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MueLu_NullspacePresmoothFactory_def.hpp
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46 #ifndef MUELU_NULLSPACEPRESMOOTHFACTORY_DEF_HPP
47 #define MUELU_NULLSPACEPRESMOOTHFACTORY_DEF_HPP
48 
49 #include <Xpetra_Matrix.hpp>
50 #include <Xpetra_MultiVector.hpp>
52 
54 #include "MueLu_Utilities.hpp"
55 
56 #include "MueLu_Monitor.hpp"
57 
58 namespace MueLu {
59 
60  template <class Scalar, class LocalOrdinal, class GlobalOrdinal, class Node>
62  RCP<ParameterList> validParamList = rcp(new ParameterList());
63 
64  validParamList->set< RCP<const FactoryBase> >("A" , Teuchos::null, "Generating factory for A");
65  validParamList->set< RCP<const FactoryBase> >("Nullspace", Teuchos::null, "Generating factory for the nonsmoothed nullspace");
66 
67  return validParamList;
68  }
69 
70  template <class Scalar,class LocalOrdinal, class GlobalOrdinal, class Node>
72  Input(currentLevel, "Nullspace");
73 
74  if (currentLevel.GetLevelID() == 0)
75  Input(currentLevel, "A");
76  }
77 
78  template <class Scalar,class LocalOrdinal, class GlobalOrdinal, class Node>
80  FactoryMonitor m(*this, "Nullspace presmooth factory", currentLevel);
81 
82  RCP<MultiVector> newB;
83  if (currentLevel.GetLevelID() == 0) {
84  RCP<Matrix> A = Get< RCP<Matrix> > (currentLevel, "A");
85  RCP<MultiVector> B = Get< RCP<MultiVector> >(currentLevel, "Nullspace");
86  newB = MultiVectorFactory::Build(B->getMap(), B->getNumVectors());
87 
89 
90  SC damping = 4./3;
91  damping /= Utilities::PowerMethod(*A, true, (LO) 10, 1e-4);
92 
93  A->apply(*B, *newB, Teuchos::NO_TRANS);
94 
95  size_t numVec = newB->getNumVectors();
96  LO numElements = newB->getLocalLength();
97  for (size_t j = 0; j < numVec; j++) {
98  Teuchos::ArrayRCP<const SC> Bj = B->getData(j);
99  Teuchos::ArrayRCP<SC> newBj = newB->getDataNonConst(j);
100 
101  for (LO i = 0; i < numElements; i++)
102  newBj[i] = Bj[i] - damping*newBj[i]/D[i];
103  }
104  } else {
105  newB = Get< RCP<MultiVector> >(currentLevel, "Nullspace");
106  }
107 
108  // provide "Nullspace" variable on current level
109  Set(currentLevel, "Nullspace", newB);
110 
111  } // Build
112 
113 } //namespace MueLu
114 
115 #endif // MUELU_NULLSPACEPRESMOOTHFACTORY_DEF_HPP
static Teuchos::ArrayRCP< Scalar > GetMatrixDiagonal(const Xpetra::Matrix< Scalar, LocalOrdinal, GlobalOrdinal, Node > &A)
void Build(Level &currentLevel) const
Build an object with this factory.
ParameterList & set(std::string const &name, T const &value, std::string const &docString="", RCP< const ParameterEntryValidator > const &validator=null)
Timer to be used in factories. Similar to Monitor but with additional timers.
RCP< const ParameterList > GetValidParameterList() const
Return a const parameter list of valid parameters that setParameterList() will accept.
LocalOrdinal LO
TEUCHOS_DEPRECATED RCP< T > rcp(T *p, Dealloc_T dealloc, bool owns_mem)
Class that holds all level-specific information.
Definition: MueLu_Level.hpp:99
Scalar SC
void DeclareInput(Level &currentLevel) const
Specifies the data that this class needs, and the factories that generate that data.
int GetLevelID() const
Return level number.
Definition: MueLu_Level.cpp:76
static Scalar PowerMethod(const Xpetra::Matrix< Scalar, LocalOrdinal, GlobalOrdinal, Node > &A, bool scaleByDiag=true, LocalOrdinal niters=10, Magnitude tolerance=1e-2, bool verbose=false, unsigned int seed=123)