Ifpack_ILUT: A class for constructing and using an incomplete LU factorization of a given Epetra_RowMatrix. More...

#include <Ifpack_ILUT.h>

Inheritance diagram for Ifpack_ILUT:

Collaboration diagram for Ifpack_ILUT:

Public Member Functions

	Ifpack_ILUT (const Epetra_RowMatrix *A)
	Ifpack_ILUT constuctor with variable number of indices per row.

virtual	~Ifpack_ILUT ()
	Ifpack_ILUT Destructor.


int	SetParameters (Teuchos::ParameterList &parameterlis)
	Set parameters using a Teuchos::ParameterList object.

int	Initialize ()
	Initialize L and U with values from user matrix A. More...

bool	IsInitialized () const
	Returns `true` if the preconditioner has been successfully initialized.

int	Compute ()
	Compute IC factor U using the specified graph, diagonal perturbation thresholds and relaxation parameters. More...

bool	IsComputed () const
	If factor is completed, this query returns true, otherwise it returns false.

int	ApplyInverse (const Epetra_MultiVector &X, Epetra_MultiVector &Y) const
	Returns the result of a Ifpack_ILUT forward/back solve on a Epetra_MultiVector X in Y. More...

int	Apply (const Epetra_MultiVector &X, Epetra_MultiVector &Y) const

double	Condest (const Ifpack_CondestType CT=Ifpack_Cheap, const int MaxIters=1550, const double Tol=1e-9, Epetra_RowMatrix *Matrix_in=0)
	Computed the estimated condition number and returns the value.

double	Condest () const
	Returns the computed estimated condition number, or -1.0 if no computed.

int	SetUseTranspose (bool UseTranspose_in)
	If set true, transpose of this operator will be applied. More...

double	NormInf () const
	Returns 0.0 because this class cannot compute Inf-norm.

bool	HasNormInf () const
	Returns false because this class cannot compute an Inf-norm.

bool	UseTranspose () const
	Returns the current UseTranspose setting.

const Epetra_Map &	OperatorDomainMap () const
	Returns the Epetra_Map object associated with the domain of this operator.

const Epetra_Map &	OperatorRangeMap () const
	Returns the Epetra_Map object associated with the range of this operator.

const Epetra_Comm &	Comm () const
	Returns the Epetra_BlockMap object associated with the range of this matrix operator.

const Epetra_RowMatrix &	Matrix () const
	Returns a reference to the matrix to be preconditioned.

const Epetra_CrsMatrix &	L () const
	Returns a reference to the L factor.

const Epetra_CrsMatrix &	U () const
	Returns a reference to the U factor.

const char *	Label () const
	Returns the label of `this` object.

int	SetLabel (const char *Label_in)
	Sets the label for `this` object.

virtual std::ostream &	Print (std::ostream &os) const
	Prints basic information on iostream. This function is used by operator<<.

virtual int	NumInitialize () const
	Returns the number of calls to Initialize().

virtual int	NumCompute () const
	Returns the number of calls to Compute().

virtual int	NumApplyInverse () const
	Returns the number of calls to ApplyInverse().

virtual double	InitializeTime () const
	Returns the time spent in Initialize().

virtual double	ComputeTime () const
	Returns the time spent in Compute().

virtual double	ApplyInverseTime () const
	Returns the time spent in ApplyInverse().

virtual double	InitializeFlops () const
	Returns the number of flops in the initialization phase.

virtual double	ComputeFlops () const
	Returns the number of flops in the computation phase.

virtual double	ApplyInverseFlops () const
	Returns the number of flops in the application of the preconditioner.

double	LevelOfFill () const

double	RelaxValue () const
	Set relative threshold value.

double	AbsoluteThreshold () const
	Get absolute threshold value.

double	RelativeThreshold () const
	Get relative threshold value.

double	DropTolerance () const
	Gets the dropping tolerance.

int	NumGlobalNonzeros () const
	Returns the number of nonzero entries in the global graph.

long long	NumGlobalNonzeros64 () const

int	NumMyNonzeros () const
	Returns the number of nonzero entries in the local graph.

Detailed Description

Ifpack_ILUT: A class for constructing and using an incomplete LU factorization of a given Epetra_RowMatrix.

The Ifpack_ILUT class computes a "Relaxed" ILUT factorization with dual threshold dropping of small elements of a given Epetra_RowMatrix.

This implementation does not use the algorithm that is described in General description of incomplete factorizations. The algorithm drops entries in a row (i) of matrix A that are smaller than drop_tolerance even before the factorization of row i then computes the factorization for that row. This is different than the usual algorithm where the drop tolerance is applied to the factored rows.

The complete list of supported parameters is reported in page List of Supported Parameters.

Author: Marzio Sala, SNL 9214.

Date: Last modified on 22-Jan-05.

Definition at line 81 of file Ifpack_ILUT.h.

Member Function Documentation

int Ifpack_ILUT::ApplyInverse	(	const Epetra_MultiVector &	X,
		Epetra_MultiVector &	Y
	)		const

virtual

Returns the result of a Ifpack_ILUT forward/back solve on a Epetra_MultiVector X in Y.

Parameters

X	- (In) A Epetra_MultiVector of dimension NumVectors to solve for.
Y	- (Out) A Epetra_MultiVector of dimension NumVectorscontaining result.

Returns: Integer error code, set to 0 if successful.

Implements Ifpack_Preconditioner.

Definition at line 537 of file Ifpack_ILUT.cpp.

References Epetra_Time::ElapsedTime(), IsComputed(), and Epetra_Time::ResetStartTime().

int Ifpack_ILUT::Compute ( )

virtual

Compute IC factor U using the specified graph, diagonal perturbation thresholds and relaxation parameters.

This function computes the RILU(k) factors L and U using the current:

Ifpack_IlukGraph specifying the structure of L and U.
Value for the RILU(k) relaxation parameter.
Value for the a priori diagonal threshold values.

InitValues() must be called before the factorization can proceed.

Implements Ifpack_Preconditioner.

Definition at line 495 of file Ifpack_ILUT.cpp.

References Comm(), Initialize(), IsInitialized(), Epetra_RowMatrix::NumMyRows(), Epetra_Comm::NumProc(), Epetra_Time::ResetStartTime(), and Epetra_RowMatrix::RowMatrixRowMap().

int Ifpack_ILUT::Initialize ( )

virtual

Initialize L and U with values from user matrix A.

Copies values from the user's matrix into the nonzero pattern of L and U.

Parameters

In	A - User matrix to be factored.

Warning: The graph of A must be identical to the graph passed in to Ifpack_IlukGraph constructor.

Implements Ifpack_Preconditioner.

Definition at line 144 of file Ifpack_ILUT.cpp.

References Comm(), Epetra_Time::ElapsedTime(), Matrix(), Epetra_RowMatrix::NumMyRows(), and Epetra_Time::ResetStartTime().

Referenced by Compute().

int Ifpack_ILUT::SetUseTranspose ( bool UseTranspose_in )

inlinevirtual

If set true, transpose of this operator will be applied.

This flag allows the transpose of the given operator to be used implicitly. Setting this flag affects only the Apply() and ApplyInverse() methods. If the implementation of this interface does not support transpose use, this method should return a value of -1.

Parameters

UseTranspose_in - (In) If true, multiply by the transpose of operator, otherwise just use operator.

Returns: Always returns 0.

Implements Epetra_Operator.

Definition at line 168 of file Ifpack_ILUT.h.

The documentation for this class was generated from the following files:

Public Member Functions

Detailed Description

Member Function Documentation