Panzer_L2Projection.cpp

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// @HEADER
// @HEADER
 
#ifndef PANZER_L2_PROJECTION_IMPL_HPP
#define PANZER_L2_PROJECTION_IMPL_HPP
 
#include "Teuchos_DefaultMpiComm.hpp"
#include "Tpetra_CrsGraph.hpp"
#include "Tpetra_MultiVector.hpp"
#include "Tpetra_CrsMatrix.hpp"
#include "Panzer_L2Projection.hpp"
#include "Panzer_BasisDescriptor.hpp"
#include "Panzer_TpetraLinearObjContainer.hpp"
#include "Panzer_TpetraLinearObjFactory.hpp"
#include "Panzer_BlockedTpetraLinearObjFactory.hpp"
#include "Panzer_ElementBlockIdToPhysicsIdMap.hpp"
#include "Panzer_DOFManagerFactory.hpp"
#include "Panzer_BlockedDOFManagerFactory.hpp"
#include "Panzer_IntrepidFieldPattern.hpp"
#include "Panzer_WorksetDescriptor.hpp"
#include "Panzer_WorksetContainer.hpp"
#include "Panzer_Workset.hpp"
 
namespace panzer {
 
  void panzer::L2Projection::setup(const panzer::BasisDescriptor& targetBasis,
                                   const panzer::IntegrationDescriptor& integrationDescriptor,
                                   const Teuchos::RCP<const Teuchos::MpiComm<int>>& comm,
                                   const Teuchos::RCP<const panzer::ConnManager>& connManager,
                                   const std::vector<std::string>& elementBlockNames,
                                   const Teuchos::RCP<panzer::WorksetContainer> worksetContainer)
  {
    targetBasisDescriptor_ = targetBasis;
    integrationDescriptor_ = integrationDescriptor;
    comm_ = comm;
    connManager_ = connManager;
    elementBlockNames_ = elementBlockNames;
    worksetContainer_ = worksetContainer;
    setupCalled_ = true;
 
    // Build target DOF Manager
    targetGlobalIndexer_ =
      Teuchos::rcp(new panzer::DOFManager(Teuchos::rcp_const_cast<panzer::ConnManager>(connManager),*(comm->getRawMpiComm())));
 
    // For hybrid mesh, blocks could have different topology
    for (const auto& eBlock : elementBlockNames_) {
      std::vector<shards::CellTopology> topologies;
      connManager_->getElementBlockTopologies(topologies);
      std::vector<std::string> ebNames;
      connManager_->getElementBlockIds(ebNames);
      const auto search = std::find(ebNames.cbegin(),ebNames.cend(),eBlock);
      TEUCHOS_ASSERT(search != ebNames.cend());
      const int index = std::distance(ebNames.cbegin(),search);
      const auto& cellTopology = topologies[index];
 
      auto intrepidBasis = panzer::createIntrepid2Basis<PHX::Device,double,double>(targetBasisDescriptor_.getType(),
                                                                                   targetBasisDescriptor_.getOrder(),
                                                                                   cellTopology);
      Teuchos::RCP<const panzer::FieldPattern> fieldPattern(new panzer::Intrepid2FieldPattern(intrepidBasis));
      // Field name is the basis type
      targetGlobalIndexer_->addField(eBlock,targetBasisDescriptor_.getType(),fieldPattern);
    }
 
    targetGlobalIndexer_->buildGlobalUnknowns();
 
    // Check workset needs are correct
  }
 
  Teuchos::RCP<panzer::GlobalIndexer>
  panzer::L2Projection::getTargetGlobalIndexer() const
  {return targetGlobalIndexer_;}
 
  Teuchos::RCP<Tpetra::CrsMatrix<double,panzer::LocalOrdinal,panzer::GlobalOrdinal,panzer::TpetraNodeType>>
  panzer::L2Projection::buildMassMatrix(bool use_lumping,
                                        const std::unordered_map<std::string,double>* elementBlockMultipliers)
  {
    PANZER_FUNC_TIME_MONITOR_DIFF("L2Projection::Build Mass Matrix",TopBuildMassMatrix);
    TEUCHOS_ASSERT(setupCalled_);
 
    if (elementBlockMultipliers != nullptr) {
      TEUCHOS_ASSERT(elementBlockMultipliers->size() == elementBlockNames_.size());
    }
 
