MueLu_NullspaceFactory_def.hpp

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#ifndef MUELU_NULLSPACEFACTORY_DEF_HPP
#define MUELU_NULLSPACEFACTORY_DEF_HPP

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

#include "MueLu_NullspaceFactory_decl.hpp"
#include "MueLu_Level.hpp"
#include "MueLu_Monitor.hpp"

namespace MueLu {

  template <class Scalar, class LocalOrdinal, class GlobalOrdinal, class Node>
  RCP<const ParameterList> NullspaceFactory<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\"). For block matrices also \"Nullspace1\" to \"Nullspace9\" are accepted to describe the null space vectors for the (i,i) block (i=1..9).");

    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");

    // TODO not very elegant.
    // 1/20/2016: we could add a sublist (e.g. "Nullspaces" which is excluded from parameter validation)
    validParamList->set< RCP<const FactoryBase> >("Nullspace1", Teuchos::null, "Generating factory of the fine level null space associated with the (1,1) block in your n x n block matrix.");
    validParamList->set< RCP<const FactoryBase> >("Nullspace2", Teuchos::null, "Generating factory of the fine level null space associated with the (2,2) block in your n x n block matrix.");
    validParamList->set< RCP<const FactoryBase> >("Nullspace3", Teuchos::null, "Generating factory of the fine level null space associated with the (3,3) block in your n x n block matrix.");
    validParamList->set< RCP<const FactoryBase> >("Nullspace4", Teuchos::null, "Generating factory of the fine level null space associated with the (4,4) block in your n x n block matrix.");
    validParamList->set< RCP<const FactoryBase> >("Nullspace5", Teuchos::null, "Generating factory of the fine level null space associated with the (5,5) block in your n x n block matrix.");
    validParamList->set< RCP<const FactoryBase> >("Nullspace6", Teuchos::null, "Generating factory of the fine level null space associated with the (6,6) block in your n x n block matrix.");
    validParamList->set< RCP<const FactoryBase> >("Nullspace7", Teuchos::null, "Generating factory of the fine level null space associated with the (7,7) block in your n x n block matrix.");
    validParamList->set< RCP<const FactoryBase> >("Nullspace8", Teuchos::null, "Generating factory of the fine level null space associated with the (8,8) block in your n x n block matrix.");
    validParamList->set< RCP<const FactoryBase> >("Nullspace9", Teuchos::null, "Generating factory of the fine level null space associated with the (9,9) block in your n x n block matrix.");

    return validParamList;
  }

  template <class Scalar, class LocalOrdinal, class GlobalOrdinal, class Node>
  void NullspaceFactory<Scalar, LocalOrdinal, GlobalOrdinal, Node>::DeclareInput(Level &currentLevel) const {

    const ParameterList & pL = GetParameterList();
    std::string nspName = pL.get<std::string>("Fine level nullspace");

    // only request "A" in DeclareInput if
    // 1) there is not nspName (e.g. "Nullspace") is available in Level, AND
    // 2) it is the finest level (i.e. LevelID == 0)
    if (currentLevel.IsAvailable(nspName, NoFactory::get()) == false && currentLevel.GetLevelID() == 0)
      Input(currentLevel, "A");

    if (currentLevel.GetLevelID() != 0) {
      // validate nullspaceFact_
      // 1) The factory for "Nullspace" (or nspName) must not be Teuchos::null, since the default factory
      //    for "Nullspace" is a NullspaceFactory
      // 2) The factory for "Nullspace" (or nspName) must be a TentativePFactory or any other TwoLevelFactoryBase derived object
      //    which generates the variable "Nullspace" as output
      TEUCHOS_TEST_FOR_EXCEPTION(GetFactory(nspName)==Teuchos::null, Exceptions::RuntimeError, "MueLu::NullspaceFactory::DeclareInput(): You must declare an existing factory which produces the variable \"Nullspace\" in the NullspaceFactory (e.g. a TentativePFactory).");
      currentLevel.DeclareInput("Nullspace", GetFactory(nspName).get(), this); /* ! "Nullspace" and nspName mismatch possible here */
    }
  }

