// ============================================================================
bool ML_Epetra::MatrixFreePreconditioner::
CheckSPD(const Epetra_Operator& A, const bool UseApply,
const int NumChecks,
const int NumVectors) const
{
bool res = true;
std::vector<double> norm(NumVectors);
if (!IsComputed())
return(false);
if (MyPID() == 0)
std::cout << "Checking SPD property of the operator... " << std::endl;
Epetra_MultiVector X(A.OperatorDomainMap(), NumVectors);
Epetra_MultiVector AX(A.OperatorRangeMap(), NumVectors);
try
{
for (int i = 0; i < NumChecks; ++i)
{
int ierr;
if (X.Random()) res = false;
if (UseApply)
ierr = A.Apply(X, AX);
else
ierr = A.ApplyInverse(X, AX);
if (ierr < 0)
throw(-1);
AX.Dot(X, &norm[0]);
for (int v = 0; v < NumVectors; ++v)
{
std::cout << norm[v] << std::endl;
if (norm[v] <= 0.0)
throw(-2);
}
}
}
catch(...)
{
res = false;
}
if (MyPID() == 0)
{
if (res)
std::cout << "Passed: all x * A * x are positive." << std::endl;
else
std::cout << "Failed: some x * A * x are negative or zero!" << std::endl;
}
return(res);
}
Teuchos::RCP<Epetra_CrsMatrix> Epetra_Operator_to_Epetra_Matrix::constructInverseMatrix(const Epetra_Operator &op, const Epetra_Map &map)
{
int numEntriesPerRow = 0;
Teuchos::RCP<Epetra_FECrsMatrix> matrix = Teuchos::rcp(new Epetra_FECrsMatrix(::Copy, map, numEntriesPerRow));
int numRows = map.NumGlobalElements();
Epetra_Vector X(map);
Epetra_Vector Y(map);
double tol = 1e-15; // values below this will be considered 0
for (int rowIndex=0; rowIndex<numRows; rowIndex++)
{
int lid = map.LID(rowIndex);
if (lid != -1)
{
X[lid] = 1.0;
}
op.ApplyInverse(X, Y);
if (lid != -1)
{
X[lid] = 0.0;
}
std::vector<double> values;
std::vector<int> indices;
for (int i=0; i<map.NumMyElements(); i++)
{
if (abs(Y[i]) > tol)
{
values.push_back(Y[i]);
indices.push_back(map.GID(i));
}
}
matrix->InsertGlobalValues(rowIndex, values.size(), &values[0], &indices[0]);
}
matrix->GlobalAssemble();
return matrix;
}