    // Allocate the owned matrix
    std::vector<Teuchos::RCP<const panzer::GlobalIndexer>> indexers;
    indexers.push_back(targetGlobalIndexer_);
 
    panzer::BlockedTpetraLinearObjFactory<panzer::Traits,double,panzer::LocalOrdinal,panzer::GlobalOrdinal,panzer::TpetraNodeType> factory(comm_,indexers);
 
    auto ownedMatrix = factory.getTpetraMatrix(0,0);
    auto ghostedMatrix = factory.getGhostedTpetraMatrix(0,0);
    ownedMatrix->resumeFill();
    ownedMatrix->setAllToScalar(0.0);
    ghostedMatrix->resumeFill();
    ghostedMatrix->setAllToScalar(0.0);
    PHX::Device().fence();
 
    auto M = ghostedMatrix->getLocalMatrix();
    const int fieldIndex = targetGlobalIndexer_->getFieldNum(targetBasisDescriptor_.getType());
 
    const bool is_scalar = targetBasisDescriptor_.getType()=="HGrad" || targetBasisDescriptor_.getType()=="Const" || targetBasisDescriptor_.getType()=="HVol";
 
    // Loop over element blocks and fill mass matrix
    if(is_scalar){
      for (const auto& block : elementBlockNames_) {
 
        double ebMultiplier = 1.0;
        if (elementBlockMultipliers != nullptr)
          ebMultiplier = elementBlockMultipliers->find(block)->second;
 
        // Based on descriptor, currently assumes there should only be one workset
        panzer::WorksetDescriptor wd(block,panzer::WorksetSizeType::ALL_ELEMENTS,true,true);
        const auto worksets = worksetContainer_->getWorksets(wd);
 
        for (const auto& workset : *worksets) {
 
          const auto basisValues = workset.getBasisValues(targetBasisDescriptor_,integrationDescriptor_);
 
          const auto unweightedBasis = basisValues.basis_scalar;
          const auto weightedBasis = basisValues.weighted_basis_scalar;
 
          // Offsets (this assumes UVM, need to fix)
          const std::vector<panzer::LocalOrdinal>& offsets = targetGlobalIndexer_->getGIDFieldOffsets(block,fieldIndex);
          PHX::View<panzer::LocalOrdinal*> kOffsets("MassMatrix: Offsets",offsets.size());
          for(const auto& i : offsets)
            kOffsets(i) = offsets[i];
 
          PHX::Device().fence();
 
          // Local Ids
          Kokkos::View<panzer::LocalOrdinal**,PHX::Device> localIds("MassMatrix: LocalIds", workset.numOwnedCells()+workset.numGhostCells()+workset.numVirtualCells(),
                                                  targetGlobalIndexer_->getElementBlockGIDCount(block));
 
          // Remove the ghosted cell ids or the call to getElementLocalIds will spill array bounds
          const auto cellLocalIdsNoGhost = Kokkos::subview(workset.cell_local_ids_k,std::make_pair(0,workset.numOwnedCells()));
 
          targetGlobalIndexer_->getElementLIDs(cellLocalIdsNoGhost,localIds);
 
          const int numBasisPoints = static_cast<int>(weightedBasis.extent(1));
          if ( use_lumping ) {
            Kokkos::parallel_for(workset.numOwnedCells(),KOKKOS_LAMBDA (const int& cell) {
              double total_mass = 0.0, trace = 0.0;
 
              panzer::LocalOrdinal cLIDs[256];
              const int numIds = static_cast<int>(localIds.extent(1));
              for(int i=0;i<numIds;++i)
                cLIDs[i] = localIds(cell,i);
 
              double vals[256]={0.0};
              const int numQP = static_cast<int>(unweightedBasis.extent(2));
 
