MueLu_DropNegativeEntriesFactory_def.hpp

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#ifndef MUELU_DROPNEGATIVEENTRIESFACTORY_DEF_HPP
#define MUELU_DROPNEGATIVEENTRIESFACTORY_DEF_HPP

#include <Xpetra_CrsGraph.hpp>
#include <Xpetra_Matrix.hpp>
#include <Xpetra_Vector.hpp>
#include <Xpetra_MatrixFactory.hpp>
#include <Xpetra_CrsGraphFactory.hpp>

#include "MueLu_DropNegativeEntriesFactory_decl.hpp"

#include "MueLu_FactoryManager.hpp"
#include "MueLu_Level.hpp"
#include "MueLu_GraphBase.hpp"
#include "MueLu_Graph.hpp"
#include "MueLu_Monitor.hpp"

namespace MueLu {

  template <class Scalar, class LocalOrdinal, class GlobalOrdinal, class Node>
  RCP<const ParameterList> DropNegativeEntriesFactory<Scalar, LocalOrdinal, GlobalOrdinal, Node>::GetValidParameterList() const {
    RCP<ParameterList> validParamList = rcp(new ParameterList());

#define SET_VALID_ENTRY(name) validParamList->setEntry(name, MasterList::getEntry(name))
#undef  SET_VALID_ENTRY

    validParamList->set< RCP<const FactoryBase> >("A",              Teuchos::null, "Generating factory of the matrix A used for filtering");

    return validParamList;
  }

  template <class Scalar, class LocalOrdinal, class GlobalOrdinal, class Node>
  void DropNegativeEntriesFactory<Scalar, LocalOrdinal, GlobalOrdinal, Node>::DeclareInput(Level& currentLevel) const {
    Input(currentLevel, "A");
  }

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

    RCP<Matrix> Ain = Get< RCP<Matrix> >(currentLevel, "A");

    LocalOrdinal nDofsPerNode = Ain->GetFixedBlockSize();

    // create new empty Operator
    Teuchos::RCP<Matrix> Aout = MatrixFactory::Build(Ain->getRowMap(), Ain->getGlobalMaxNumRowEntries());

    size_t numLocalRows = Ain->getNodeNumRows();
    for(size_t row=0; row<numLocalRows; row++) {
      GlobalOrdinal grid = Ain->getRowMap()->getGlobalElement(row);

      int rDofID = Teuchos::as<int>(grid % nDofsPerNode);

      // extract row information from input matrix
      Teuchos::ArrayView<const LocalOrdinal> indices;
      Teuchos::ArrayView<const Scalar> vals;
      Ain->getLocalRowView(row, indices, vals);

      // just copy all values in output
      Teuchos::ArrayRCP<GlobalOrdinal> indout(indices.size(),Teuchos::ScalarTraits<GlobalOrdinal>::zero());
      Teuchos::ArrayRCP<Scalar>        valout(indices.size(),Teuchos::ScalarTraits<Scalar>::zero());

      size_t nNonzeros = 0;
      for(size_t i=0; i<(size_t)indices.size(); i++) {
        GlobalOrdinal gcid = Ain->getColMap()->getGlobalElement(indices[i]); // global column id

        int cDofID = Teuchos::as<int>(gcid % nDofsPerNode);
        if(rDofID == cDofID && Teuchos::ScalarTraits<Scalar>::magnitude(vals[i]) >= Teuchos::ScalarTraits<Scalar>::magnitude(Teuchos::ScalarTraits<Scalar>::zero())) {
          indout [nNonzeros] = gcid;
          valout [nNonzeros] = vals[i];
          nNonzeros++;
        }
      }
      indout.resize(nNonzeros);
      valout.resize(nNonzeros);

      Aout->insertGlobalValues(Ain->getRowMap()->getGlobalElement(row), indout.view(0,indout.size()), valout.view(0,valout.size()));
    }

    Aout->fillComplete(Ain->getDomainMap(), Ain->getRangeMap());

    // copy block size information
    Aout->SetFixedBlockSize(nDofsPerNode);

    GetOStream(Statistics0, 0) << "Nonzeros in A (input): " << Ain->getGlobalNumEntries() << ", Nonzeros after filtering A: " << Aout->getGlobalNumEntries() << std::endl;

    Set(currentLevel, "A", Aout);
  }

} //namespace MueLu

#endif // MUELU_DROPNEGATIVEENTRIESFACTORY_DEF_HPP