MueLu_BraessSarazinSmoother_def.hpp

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#ifndef MUELU_BRAESSSARAZINSMOOTHER_DEF_HPP_
#define MUELU_BRAESSSARAZINSMOOTHER_DEF_HPP_
 
#include <Teuchos_ArrayViewDecl.hpp>
#include <Teuchos_ScalarTraits.hpp>
 
#include "MueLu_ConfigDefs.hpp"
 
#include <Xpetra_Matrix.hpp>
#include <Xpetra_BlockedCrsMatrix.hpp>
#include <Xpetra_MultiVectorFactory.hpp>
#include <Xpetra_VectorFactory.hpp>
#include <Xpetra_ReorderedBlockedCrsMatrix.hpp>
 
#include "MueLu_BraessSarazinSmoother_decl.hpp"
#include "MueLu_Level.hpp"
#include "MueLu_Utilities.hpp"
#include "MueLu_Monitor.hpp"
#include "MueLu_HierarchyUtils.hpp"
#include "MueLu_SmootherBase.hpp"
 
#include "MueLu_FactoryManager.hpp"
 
namespace MueLu {
 
  template <class Scalar,class LocalOrdinal, class GlobalOrdinal, class Node>
  void BraessSarazinSmoother<Scalar, LocalOrdinal, GlobalOrdinal, Node>::AddFactoryManager(RCP<const FactoryManagerBase> FactManager, int pos) {
    TEUCHOS_TEST_FOR_EXCEPTION(pos != 0, Exceptions::RuntimeError, "MueLu::BraessSarazinSmoother::AddFactoryManager: parameter \'pos\' must be zero! error.");
    FactManager_ = FactManager;
  }
 
  template <class Scalar, class LocalOrdinal, class GlobalOrdinal, class Node>
  RCP<const ParameterList> BraessSarazinSmoother<Scalar, LocalOrdinal, GlobalOrdinal, Node>::GetValidParameterList() const {
    RCP<ParameterList> validParamList = rcp(new ParameterList());
 
    SC one = Teuchos::ScalarTraits<SC>::one();
 
    validParamList->set<RCP<const FactoryBase> >("A", Teuchos::null, "Generating factory of the matrix A");
 
    validParamList->set<bool>("lumping", false, "Use lumping to construct diag(A(0,0)), "
        "i.e. use row sum of the abs values on the diagonal as approximation of A00 (and A00^{-1})");
    validParamList->set<SC>("Damping factor", one, "Damping/Scaling factor in BraessSarazin (usually has to be chosen > 1, default = 1.0)");
    validParamList->set<LO>("Sweeps", 1, "Number of BraessSarazin sweeps (default = 1)");
    validParamList->set<bool>("q2q1 mode", false, "Run in the mode matching Q2Q1 matlab code");
 
    return validParamList;
  }
 
  template <class Scalar,class LocalOrdinal, class GlobalOrdinal, class Node>
  void BraessSarazinSmoother<Scalar, LocalOrdinal, GlobalOrdinal, Node>::DeclareInput(Level& currentLevel) const {
    this->Input(currentLevel, "A");
 
    TEUCHOS_TEST_FOR_EXCEPTION(FactManager_.is_null(), Exceptions::RuntimeError,
                               "MueLu::BraessSarazinSmoother::DeclareInput: FactManager_ must not be null! "
                               "Introduce a FactoryManager for the SchurComplement equation.");
 
    // carefully call DeclareInput after switching to internal FactoryManager
    {
      SetFactoryManager currentSFM(rcpFromRef(currentLevel), FactManager_);
 
      // request "Smoother" for current subblock row.
      currentLevel.DeclareInput("PreSmoother", FactManager_->GetFactory("Smoother").get());
 
      // request Schur matrix just in case
      currentLevel.DeclareInput("A", FactManager_->GetFactory("A").get());
    }
  }
 
  template <class Scalar,class LocalOrdinal, class GlobalOrdinal, class Node>
  void BraessSarazinSmoother<Scalar, LocalOrdinal, GlobalOrdinal, Node>::Setup(Level& currentLevel) {
    FactoryMonitor m(*this, "Setup Smoother", currentLevel);
 
    if (SmootherPrototype::IsSetup() == true)
      this->GetOStream(Warnings0) << "MueLu::BreaessSarazinSmoother::Setup(): Setup() has already been called";
 