              for (int row=0; row < numBasisPoints; ++row) {
                for (int col=0; col < numIds; ++col) {
                  for (int qp=0; qp < numQP; ++qp) {
                    auto tmp = unweightedBasis(cell,row,qp) * weightedBasis(cell,col,qp) * ebMultiplier;
                    total_mass += tmp;
                    if (col == row )
                      trace += tmp;
                  }
                }
              }
 
              for (int row=0; row < numBasisPoints; ++row) {
                for (int col=0; col < numBasisPoints; ++col)
                  vals[col] = 0;
 
                int offset = kOffsets(row);
                panzer::LocalOrdinal lid = localIds(cell,offset);
                int col = row;
                vals[col] = 0.0;
                for (int qp=0; qp < numQP; ++qp)
                  vals[col] += unweightedBasis(cell,row,qp) * weightedBasis(cell,col,qp) * ebMultiplier * total_mass / trace;
 
                M.sumIntoValues(lid,cLIDs,numIds,vals,true,true);
              }
            });
 
          } else {
            Kokkos::parallel_for(workset.numOwnedCells(),KOKKOS_LAMBDA (const int& cell) {
 
              panzer::LocalOrdinal cLIDs[256];
              const int numIds = static_cast<int>(localIds.extent(1));
              for(int i=0;i<numIds;++i)
                cLIDs[i] = localIds(cell,i);
 
              double vals[256];
              const int numQP = static_cast<int>(unweightedBasis.extent(2));
 
              for (int row=0; row < numBasisPoints; ++row) {
                int offset = kOffsets(row);
                panzer::LocalOrdinal lid = localIds(cell,offset);
 
                for (int col=0; col < numIds; ++col) {
                  vals[col] = 0.0;
                  for (int qp=0; qp < numQP; ++qp)
                    vals[col] += unweightedBasis(cell,row,qp) * weightedBasis(cell,col,qp) * ebMultiplier;
                }
                M.sumIntoValues(lid,cLIDs,numIds,vals,true,true);
 
              }
 
            });
          }
        }
      }
    } else {
      for (const auto& block : elementBlockNames_) {
 
        double ebMultiplier = 1.0;
        if (elementBlockMultipliers != nullptr)
          ebMultiplier = elementBlockMultipliers->find(block)->second;
 
        // Based on descriptor, currently assumes there should only be one workset
        panzer::WorksetDescriptor wd(block,panzer::WorksetSizeType::ALL_ELEMENTS,true,true);
        const auto& worksets = worksetContainer_->getWorksets(wd);
 
        for (const auto& workset : *worksets) {
 
          const auto basisValues = workset.getBasisValues(targetBasisDescriptor_,integrationDescriptor_);
 
          const auto unweightedBasis = basisValues.basis_vector;
          const auto weightedBasis = basisValues.weighted_basis_vector;
 
          // Offsets (this assumes UVM, need to fix)
          const std::vector<panzer::LocalOrdinal>& offsets = targetGlobalIndexer_->getGIDFieldOffsets(block,fieldIndex);
          PHX::View<panzer::LocalOrdinal*> kOffsets("MassMatrix: Offsets",offsets.size());
          for(const auto& i : offsets)
            kOffsets(i) = offsets[i];
 
          PHX::Device().fence();
 
          // Local Ids
          Kokkos::View<panzer::LocalOrdinal**,PHX::Device> localIds("MassMatrix: LocalIds", workset.numOwnedCells()+workset.numGhostCells()+workset.numVirtualCells(),
                                                  targetGlobalIndexer_->getElementBlockGIDCount(block));
 
          // Remove the ghosted cell ids or the call to getElementLocalIds will spill array bounds
          const auto cellLocalIdsNoGhost = Kokkos::subview(workset.cell_local_ids_k,std::make_pair(0,workset.numOwnedCells()));
 
          targetGlobalIndexer_->getElementLIDs(cellLocalIdsNoGhost,localIds);
 
          const int numBasisPoints = static_cast<int>(weightedBasis.extent(1));
          Kokkos::parallel_for(workset.numOwnedCells(),KOKKOS_LAMBDA (const int& cell) {
 
            panzer::LocalOrdinal cLIDs[256];
            const int numIds = static_cast<int>(localIds.extent(1));
            for(int i=0;i<numIds;++i)
              cLIDs[i] = localIds(cell,i);
 
