GetParameterList();
    if (precList.isParameter("partitioner: type") && precList.get<std::string>("partitioner: type") == "linear" &&
        !precList.isParameter("partitioner: local parts")) {
      precList.set("partitioner: local parts", (int)A_->getLocalNumRows() / A_->GetFixedBlockSize());
    }

    RCP<Epetra_CrsMatrix> epA = Utilities::Op2NonConstEpetraCrs(A_);

    Ifpack factory;
    prec_ = rcp(factory.Create(type_, &(*epA), overlap_));
    TEUCHOS_TEST_FOR_EXCEPTION(prec_.is_null(), Exceptions::RuntimeError, "Could not create an Ifpack preconditioner with type = \"" << type_ << "\"");
    SetPrecParameters();
    prec_->Compute();
  }

  SmootherPrototype::IsSetup(true);

  if (type_ == "Chebyshev" && lambdaMax == -1.0) {
    Teuchos::RCP<Ifpack_Chebyshev> chebyPrec = rcp_dynamic_cast<Ifpack_Chebyshev>(prec_);
    if (chebyPrec != Teuchos::null) {
      lambdaMax = chebyPrec->GetLambdaMax();
      A_->SetMaxEigenvalueEstimate(lambdaMax);
      this->GetOStream(Statistics1) << "chebyshev: max eigenvalue (calculated by Ifpack)"
                                    << " = " << lambdaMax << std::endl;
    }
    TEUCHOS_TEST_FOR_EXCEPTION(lambdaMax == -1.0, Exceptions::RuntimeError, "MueLu::IfpackSmoother::Setup(): no maximum eigenvalue estimate");
  }

  this->GetOStream(Statistics1) << description() << std::endl;
}

template <class Node>
void IfpackSmoother<Node>::SetupAggregate(Level& currentLevel) {
  ParameterList& paramList = const_cast<ParameterList&>(this->GetParameterList());

  if (this->IsSetup() == true) {
    this->GetOStream(Warnings0) << "MueLu::Ifpack2moother::SetupAggregate(): Setup() has already been called" << std::endl;
    this->GetOStream(Warnings0) << "MueLu::IfpackSmoother::SetupAggregate(): reuse of this type is not available, reverting to full construction" << std::endl;
  }

  this->GetOStream(Statistics0) << "IfpackSmoother: Using Aggregate Smoothing" << std::endl;

  RCP<Aggregates> aggregates            = Factory::Get<RCP<Aggregates> >(currentLevel, "Aggregates");
  RCP<const LOMultiVector> vertex2AggId = aggregates->GetVertex2AggId();
  ArrayRCP<LO> aggregate_ids            = rcp_const_cast<LOMultiVector>(vertex2AggId)->getDataNonConst(0);
  ArrayRCP<LO> dof_ids;

  // We need to unamalgamate, if the FixedBlockSize > 1
  if (A_->GetFixedBlockSize() > 1) {
    // NOTE: We're basically going to have to leave a deallocated pointer hanging out
    // in the paramList object (and inside the partitioner).  This never gets
    // use again after Compute() gets called, so this is OK, but I'm still leaving
    // this note here in case it bites us again later.
    LO blocksize = (LO)A_->GetFixedBlockSize();
    dof_ids.resize(aggregate_ids.size() * blocksize);
    for (LO i = 0; i < (LO)aggregate_ids.size(); i++) {
      for (LO j = 0; j < (LO)blocksize; j++)
        dof_ids[i * blocksize + j] = aggregate_ids[i];
    }
  } else {
    dof_ids = aggregate_ids;
  }

  paramList.set("partitioner: map", dof_ids.getRawPtr());
  paramList.set("partitioner: type", "user");
  paramList.set("partitioner: overlap", 0);
  paramList.set("partitioner: local parts", (int)aggregates->GetNumAggregates());
  // In case of Dirichlet nodes
  paramList.set("partitioner: keep singletons", true);

  RCP<Epetra_CrsMatrix> A = Utilities::Op2NonConstEpetraCrs(A_);
  type_                   = "block relaxation stand-alone";