    // Extract blocked operator A from current level
    A_ = Factory::Get<RCP<Matrix> > (currentLevel, "A");
    RCP<BlockedCrsMatrix> bA = rcp_dynamic_cast<BlockedCrsMatrix>(A_);
    TEUCHOS_TEST_FOR_EXCEPTION(bA.is_null(), Exceptions::BadCast,
                               "MueLu::BraessSarazinSmoother::Setup: input matrix A is not of type BlockedCrsMatrix! error.");
 
    // Store map extractors
    rangeMapExtractor_  = bA->getRangeMapExtractor();
    domainMapExtractor_ = bA->getDomainMapExtractor();
 
    // Store the blocks in local member variables
    A00_ = bA->getMatrix(0,0);
    A01_ = bA->getMatrix(0,1);
    A10_ = bA->getMatrix(1,0);
    A11_ = bA->getMatrix(1,1);
 
    const ParameterList& pL = Factory::GetParameterList();
    SC omega = pL.get<SC>("Damping factor");
 
    // Create the inverse of the diagonal of F
    // TODO add safety check for zeros on diagonal of F!
    RCP<Vector> diagFVector = VectorFactory::Build(A00_->getRowMap());
    if (pL.get<bool>("lumping") == false) {
      A00_->getLocalDiagCopy(*diagFVector);       // extract diagonal of F
    } else {
      diagFVector = Utilities::GetLumpedMatrixDiagonal(*A00_);
    }
    diagFVector->scale(omega);
    D_ = Utilities::GetInverse(diagFVector);
 
    // check whether D_ is a blocked vector with only 1 block
    RCP<BlockedVector> bD = Teuchos::rcp_dynamic_cast<BlockedVector>(D_);
    if(bD.is_null() == false && bD->getBlockedMap()->getNumMaps() == 1) {
      RCP<Vector> nestedVec = bD->getMultiVector(0,bD->getBlockedMap()->getThyraMode())->getVectorNonConst(0);
      D_.swap(nestedVec);
    }
 
    // Set the Smoother
    // carefully switch to the SubFactoryManagers (defined by the users)
    {
      SetFactoryManager currentSFM(rcpFromRef(currentLevel), FactManager_);
      smoo_ = currentLevel.Get<RCP<SmootherBase> >("PreSmoother", FactManager_->GetFactory("Smoother").get());
      S_    = currentLevel.Get<RCP<Matrix> >      ("A",           FactManager_->GetFactory("A").get());
    }
 
    SmootherPrototype::IsSetup(true);
  }
 
  template <class Scalar,class LocalOrdinal, class GlobalOrdinal, class Node>
  void BraessSarazinSmoother<Scalar, LocalOrdinal, GlobalOrdinal, Node>::Apply(MultiVector& X, const MultiVector& B, bool InitialGuessIsZero) const {
    TEUCHOS_TEST_FOR_EXCEPTION(SmootherPrototype::IsSetup() == false, Exceptions::RuntimeError,
                               "MueLu::BraessSarazinSmoother::Apply(): Setup() has not been called");
 
    RCP<MultiVector> rcpX       = rcpFromRef(X);
    RCP<const MultiVector> rcpB = rcpFromRef(B);
 
    // make sure that both rcpX and rcpB are BlockedMultiVector objects
    bool bCopyResultX = false;
    RCP<BlockedCrsMatrix> bA = Teuchos::rcp_dynamic_cast<BlockedCrsMatrix>(A_);
    MUELU_TEST_FOR_EXCEPTION(bA.is_null() == true, Exceptions::RuntimeError, "MueLu::BlockedGaussSeidelSmoother::Apply(): A_ must be a BlockedCrsMatrix");
    RCP<BlockedMultiVector> bX = Teuchos::rcp_dynamic_cast<BlockedMultiVector>(rcpX);
    RCP<const BlockedMultiVector> bB = Teuchos::rcp_dynamic_cast<const BlockedMultiVector>(rcpB);
 
    if(bX.is_null() == true) {
      RCP<MultiVector> test = Teuchos::rcp(new BlockedMultiVector(bA->getBlockedDomainMap(),rcpX));
      rcpX.swap(test);
      bCopyResultX = true;
    }
 
    if(bB.is_null() == true) {
      RCP<const MultiVector> test = Teuchos::rcp(new BlockedMultiVector(bA->getBlockedRangeMap(),rcpB));
      rcpB.swap(test);
    }
 