            double vals[256];
            const int numQP = static_cast<int>(unweightedBasis.extent(2));
 
            for (int qp=0; qp < numQP; ++qp) {
              for (int row=0; row < numBasisPoints; ++row) {
                int offset = kOffsets(row);
                panzer::LocalOrdinal lid = localIds(cell,offset);
 
                for (int col=0; col < numIds; ++col){
                  vals[col] = 0.0;
                  for(int dim=0; dim < static_cast<int>(weightedBasis.extent(3)); ++dim)
                    vals[col] += unweightedBasis(cell,row,qp,dim) * weightedBasis(cell,col,qp,dim) * ebMultiplier;
                }
 
                M.sumIntoValues(lid,cLIDs,numIds,vals,true,true);
              }
            }
 
          });
        }
      }
    }
    PHX::exec_space().fence();
 
    {
      PANZER_FUNC_TIME_MONITOR_DIFF("Exporting of mass matrix",ExportMM);
      auto map = factory.getMap(0);
      ghostedMatrix->fillComplete(map,map);
      const auto exporter = factory.getGhostedExport(0);
      ownedMatrix->doExport(*ghostedMatrix, *exporter, Tpetra::ADD);
      ownedMatrix->fillComplete();
    }
    return ownedMatrix;
  }
 
  Teuchos::RCP<Tpetra::MultiVector<double,panzer::LocalOrdinal,panzer::GlobalOrdinal,panzer::TpetraNodeType>>
  panzer::L2Projection::buildInverseLumpedMassMatrix()
  {
    PANZER_FUNC_TIME_MONITOR_DIFF("L2Projection<panzer::LocalOrdinal,panzer::GlobalOrdinal>::buildInverseLumpedMassMatrix",buildInvLMM);
    using Teuchos::rcp;
    const auto massMatrix = this->buildMassMatrix(true);
    const auto lumpedMassMatrix = rcp(new Tpetra::MultiVector<double,panzer::LocalOrdinal,panzer::GlobalOrdinal,panzer::TpetraNodeType>(massMatrix->getDomainMap(),1,true));
    const auto tmp = rcp(new Tpetra::MultiVector<double,panzer::LocalOrdinal,panzer::GlobalOrdinal,panzer::TpetraNodeType>(massMatrix->getRangeMap(),1,false));
    tmp->putScalar(1.0);
    {
      PANZER_FUNC_TIME_MONITOR_DIFF("Apply",Apply);
      massMatrix->apply(*tmp,*lumpedMassMatrix);
    }
    {
      PANZER_FUNC_TIME_MONITOR_DIFF("Reciprocal",Reciprocal);
      lumpedMassMatrix->reciprocal(*lumpedMassMatrix);
    }
    return lumpedMassMatrix;
  }
 
  Teuchos::RCP<Tpetra::CrsMatrix<double,panzer::LocalOrdinal,panzer::GlobalOrdinal,panzer::TpetraNodeType>>
  panzer::L2Projection::buildRHSMatrix(const panzer::GlobalIndexer& sourceGlobalIndexer,
                                       const Teuchos::RCP<const Tpetra::Map<panzer::LocalOrdinal,panzer::GlobalOrdinal,panzer::TpetraNodeType>>& inputOwnedSourceMap,
                                       const std::string& sourceFieldName,
                                       const panzer::BasisDescriptor& sourceBasisDescriptor,
                                       const int directionIndex)
  {
    // *******************
    // Create Retangular matrix (both ghosted and owned).
    // *******************
    using Teuchos::RCP;
    using Teuchos::rcp;
    using MapType = Tpetra::Map<panzer::LocalOrdinal,panzer::GlobalOrdinal,panzer::TpetraNodeType>;
    using GraphType = Tpetra::CrsGraph<panzer::LocalOrdinal,panzer::GlobalOrdinal,panzer::TpetraNodeType>;
    using ExportType = Tpetra::Export<panzer::LocalOrdinal,panzer::GlobalOrdinal,panzer::TpetraNodeType>;
    using MatrixType = Tpetra::CrsMatrix<double,panzer::LocalOrdinal,panzer::GlobalOrdinal,panzer::TpetraNodeType>;
 
