IFPACK Development
Ifpack_DiagonalFilter.cpp
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00004 //       Ifpack: Object-Oriented Algebraic Preconditioner Package
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00042 
00043 #include "Ifpack_ConfigDefs.h"
00044 #include "Ifpack_DiagonalFilter.h"
00045 #include "Epetra_ConfigDefs.h"
00046 #include "Epetra_RowMatrix.h"
00047 #include "Epetra_Comm.h"
00048 #include "Epetra_Map.h"
00049 #include "Epetra_MultiVector.h"
00050 #include "Epetra_Vector.h"
00051 
00052 //==============================================================================
00053 Ifpack_DiagonalFilter::Ifpack_DiagonalFilter(const Teuchos::RefCountPtr<Epetra_RowMatrix>& Matrix,
00054                          double AbsoluteThreshold,
00055                          double RelativeThreshold) :
00056   A_(Matrix),
00057   AbsoluteThreshold_(AbsoluteThreshold),
00058   RelativeThreshold_(RelativeThreshold)
00059 {
00060   Epetra_Time Time(Comm());
00061   
00062   pos_.resize(NumMyRows());
00063   val_.resize(NumMyRows());
00064   
00065   std::vector<int> Indices(MaxNumEntries());
00066   std::vector<double> Values(MaxNumEntries());
00067   int NumEntries;
00068   
00069   for (int MyRow = 0 ; MyRow < NumMyRows() ; ++MyRow) {
00070     
00071     pos_[MyRow] = -1;
00072     val_[MyRow] = 0.0;
00073     int ierr = A_->ExtractMyRowCopy(MyRow, MaxNumEntries(), NumEntries,
00074                     &Values[0], &Indices[0]);
00075     assert (ierr == 0);
00076     
00077     for (int i = 0 ; i < NumEntries ; ++i) {
00078       if (Indices[i] == MyRow) {
00079     pos_[MyRow] = i;
00080     val_[MyRow] = Values[i] * (RelativeThreshold_ - 1) +
00081       AbsoluteThreshold_ * EPETRA_SGN(Values[i]);
00082       }
00083       break;
00084     }
00085   }
00086   cout << "TIME = " << Time.ElapsedTime() << endl;
00087 }
00088 
00089 //==============================================================================
00090 int Ifpack_DiagonalFilter::
00091 ExtractMyRowCopy(int MyRow, int Length, int& NumEntries, 
00092          double* Values, int* Indices) const
00093 {
00094 
00095   IFPACK_CHK_ERR(A_->ExtractMyRowCopy(MyRow, Length, NumEntries,
00096                      Values,Indices));
00097 
00098   if (pos_[MyRow] != -1)
00099     Values[pos_[MyRow]] += val_[MyRow];
00100 
00101   return(0);
00102 }
00103 
00104 //==============================================================================
00105 int Ifpack_DiagonalFilter::
00106 Multiply(bool TransA, const Epetra_MultiVector& X, 
00107      Epetra_MultiVector& Y) const
00108 {
00109 
00110   if (X.NumVectors() != Y.NumVectors())
00111     IFPACK_CHK_ERR(-2);
00112 
00113   IFPACK_CHK_ERR(A_->Multiply(TransA, X, Y));
00114 
00115   for (int v = 0 ; v < X.NumVectors() ; ++v)
00116     for (int i = 0 ; i < NumMyRows() ; ++i)
00117       Y[v][i] += val_[i] * X[v][i];
00118       
00119 
00120   return(0);
00121 }
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