    // we now can guarantee that X and B are blocked multi vectors
    bX = Teuchos::rcp_dynamic_cast<BlockedMultiVector>(rcpX);
    bB = Teuchos::rcp_dynamic_cast<const BlockedMultiVector>(rcpB);
 
    // check the type of operator
    RCP<Xpetra::ReorderedBlockedCrsMatrix<Scalar,LocalOrdinal,GlobalOrdinal,Node> > rbA = Teuchos::rcp_dynamic_cast<Xpetra::ReorderedBlockedCrsMatrix<Scalar,LocalOrdinal,GlobalOrdinal,Node> >(bA);
    if(rbA.is_null() == false) {
      // A is a ReorderedBlockedCrsMatrix
      Teuchos::RCP<const Xpetra::BlockReorderManager > brm = rbA->getBlockReorderManager();
 
      // check type of X vector
      if(bX->getBlockedMap()->getNumMaps() != bA->getDomainMapExtractor()->NumMaps()) {
        // X is a blocked multi vector but incompatible to the reordered blocked operator A
        Teuchos::RCP<MultiVector> test =
            buildReorderedBlockedMultiVector(brm, bX);
        rcpX.swap(test);
      }
      if(bB->getBlockedMap()->getNumMaps() != bA->getRangeMapExtractor()->NumMaps()) {
        // B is a blocked multi vector but incompatible to the reordered blocked operator A
        Teuchos::RCP<const MultiVector> test =
            buildReorderedBlockedMultiVector(brm, bB);
        rcpB.swap(test);
      }
    }
 
    // use the GIDs of the sub blocks
    // This is valid as the subblocks actually represent the GIDs (either Thyra, Xpetra or pseudo Xpetra)
 
    bool bRangeThyraMode  = rangeMapExtractor_->getThyraMode();
    bool bDomainThyraMode = domainMapExtractor_->getThyraMode();
 
    RCP<MultiVector> deltaX     = MultiVectorFactory::Build(rcpX->getMap(), rcpX->getNumVectors());
    RCP<BlockedMultiVector> bdeltaX = Teuchos::rcp_dynamic_cast<BlockedMultiVector>(deltaX);
    RCP<MultiVector> deltaX0 = bdeltaX->getMultiVector(0,bDomainThyraMode);
    RCP<MultiVector> deltaX1 = bdeltaX->getMultiVector(1,bDomainThyraMode);
 
    RCP<MultiVector> Rtmp    = rangeMapExtractor_->getVector(1, rcpB->getNumVectors(), bRangeThyraMode);
 
 
    typedef Teuchos::ScalarTraits<SC> STS;
    SC one = STS::one(), zero = STS::zero();
 
    // extract parameters from internal parameter list
    const ParameterList& pL = Factory::GetParameterList();
    LO nSweeps = pL.get<LO>("Sweeps");
 
    RCP<MultiVector> R;// = MultiVectorFactory::Build(rcpB->getMap(), rcpB->getNumVectors());;
    if (InitialGuessIsZero)  {
      R = MultiVectorFactory::Build(rcpB->getMap(), rcpB->getNumVectors());
      R->update(one, *rcpB, zero);
    } else {
      R = Utilities::Residual(*A_, *rcpX, *rcpB);
    }
 
    // extract diagonal of Schur complement operator
    RCP<Vector> diagSVector = VectorFactory::Build(S_->getRowMap());
    S_->getLocalDiagCopy(*diagSVector);
 
    for (LO run = 0; run < nSweeps; ++run) {
      // Extract corresponding subvectors from X and R
      // Automatically detect whether we use Thyra or Xpetra GIDs
      // The GIDs should be always compatible with the GIDs of A00, A01, etc...
      RCP<MultiVector> R0 = rangeMapExtractor_ ->ExtractVector(R, 0, bRangeThyraMode);
      RCP<MultiVector> R1 = rangeMapExtractor_ ->ExtractVector(R, 1, bRangeThyraMode);
 
