Ifpack_ILU: A class for constructing and using an incomplete lower/upper (ILU) factorization of a given Epetra_RowMatrix. More...

#include <Ifpack_ILU.h>

Inheritance diagram for Ifpack_ILU:

[legend]

Collaboration diagram for Ifpack_ILU:

[legend]

Public Member Functions

	Ifpack_ILU (Epetra_RowMatrix *A)
	Constructor.

	~Ifpack_ILU ()
	Destructor.


int	Initialize ()
	Initialize the preconditioner, does not touch matrix values.

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

int	Compute ()
	Compute ILU factors L and 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	SetParameters (Teuchos::ParameterList &parameterlist)
	Set parameters using a Teuchos::ParameterList object.

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


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

int	Multiply (bool Trans, const Epetra_MultiVector &X, Epetra_MultiVector &Y) const

int	ApplyInverse (const Epetra_MultiVector &X, Epetra_MultiVector &Y) const
	Returns the result of a Epetra_Operator inverse applied to an Epetra_MultiVector X in Y. More...

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

double	Condest () const
	Returns the computed estimated condition number, or -1.0 if not computed.


const Epetra_CrsMatrix &	L () const
	Returns the address of the L factor associated with this factored matrix.

const Epetra_Vector &	D () const
	Returns the address of the D factor associated with this factored matrix.

const Epetra_CrsMatrix &	U () const
	Returns the address of the L factor associated with this factored matrix.

const char *	Label () const
	Returns a character string describing the operator.

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

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.

virtual std::ostream &	Print (std::ostream &os) const
	Prints on stream basic information about `this` object.

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.

Detailed Description

Ifpack_ILU: A class for constructing and using an incomplete lower/upper (ILU) factorization of a given Epetra_RowMatrix.

The Ifpack_ILU class computes a "relaxed" ILU factorization with level k fill of a given Epetra_RowMatrix. The notion of relaxation is the same as described in "Experimental study of ILU preconditioners for indefinite matrices" by Chow and Saad.

Please refer to General description of incomplete factorizations for a general description of the ILU algorithm.

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

Author: Mike Heroux, Marzio Sala, SNL 9214.

Date: Last modified on 22-Jan-05.

Definition at line 89 of file Ifpack_ILU.h.

Member Function Documentation

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

virtual

Returns the result of a Epetra_Operator inverse applied to an Epetra_MultiVector X in Y.

In this implementation, we use several existing attributes to determine how virtual method ApplyInverse() should call the concrete method Solve(). We pass in the UpperTriangular(), the Epetra_CrsMatrix::UseTranspose(), and NoDiagonal() methods. The most notable warning is that if a matrix has no diagonal values we assume that there is an implicit unit diagonal that should be accounted for when doing a triangular solve.

Parameters

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

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

Implements Ifpack_Preconditioner.

Definition at line 575 of file Ifpack_ILU.cpp.

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

int Ifpack_ILU::Compute ( )

virtual

Compute ILU factors L and U using the specified graph, diagonal perturbation thresholds and relaxation parameters.

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

Ifpack_IlukGraph specifying the structure of L and U.
Value for the ILU(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 334 of file Ifpack_ILU.cpp.

References Comm(), Epetra_Time::ElapsedTime(), Initialize(), IsInitialized(), and Epetra_Time::ResetStartTime().

int Ifpack_ILU::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 150 of file Ifpack_ILU.h.

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

Public Member Functions

Detailed Description

Member Function Documentation