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

    RCP<MultiVector> nullspace;

    //TEUCHOS_TEST_FOR_EXCEPTION(currentLevel.GetLevelID() != 0, Exceptions::RuntimeError, "MueLu::NullspaceFactory::Build(): NullspaceFactory can be used for finest level (LevelID == 0) only.");
    const ParameterList & pL = GetParameterList();
    std::string nspName = pL.get<std::string>("Fine level nullspace");

    if (currentLevel.GetLevelID() == 0) {

      if (currentLevel.IsAvailable(nspName, NoFactory::get())) {
        // When a fine nullspace have already been defined by user using Set("Nullspace", ...) or
        // Set("Nullspace1", ...), we use it.
        nullspace = currentLevel.Get< RCP<MultiVector> >(nspName, NoFactory::get());
        GetOStream(Runtime1) << "Use user-given nullspace " << nspName << ": nullspace dimension=" << nullspace->getNumVectors() << " nullspace length=" << nullspace->getGlobalLength() << std::endl;
      } else {
        // "Nullspace" (nspName) is not available
        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::CoalesceFactory::Build: cast to strided row map failed.");
          numPDEs = Teuchos::rcp_dynamic_cast<const StridedMap>(A->getRowMap())->getFixedBlockSize();
          oldView = A->SwitchToView(oldView);
        }

        GetOStream(Runtime1) << "Generating canonical nullspace: dimension = " << numPDEs << std::endl;
        nullspace = MultiVectorFactory::Build(A->getDomainMap(), numPDEs);

        RCP<BlockedMultiVector> bnsp = Teuchos::rcp_dynamic_cast<BlockedMultiVector>(nullspace);
        if(bnsp.is_null() == true) {
          for (int i=0; i<numPDEs; ++i) {
            ArrayRCP<Scalar> nsValues = nullspace->getDataNonConst(i);
            int numBlocks = nsValues.size() / numPDEs;
            for (int j=0; j< numBlocks; ++j) {
              nsValues[j*numPDEs + i] = 1.0;
            }
          }
        } else {
          fillNullspaceVector(bnsp,numPDEs);
        }
      } // end if "Nullspace" not available
    } else {
      // on coarser levels always use "Nullspace" as variable name, since it is expected by
      // tentative P factory to be "Nullspace"

      nullspace = currentLevel.Get< RCP<MultiVector> >("Nullspace", GetFactory(nspName).get()); /* ! "Nullspace" and nspName mismatch possible here */

    }

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

  } // Build

  template <class Scalar, class LocalOrdinal, class GlobalOrdinal, class Node>
  void NullspaceFactory<Scalar, LocalOrdinal, GlobalOrdinal, Node>::fillNullspaceVector(const RCP<BlockedMultiVector>& nsp, LocalOrdinal numPDEs) const {
    RCP< const BlockedMap> bmap = nsp->getBlockedMap();

    for(size_t r = 0; r < bmap->getNumMaps(); r++) {
      Teuchos::RCP<MultiVector> part = nsp->getMultiVector(r);
      Teuchos::RCP<BlockedMultiVector> bpart = Teuchos::rcp_dynamic_cast<BlockedMultiVector>(part);
      if(bpart.is_null() == true) {
        for (int i=0; i<numPDEs; ++i) {
          ArrayRCP<Scalar> nsValues = part->getDataNonConst(i);
          int numBlocks = nsValues.size() / numPDEs;
          for (int j=0; j< numBlocks; ++j) {
            nsValues[j*numPDEs + i] = 1.0;
          }
        }
      } else {
        // call this routine recursively
        fillNullspaceVector(bpart,numPDEs);
      }
    }
  }

} //namespace MueLu

#endif // MUELU_NULLSPACEFACTORY_DEF_HPP