    // *******************
    // Build ghosted graph
    // *******************
 
    RCP<MapType> ghostedTargetMap;
    {
      std::vector<panzer::GlobalOrdinal> indices;
      targetGlobalIndexer_->getOwnedAndGhostedIndices(indices);
      ghostedTargetMap = rcp(new MapType(Teuchos::OrdinalTraits<panzer::GlobalOrdinal>::invalid(),indices,0,comm_));
    }
 
    RCP<MapType> ghostedSourceMap;
    {
      std::vector<panzer::GlobalOrdinal> indices;
      sourceGlobalIndexer.getOwnedAndGhostedIndices(indices);
      ghostedSourceMap = rcp(new MapType(Teuchos::OrdinalTraits<panzer::GlobalOrdinal>::invalid(),indices,0,comm_));
    }
 
 
    // Now insert the non-zero pattern per row
    // count number of entries per row; required by CrsGraph constructor
    std::vector<size_t> nEntriesPerRow(ghostedTargetMap->getNodeNumElements(),0);
    std::vector<std::string> elementBlockIds;
    targetGlobalIndexer_->getElementBlockIds(elementBlockIds);
    std::vector<std::string>::const_iterator blockItr;
    for (blockItr=elementBlockIds.begin();blockItr!=elementBlockIds.end();++blockItr) {
      std::string blockId = *blockItr;
      const std::vector<panzer::LocalOrdinal> & elements = targetGlobalIndexer_->getElementBlock(blockId);
 
      std::vector<panzer::GlobalOrdinal> row_gids;
      std::vector<panzer::GlobalOrdinal> col_gids;
 
      for(std::size_t elmt=0;elmt<elements.size();elmt++) {
        targetGlobalIndexer_->getElementGIDs(elements[elmt],row_gids);
        sourceGlobalIndexer.getElementGIDs(elements[elmt],col_gids);
        for(std::size_t row=0;row<row_gids.size();row++) {
          panzer::LocalOrdinal lid = 
                               ghostedTargetMap->getLocalElement(row_gids[row]);
          nEntriesPerRow[lid] += col_gids.size();
        }
      }
    }
 
    Teuchos::ArrayView<const size_t> nEntriesPerRowView(nEntriesPerRow);
    RCP<GraphType> ghostedGraph = rcp(new GraphType(ghostedTargetMap,ghostedSourceMap,nEntriesPerRowView,Tpetra::StaticProfile));
 
    for (blockItr=elementBlockIds.begin();blockItr!=elementBlockIds.end();++blockItr) {
      std::string blockId = *blockItr;
      const std::vector<panzer::LocalOrdinal> & elements = targetGlobalIndexer_->getElementBlock(blockId);
 
      std::vector<panzer::GlobalOrdinal> row_gids;
      std::vector<panzer::GlobalOrdinal> col_gids;
 
      for(std::size_t elmt=0;elmt<elements.size();elmt++) {
        targetGlobalIndexer_->getElementGIDs(elements[elmt],row_gids);
        sourceGlobalIndexer.getElementGIDs(elements[elmt],col_gids);
        for(std::size_t row=0;row<row_gids.size();row++)
          ghostedGraph->insertGlobalIndices(row_gids[row],col_gids);
      }
    }
 
    RCP<MapType> ownedTargetMap;
    {
      std::vector<panzer::GlobalOrdinal> indices;
      targetGlobalIndexer_->getOwnedIndices(indices);
      ownedTargetMap = rcp(new MapType(Teuchos::OrdinalTraits<panzer::GlobalOrdinal>::invalid(),indices,0,comm_));
    }
 
    RCP<const MapType> ownedSourceMap = inputOwnedSourceMap;
    if (is_null(ownedSourceMap)) {
      std::vector<panzer::GlobalOrdinal> indices;
      sourceGlobalIndexer.getOwnedIndices(indices);
      ownedSourceMap = rcp(new MapType(Teuchos::OrdinalTraits<panzer::GlobalOrdinal>::invalid(),indices,0,comm_));
    }
 
