void EpetraLinearOp::computeAbsRowSum(Epetra_Vector & x) const
{
TEUCHOS_ASSERT(!is_null(rowMatrix_));
RCP<Epetra_CrsMatrix> crsMatrix
= Teuchos::rcp_dynamic_cast<Epetra_CrsMatrix>(rowMatrix_);
TEUCHOS_TEST_FOR_EXCEPTION(is_null(crsMatrix),
Exceptions::OpNotSupported,
"EpetraLinearOp::computeAbsRowSum(...): wrapped matrix must be of type "
"Epetra_CrsMatrix for this method. Other operator types are not supported."
);
//
// Put inverse of the sum of absolute values of the ith row of A in x[i].
// (this is a modified copy of Epetra_CrsMatrix::InvRowSums)
//
if (crsMatrix->Filled()) {
TEUCHOS_TEST_FOR_EXCEPTION(is_null(crsMatrix),
std::invalid_argument,
"EpetraLinearOp::computeAbsRowSum(...): Epetra_CrsMatrix must be filled"
);
}
int i, j;
x.PutScalar(0.0); // Make sure we sum into a vector of zeros.
double * xp = (double*)x.Values();
if (crsMatrix->Graph().RangeMap().SameAs(x.Map()) && crsMatrix->Exporter() != 0) {
Epetra_Vector x_tmp(crsMatrix->RowMap());
x_tmp.PutScalar(0.0);
double * x_tmp_p = (double*)x_tmp.Values();
for (i=0; i < crsMatrix->NumMyRows(); i++) {
int NumEntries = 0;
double * RowValues = 0;
crsMatrix->ExtractMyRowView(i,NumEntries,RowValues);
for (j=0; j < NumEntries; j++) x_tmp_p[i] += std::abs(RowValues[j]);
}
TEUCHOS_TEST_FOR_EXCEPT(0!=x.Export(x_tmp, *crsMatrix->Exporter(), Add)); //Export partial row sums to x.
}
else if (crsMatrix->Graph().RowMap().SameAs(x.Map())) {
for (i=0; i < crsMatrix->NumMyRows(); i++) {
int NumEntries = 0;
double * RowValues = 0;
crsMatrix->ExtractMyRowView(i,NumEntries,RowValues);
double scale = 0.0;
for (j=0; j < NumEntries; j++) scale += std::abs(RowValues[j]);
xp[i] = scale;
}
}
else { // x.Map different than both crsMatrix->Graph().RowMap() and crsMatrix->Graph().RangeMap()
TEUCHOS_TEST_FOR_EXCEPT(true); // The map of x must be the RowMap or RangeMap of A.
}
}
