MueLu_ScaledNullspaceFactory_def.hpp

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#ifndef MUELU_SCALEDNULLSPACEFACTORY_DEF_HPP
#define MUELU_SCALEDNULLSPACEFACTORY_DEF_HPP

#include <Xpetra_Matrix.hpp>
#include <Xpetra_MatrixUtils.hpp>
#include <Xpetra_MultiVectorFactory.hpp>
#include <Xpetra_BlockedMultiVector.hpp>
#include <Xpetra_VectorFactory.hpp>

#include "MueLu_ScaledNullspaceFactory_decl.hpp"
#include "MueLu_Level.hpp"
#include "MueLu_Monitor.hpp"

namespace MueLu {

  template <class Scalar, class LocalOrdinal, class GlobalOrdinal, class Node>
  RCP<const ParameterList> ScaledNullspaceFactory<Scalar, LocalOrdinal, GlobalOrdinal, Node>::GetValidParameterList() const {
    RCP<ParameterList> validParamList = rcp(new ParameterList());
    validParamList->set< std::string >("Fine level nullspace", "Nullspace", "Variable name which is used to store null space multi vector on the finest level (default=\"Nullspace\").");
  
    validParamList->set< RCP<const FactoryBase> >("A",                          Teuchos::null, "Generating factory of the fine level matrix (only needed if default null space is generated)");
    validParamList->set< RCP<const FactoryBase> >("Nullspace",                  Teuchos::null, "Generating factory of the fine level null space");

    return validParamList;
  }

  template <class Scalar, class LocalOrdinal, class GlobalOrdinal, class Node>
  void ScaledNullspaceFactory<Scalar, LocalOrdinal, GlobalOrdinal, Node>::DeclareInput(Level &currentLevel) const {
    // Scaled Nullspace always needs A & a Nullspace from somewhere
    Input(currentLevel, "A");
    Input(currentLevel, "Nullspace");
  }

  template <class Scalar, class LocalOrdinal, class GlobalOrdinal, class Node>
  void ScaledNullspaceFactory<Scalar, LocalOrdinal, GlobalOrdinal, Node>::Build(Level &currentLevel) const {
    FactoryMonitor m(*this, "Build", currentLevel);

    RCP<MultiVector> nullspace, tentativeNullspace;

    //TEUCHOS_TEST_FOR_EXCEPTION(currentLevel.GetLevelID() != 0, Exceptions::RuntimeError, "MueLu::ScaledNullspaceFactory::Build(): ScaledNullspaceFactory can be used for finest level (LevelID == 0) only.");

    if (currentLevel.GetLevelID() == 0) {
      if (currentLevel.IsAvailable("Nullspace", NoFactory::get())) {
        // When a fine nullspace have already been defined by user using Set("Nullspace", ...) or
        // Set("Nullspace1", ...), we use it.
        tentativeNullspace = currentLevel.Get< RCP<MultiVector> >("Nullspace", NoFactory::get());
      } else {
        // A User "Nullspace" (nspName) is not available (use factory)
        tentativeNullspace = currentLevel.Get< RCP<MultiVector> >("Nullspace", GetFactory("Nullspace").get()); 

      } // end if "Nullspace" not available
    } else {
      tentativeNullspace = currentLevel.Get< RCP<MultiVector> >("Nullspace", GetFactory("Nullspace").get()); 
    }

  
    // Scale!
    RCP<Matrix> A = Get< RCP<Matrix> >(currentLevel, "A");
    
    // determine numPDEs
    LocalOrdinal numPDEs = 1;
    if(A->IsView("stridedMaps")==true) {
      Xpetra::viewLabel_t oldView = A->SwitchToView("stridedMaps"); // note: "stridedMaps are always non-overlapping (correspond to range and domain maps!)
      TEUCHOS_TEST_FOR_EXCEPTION(Teuchos::rcp_dynamic_cast<const StridedMap>(A->getRowMap()) == Teuchos::null, Exceptions::BadCast, "MueLu::ScaledNullspaceFactory::Build: cast to strided row map failed.");
      numPDEs = Teuchos::rcp_dynamic_cast<const StridedMap>(A->getRowMap())->getFixedBlockSize();
      oldView = A->SwitchToView(oldView);
    }
   
    GetOStream(Runtime1) << "ScaledNullspaceFactory: Generating scaled nullspace, blocksize = "<< tentativeNullspace->getNumVectors() <<std::endl;
    nullspace = MultiVectorFactory::Build(tentativeNullspace->getMap(), tentativeNullspace->getNumVectors());  
    *nullspace = *tentativeNullspace;  // Copy the tentative nullspace
    RCP<MultiVector> blockDiagonal = MultiVectorFactory::Build(A->getDomainMap(), numPDEs);
    
    Xpetra::MatrixUtils<Scalar,LocalOrdinal,GlobalOrdinal,Node>::extractBlockDiagonal(*A,*blockDiagonal);
    Xpetra::MatrixUtils<Scalar,LocalOrdinal,GlobalOrdinal,Node>::inverseScaleBlockDiagonal(*blockDiagonal,true,*nullspace);

    // provide "Scaled Nullspace" variable on current level (used by TentativePFactory)
    Set(currentLevel, "Scaled Nullspace", nullspace);

  } // Build

} //namespace MueLu

#endif // MUELU_SCALEDNULLSPACEFACTORY_DEF_HPP