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MueLu_ThresholdAFilterFactory_def.hpp
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46 #ifndef MUELU_THRESHOLDAFILTERFACTORY_DEF_HPP
47 #define MUELU_THRESHOLDAFILTERFACTORY_DEF_HPP
48 
49 #include <Xpetra_Matrix.hpp>
50 #include <Xpetra_CrsMatrixWrap.hpp>
51 
53 
54 #include "MueLu_Level.hpp"
55 #include "MueLu_Monitor.hpp"
56 
57 namespace MueLu {
58 
59  template <class Scalar, class LocalOrdinal, class GlobalOrdinal, class Node>
60  ThresholdAFilterFactory<Scalar, LocalOrdinal, GlobalOrdinal, Node>::ThresholdAFilterFactory(const std::string& ename, const Scalar threshold, const bool keepDiagonal, const GlobalOrdinal expectedNNZperRow)
61  : varName_(ename), threshold_(threshold), keepDiagonal_(keepDiagonal), expectedNNZperRow_(expectedNNZperRow)
62  { }
63 
64  template <class Scalar, class LocalOrdinal, class GlobalOrdinal, class Node>
66 
67  template <class Scalar, class LocalOrdinal, class GlobalOrdinal, class Node>
69  Input(currentLevel, varName_);
70  }
71 
72  template <class Scalar, class LocalOrdinal, class GlobalOrdinal, class Node>
74  Build (Level & currentLevel) const
75  {
76  FactoryMonitor m (*this, "A filter (thresholding)", currentLevel);
77 
78  typedef Xpetra::Matrix<Scalar, LocalOrdinal, GlobalOrdinal, Node> OMatrix; //TODO
79  typedef Xpetra::CrsMatrixWrap<Scalar, LocalOrdinal, GlobalOrdinal, Node> CrsOMatrix; //TODO
80 
81  RCP<OMatrix> Ain = Get< RCP<OMatrix> >(currentLevel, varName_);
82 
83  // create new empty Matrix
84  RCP<const Map> rowmap = Ain->getRowMap();
85  RCP<const Map> colmap = Ain->getColMap();
86  RCP<CrsOMatrix> Aout = rcp(new CrsOMatrix(rowmap, expectedNNZperRow_ <= 0 ? Ain->getGlobalMaxNumRowEntries() : expectedNNZperRow_ , Xpetra::DynamicProfile));
87  // loop over local rows
88  for(size_t row=0; row<Ain->getNodeNumRows(); row++)
89  {
90  size_t nnz = Ain->getNumEntriesInLocalRow(row);
91 
92  Teuchos::ArrayView<const LocalOrdinal> indices;
93  Teuchos::ArrayView<const Scalar> vals;
94  Ain->getLocalRowView(row, indices, vals);
95 
96  TEUCHOS_TEST_FOR_EXCEPTION(Teuchos::as<size_t>(indices.size()) != nnz, Exceptions::RuntimeError, "MueLu::ThresholdAFilterFactory::Build: number of nonzeros not equal to number of indices? Error.");
97 
98  Teuchos::ArrayRCP<GlobalOrdinal> indout(indices.size(),Teuchos::ScalarTraits<GlobalOrdinal>::zero());
99  Teuchos::ArrayRCP<Scalar> valout(indices.size(),Teuchos::ScalarTraits<Scalar>::zero());
100  size_t nNonzeros = 0;
101  if (keepDiagonal_) {
102  GlobalOrdinal glbRow = rowmap->getGlobalElement(row);
103  LocalOrdinal lclColIdx = colmap->getLocalElement(glbRow);
104  for(size_t i=0; i<(size_t)indices.size(); i++) {
105  if(Teuchos::ScalarTraits<Scalar>::magnitude(vals[i]) > Teuchos::ScalarTraits<Scalar>::magnitude(threshold_) || indices[i]==lclColIdx) {
106  indout[nNonzeros] = colmap->getGlobalElement(indices[i]); // LID -> GID (column)
107  valout[nNonzeros] = vals[i];
108  nNonzeros++;
109  }
110  }
111  } else
112  for(size_t i=0; i<(size_t)indices.size(); i++) {
113  if(Teuchos::ScalarTraits<Scalar>::magnitude(vals[i]) > Teuchos::ScalarTraits<Scalar>::magnitude(threshold_)) {
114  indout[nNonzeros] = colmap->getGlobalElement(indices[i]); // LID -> GID (column)
115  valout[nNonzeros] = vals[i];
116  nNonzeros++;
117  }
118  }
119 
120  indout.resize(nNonzeros);
121  valout.resize(nNonzeros);
122 
123  Aout->insertGlobalValues(Ain->getRowMap()->getGlobalElement(row), indout.view(0,indout.size()), valout.view(0,valout.size()));
124  }
125 
126  Aout->fillComplete(Ain->getDomainMap(), Ain->getRangeMap());
127 
128  GetOStream(Statistics0) << "Nonzeros in " << varName_ << "(input): " << Ain->getGlobalNumEntries() << ", Nonzeros after filtering " << varName_ << " (parameter: " << threshold_ << "): " << Aout->getGlobalNumEntries() << std::endl;
129 
130  currentLevel.Set(varName_, Teuchos::rcp_dynamic_cast<OMatrix>(Aout), this);
131  }
132 
133 } // namespace MueLu
134 
135 #endif // MUELU_THRESHOLDAFILTERFACTORY_DEF_HPP
Timer to be used in factories. Similar to Monitor but with additional timers.
Namespace for MueLu classes and methods.
Print statistics that do not involve significant additional computation.
ThresholdAFilterFactory(const std::string &ename, const Scalar threshold, const bool keepDiagonal=true, const GlobalOrdinal expectedNNZperRow=-1)
Constructor.
void Build(Level &currentLevel) const
Build an object with this factory.
Class that holds all level-specific information.
Definition: MueLu_Level.hpp:99
void DeclareInput(Level &currentLevel) const
Input.
Exception throws to report errors in the internal logical of the program.