    // Fill complete with owned range and domain map
    ghostedGraph->fillComplete(ownedSourceMap,ownedTargetMap);
 
    // *****************
    // Build owned graph
    // *****************
 
    RCP<GraphType> ownedGraph = rcp(new GraphType(ownedTargetMap,0));
    RCP<const ExportType> exporter = rcp(new ExportType(ghostedTargetMap,ownedTargetMap));
    ownedGraph->doExport(*ghostedGraph, *exporter, Tpetra::INSERT);
    ownedGraph->fillComplete(ownedSourceMap,ownedTargetMap);
 
    RCP<MatrixType> ghostedMatrix = rcp(new MatrixType(ghostedGraph));
    RCP<MatrixType> ownedMatrix = rcp(new MatrixType(ownedGraph));
    // ghostedMatrix.fillComplete();
    // ghostedMatrix.resumeFill();
 
    ghostedMatrix->setAllToScalar(0.0);
    ownedMatrix->setAllToScalar(0.0);
    PHX::Device().fence();
 
    // *******************
    // Fill ghosted matrix
    // *******************
    for (const auto& block : elementBlockNames_) {
 
      panzer::WorksetDescriptor wd(block,panzer::WorksetSizeType::ALL_ELEMENTS,true,true);
      const auto& worksets = worksetContainer_->getWorksets(wd);
      for (const auto& workset : *worksets) {
 
        // Get target basis values: current implementation assumes target basis is HGrad
        const auto& targetBasisValues = workset.getBasisValues(targetBasisDescriptor_,integrationDescriptor_);
        const auto& targetWeightedBasis = targetBasisValues.weighted_basis_scalar.get_static_view();
 
        // Sources can be any basis
        const auto& sourceBasisValues = workset.getBasisValues(sourceBasisDescriptor,integrationDescriptor_);
        Kokkos::View<const double***,PHX::Device> sourceUnweightedScalarBasis;
        Kokkos::View<const double****,PHX::Device> sourceUnweightedVectorBasis;
        bool useRankThreeBasis = false; // default to gradient or vector basis
        if ( (sourceBasisDescriptor.getType() == "HGrad") || (sourceBasisDescriptor.getType() == "Const") || (sourceBasisDescriptor.getType() == "HVol") ) {
          if (directionIndex == -1) { // Project dof value
            sourceUnweightedScalarBasis = sourceBasisValues.basis_scalar.get_static_view();
            useRankThreeBasis = true;
          }
          else { // Project dof gradient of scalar basis
            sourceUnweightedVectorBasis = sourceBasisValues.grad_basis.get_static_view();
          }
        }
        else { // Project vector value
          sourceUnweightedVectorBasis = sourceBasisValues.basis_vector.get_static_view();
        }
 
        // Get the element local ids
        Kokkos::View<panzer::LocalOrdinal**,PHX::Device> targetLocalIds("buildRHSMatrix: targetLocalIds", workset.numOwnedCells(),
                                                      targetGlobalIndexer_->getElementBlockGIDCount(block));
        Kokkos::View<panzer::LocalOrdinal**,PHX::Device> sourceLocalIds("buildRHSMatrix: sourceLocalIds", workset.numOwnedCells(),
                                                      sourceGlobalIndexer.getElementBlockGIDCount(block));
        {
          // Remove the ghosted cell ids or the call to getElementLocalIds will spill array bounds
          const auto cellLocalIdsNoGhost = Kokkos::subview(workset.cell_local_ids_k,std::make_pair(0,workset.numOwnedCells()));
          targetGlobalIndexer_->getElementLIDs(cellLocalIdsNoGhost,targetLocalIds);
          sourceGlobalIndexer.getElementLIDs(cellLocalIdsNoGhost,sourceLocalIds);
        }
 