  Ifpack factory;
  prec_ = rcp(factory.Create(type_, &(*A), overlap_));
  TEUCHOS_TEST_FOR_EXCEPTION(prec_.is_null(), Exceptions::RuntimeError, "Could not create an Ifpack preconditioner with type = \"" << type_ << "\"");
  SetPrecParameters();

  int rv = prec_->Compute();
  TEUCHOS_TEST_FOR_EXCEPTION(rv, Exceptions::RuntimeError, "Ifpack preconditioner with type = \"" << type_ << "\" Compute() call failed.");
}

template <class Node>
void IfpackSmoother<Node>::Apply(MultiVector& X, const MultiVector& B, bool InitialGuessIsZero) const {
  TEUCHOS_TEST_FOR_EXCEPTION(SmootherPrototype::IsSetup() == false, Exceptions::RuntimeError, "MueLu::IfpackSmoother::Apply(): Setup() has not been called");

  // Forward the InitialGuessIsZero option to Ifpack
  Teuchos::ParameterList paramList;
  bool supportInitialGuess = false;
  if (type_ == "Chebyshev") {
    paramList.set("chebyshev: zero starting solution", InitialGuessIsZero);
    supportInitialGuess = true;

  } else if (type_ == "point relaxation stand-alone") {
    paramList.set("relaxation: zero starting solution", InitialGuessIsZero);
    supportInitialGuess = true;
  }

  SetPrecParameters(paramList);

  // Apply
  if (InitialGuessIsZero || supportInitialGuess) {
    Epetra_MultiVector& epX       = Utilities::MV2NonConstEpetraMV(X);
    const Epetra_MultiVector& epB = Utilities::MV2EpetraMV(B);

    prec_->ApplyInverse(epB, epX);

  } else {
    RCP<MultiVector> Residual   = Utilities::Residual(*A_, X, B);
    RCP<MultiVector> Correction = MultiVectorFactory::Build(A_->getDomainMap(), X.getNumVectors());

    Epetra_MultiVector& epX       = Utilities::MV2NonConstEpetraMV(*Correction);
    const Epetra_MultiVector& epB = Utilities::MV2EpetraMV(*Residual);

    prec_->ApplyInverse(epB, epX);

    X.update(1.0, *Correction, 1.0);
  }
}

template <class Node>
RCP<MueLu::SmootherPrototype<double, int, int, Node> > IfpackSmoother<Node>::Copy() const {
  RCP<IfpackSmoother<Node> > smoother = rcp(new IfpackSmoother<Node>(*this));
  smoother->SetParameterList(this->GetParameterList());
  return Teuchos::rcp_dynamic_cast<MueLu::SmootherPrototype<double, int, int, Node> >(smoother);
}

template <class Node>
std::string IfpackSmoother<Node>::description() const {
  std::ostringstream out;
  // The check "GetVerbLevel() == Test" is to avoid
  // failures in the EasyInterface test.
  if (prec_ == Teuchos::null || this->GetVerbLevel() == InterfaceTest) {
    out << SmootherPrototype::description();
    out << "{type = " << type_ << "}";
  } else {
    out << prec_->Label();
  }
  return out.str();
}

template <class Node>
void IfpackSmoother<Node>::print(Teuchos::FancyOStream& out, const VerbLevel verbLevel) const {
  MUELU_DESCRIBE;

  if (verbLevel & Parameters0)
    out0 << "Prec. type: " << type_ << std::endl;

  if (verbLevel & Parameters1) {
    out0 << "Parameter list: " << std::endl;
    Teuchos::OSTab tab2(out);
    out << this->GetParameterList();
    out0 << "Overlap: " << overlap_ << std::endl;
  }

  if (verbLevel & External)
    if (prec_ != Teuchos::null) {
      Teuchos::OSTab tab2(out);
      out << *prec_ << std::endl;
    }

  if (verbLevel & Debug) {
    out0 << "IsSetup: " << Teuchos::toString(SmootherPrototype::IsSetup()) << std::endl
         << "-" << std::endl
         << "RCP<A_>: " << A_ << std::endl
         << "RCP<prec_>: " << prec_ << std::endl;
  }
}

template <class Node>
size_t IfpackSmoother<Node>::getNodeSmootherComplexity() const {
  // FIXME: This is a placeholder
  return Teuchos::OrdinalTraits<size_t>::invalid();
}

}  // namespace MueLu

// The IfpackSmoother is only templated on the Node, since it is an Epetra only object
// Therefore we do not need the full ETI instantiations as we do for the other MueLu
// objects which are instantiated on all template parameters.
#if defined(HAVE_MUELU_EPETRA)
template class MueLu::IfpackSmoother<Xpetra::EpetraNode>;
#endif

#endif