      // Calculate Rtmp = R1 - D * deltaX0 (equation 8.14)
      deltaX0->putScalar(zero);
      deltaX0->elementWiseMultiply(one, *D_, *R0, zero);    // deltaX0 = D * R0 (equation 8.13)
      A10_->apply(*deltaX0, *Rtmp);                         // Rtmp    = A10*D*deltaX0 (intermediate step)
      Rtmp->update(one, *R1, -one);                         // Rtmp    = R1 - A10*D*deltaX0
 
      if (!pL.get<bool>("q2q1 mode")) {
        deltaX1->putScalar(zero);
      } else {
        // special code for q2q1
        if(Teuchos::rcp_dynamic_cast<BlockedVector>(diagSVector) == Teuchos::null) {
          ArrayRCP<SC> Sdiag = diagSVector->getDataNonConst(0);
          ArrayRCP<SC> deltaX1data = deltaX1->getDataNonConst(0);
          ArrayRCP<SC> Rtmpdata    = Rtmp->getDataNonConst(0);
          for (GO row = 0; row < deltaX1data.size(); row++)
            deltaX1data[row] = Teuchos::as<SC>(1.1)*Rtmpdata[row] / Sdiag[row];
        } else {
          TEUCHOS_TEST_FOR_EXCEPTION(true,MueLu::Exceptions::RuntimeError,"MueLu::BraessSarazinSmoother: q2q1 mode only supported for non-blocked operators.")
        }
      }
 
      smoo_->Apply(*deltaX1,*Rtmp);
 
      // Compute deltaX0
      deltaX0->putScalar(zero);                             // just for safety
      A01_->apply(*deltaX1, *deltaX0);                      // deltaX0 = A01*deltaX1
      deltaX0->update(one, *R0, -one);                      // deltaX0 = R0 - A01*deltaX1
      R0.swap(deltaX0);
      deltaX0->elementWiseMultiply(one, *D_, *R0, zero);    // deltaX0 = D*(R0 - A01*deltaX1)
 
      RCP<MultiVector> X0 = domainMapExtractor_->ExtractVector(rcpX, 0, bDomainThyraMode);
      RCP<MultiVector> X1 = domainMapExtractor_->ExtractVector(rcpX, 1, bDomainThyraMode);
 
      // Update solution
      X0->update(one, *deltaX0, one);
      X1->update(one, *deltaX1, one);
 
      domainMapExtractor_->InsertVector(X0, 0, rcpX, bDomainThyraMode);
      domainMapExtractor_->InsertVector(X1, 1, rcpX, bDomainThyraMode);
 
      if (run < nSweeps-1) {
        R = Utilities::Residual(*A_, *rcpX, *rcpB);
      }
 
    }
 
    if (bCopyResultX == true) {
      RCP<MultiVector> Xmerged = bX->Merge();
      X.update(one, *Xmerged, zero);
    }
 
  }
 
  template <class Scalar,class LocalOrdinal, class GlobalOrdinal, class Node>
  RCP<MueLu::SmootherPrototype<Scalar, LocalOrdinal, GlobalOrdinal, Node> >
  BraessSarazinSmoother<Scalar, LocalOrdinal, GlobalOrdinal, Node>::Copy () const {
    return rcp (new BraessSarazinSmoother (*this));
  }
 
  template <class Scalar,class LocalOrdinal, class GlobalOrdinal, class Node>
  std::string BraessSarazinSmoother<Scalar, LocalOrdinal, GlobalOrdinal, Node>::
  description () const {
    std::ostringstream out;
    out << SmootherPrototype::description();
    out << "{type = " << type_ << "}";
    return out.str();
  }
 
  template <class Scalar,class LocalOrdinal, class GlobalOrdinal, class Node>
  void BraessSarazinSmoother<Scalar, LocalOrdinal, GlobalOrdinal, Node>::print(Teuchos::FancyOStream &out, const VerbLevel verbLevel) const {
    MUELU_DESCRIBE;
 
    if (verbLevel & Parameters0) {
      out0 << "Prec. type: " << type_ << /*" Sweeps: " << nSweeps_ << " damping: " << omega_ <<*/ std::endl;
    }
 
    if (verbLevel & Debug) {
      out0 << "IsSetup: " << Teuchos::toString(SmootherPrototype::IsSetup()) << std::endl;
    }
  }
 
  template <class Scalar,class LocalOrdinal, class GlobalOrdinal, class Node>
  size_t BraessSarazinSmoother<Scalar, LocalOrdinal, GlobalOrdinal, Node>::getNodeSmootherComplexity() const {
    // FIXME: This is a placeholder
    return Teuchos::OrdinalTraits<size_t>::invalid();
  }
 
} // namespace MueLu
 
#endif /* MUELU_BRAESSSARAZINSMOOTHER_DEF_HPP_ */