        // Get the offsets
        Kokkos::View<panzer::LocalOrdinal*,PHX::Device> targetFieldOffsets;
        {
          const auto fieldIndex = targetGlobalIndexer_->getFieldNum(targetBasisDescriptor_.getType());
          const std::vector<panzer::LocalOrdinal>& offsets = targetGlobalIndexer_->getGIDFieldOffsets(block,fieldIndex);
          targetFieldOffsets = Kokkos::View<panzer::LocalOrdinal*,PHX::Device>("L2Projection:buildRHS:targetFieldOffsets",offsets.size());
          const auto hostOffsets = Kokkos::create_mirror_view(targetFieldOffsets);
          for(size_t i=0; i < offsets.size(); ++i)
            hostOffsets(i) = offsets[i];
          Kokkos::deep_copy(targetFieldOffsets,hostOffsets);
          PHX::Device().fence();
        }
 
        Kokkos::View<panzer::LocalOrdinal*,PHX::Device> sourceFieldOffsets;
        {
          const auto fieldIndex = sourceGlobalIndexer.getFieldNum(sourceFieldName);
          const std::vector<panzer::LocalOrdinal>& offsets = sourceGlobalIndexer.getGIDFieldOffsets(block,fieldIndex);
          TEUCHOS_TEST_FOR_EXCEPTION(offsets.size() == 0, std::runtime_error,
                                     "ERROR: panzer::L2Projection::buildRHSMatrix() - The source field, \""
                                     << sourceFieldName << "\", does not exist in element block \""
                                     << block << "\"!");
          sourceFieldOffsets = Kokkos::View<panzer::LocalOrdinal*,PHX::Device>("L2Projection:buildRHS:sourceFieldOffsets",offsets.size());
          const auto hostOffsets = Kokkos::create_mirror_view(sourceFieldOffsets);
          for(size_t i=0; i <offsets.size(); ++i)
            hostOffsets(i) = offsets[i];
          Kokkos::deep_copy(sourceFieldOffsets,hostOffsets);
          PHX::Device().fence();
        }
 
        const auto localMatrix = ghostedMatrix->getLocalMatrix();
        const int numRows = static_cast<int>(targetWeightedBasis.extent(1));
        int tmpNumCols = -1;
        int tmpNumQP = -1;
        if (useRankThreeBasis) {
          tmpNumCols = static_cast<int>(sourceUnweightedScalarBasis.extent(1));
          tmpNumQP = static_cast<int>(sourceUnweightedScalarBasis.extent(2));
        }
        else {
          tmpNumCols = static_cast<int>(sourceUnweightedVectorBasis.extent(1));
          tmpNumQP = static_cast<int>(sourceUnweightedVectorBasis.extent(2));
        }
        const int numCols = tmpNumCols;
        const int numQP = tmpNumQP;
 
        Kokkos::parallel_for(Kokkos::RangePolicy<PHX::Device>(0,workset.numOwnedCells()),KOKKOS_LAMBDA (const int& cell) {
          panzer::LocalOrdinal cLIDs[256];
          double vals[256];
          for (int row = 0; row < numRows; ++row) {
            const int rowOffset = targetFieldOffsets(row);
            const int rowLID = targetLocalIds(cell,rowOffset);
            for (int col = 0; col < numCols; ++col)
              vals[col] = 0.0;
 
            for (int col = 0; col < numCols; ++col) {
              for (int qp = 0; qp < numQP; ++qp) {
                const int colOffset = sourceFieldOffsets(col);
                const int colLID = sourceLocalIds(cell,colOffset);
                cLIDs[col] = colLID;
                if (useRankThreeBasis)
                  vals[col] += sourceUnweightedScalarBasis(cell,col,qp) * targetWeightedBasis(cell,row,qp);
                else
                  vals[col] += sourceUnweightedVectorBasis(cell,col,qp,directionIndex) * targetWeightedBasis(cell,row,qp);
              }
            }
            localMatrix.sumIntoValues(rowLID,cLIDs,numCols,vals,true,true);
          }
        });
      }
 
    }
    ghostedMatrix->fillComplete(ownedSourceMap,ownedTargetMap);
    ownedMatrix->resumeFill();
    ownedMatrix->doExport(*ghostedMatrix,*exporter,Tpetra::ADD);
    ownedMatrix->fillComplete(ownedSourceMap,ownedTargetMap);
 
    return ownedMatrix;
  }
 
}
 
#endif