Ifpack_IC Class Reference

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

#include <Ifpack_IC.h>

Inheritance diagram for Ifpack_IC:

[legend]Collaboration diagram for Ifpack_IC:

[legend]List of all members.

Public Member Functions
	Ifpack_IC (Epetra_RowMatrix *A)
	Ifpack_IC constuctor with variable number of indices per row.
virtual	~Ifpack_IC ()
	Ifpack_IC Destructor.
void	SetAbsoluteThreshold (double Athresh)
	Set absolute threshold value.
void	SetRelativeThreshold (double Rthresh)
	Set relative threshold value.
int	SetParameters (Teuchos::ParameterList &parameterlis)
	Set parameters using a Teuchos::ParameterList object.
int	SetParameter (const string Name, const int Value)
int	SetParameter (const string Name, const double Value)
const Epetra_RowMatrix &	Matrix () const
	Returns a pointer to the matrix to be preconditioned.
Epetra_RowMatrix &	Matrix ()
bool	IsInitialized () const
	Returns true if the preconditioner has been successfully initialized, false otherwise.
int	Initialize ()
	Initialize L and U with values from user matrix A.
int	Compute ()
	Compute IC factor U using the specified graph, diagonal perturbation thresholds and relaxation parameters.
int	ComputeSetup ()
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_IC forward/back solve on a Epetra_MultiVector X in Y.
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)
	Returns the maximum over all the condition number estimate for each local ILU set of factors.
double	Condest () const
	Returns the computed condition number estimate, or -1.0 if not computed.
double	GetAbsoluteThreshold ()
	Get absolute threshold value.
double	GetRelativeThreshold ()
	Get relative threshold value.
int	NumGlobalNonzeros () const
	Returns the number of nonzero entries in the global graph.
int	NumMyNonzeros () const
	Returns the number of nonzero entries in the local graph.
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 U factor associated with this factored matrix.
const char *	Label () const
int	SetLabel (const char *Label_in)
virtual 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.
Additional methods required to support the Epetra_Operator interface.
int	SetUseTranspose (bool UseTranspose_in)
	If set true, transpose of this operator will be applied.
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.

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Detailed Description

Ifpack_IC: A class for constructing and using an incomplete Cholesky factorization of a given Epetra_RowMatrix.

The Ifpack_IC class computes a threshold based incomplete LDL^T factorization of a given Epetra_RowMatrix. The factorization that is produced is a function of several parameters:

1. Maximum number of entries per row/column in factor - The factorization will contain at most this number of nonzero terms in each row/column of the factorization.

2. Diagonal perturbation - Prior to computing the factorization, it is possible to modify the diagonal entries of the matrix for which the factorization will be computing. If the absolute and relative perturbation values are zero and one, respectively, the factorization will be compute for the original user matrix A. Otherwise, the factorization will computed for a matrix that differs from the original user matrix in the diagonal values only. Details can be found in ifp_diag_pert.

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Constructor & Destructor Documentation

Ifpack_IC::Ifpack_IC (  Epetra_RowMatrix *  A  )

Ifpack_IC constuctor with variable number of indices per row. Creates a Ifpack_IC object and allocates storage. Parameters: In  A - User matrix to be factored. In  Graph - Graph generated by Ifpack_IlukGraph.

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Member Function Documentation

int Ifpack_IC::ApplyInverse (  const Epetra_MultiVector &  X, Epetra_MultiVector &  Y )  const [virtual]

Returns the result of a Ifpack_IC forward/back solve on a Epetra_MultiVector X in Y. Parameters: In  Trans -If true, solve transpose problem. In  X - A Epetra_MultiVector of dimension NumVectors to solve for. Out  Y -A Epetra_MultiVector of dimension NumVectorscontaining result. Returns: Integer error code, set to 0 if successful. Implements Ifpack_Preconditioner.

int Ifpack_IC::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.

double Ifpack_IC::Condest (  const Ifpack_CondestType  CT = Ifpack_Cheap, const int  MaxIters = 1550, const double  Tol = 1e-9, Epetra_RowMatrix *  Matrix_in = 0 )  [virtual]

Returns the maximum over all the condition number estimate for each local ILU set of factors. This functions computes a local condition number estimate on each processor and return the maximum over all processor of the estimate. Parameters: In  Trans -If true, solve transpose problem. Out  ConditionNumberEstimate - The maximum across all processors of the infinity-norm estimate of the condition number of the inverse of LDU. Implements Ifpack_Preconditioner.

int Ifpack_IC::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.

int Ifpack_IC::SetUseTranspose (  bool  UseTranspose_in  )  [inline, virtual]

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: In  UseTranspose_in -If true, multiply by the transpose of operator, otherwise just use operator. Returns: Always returns 0. Implements Epetra_Operator.

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

• Ifpack_IC.h
• Ifpack_IC.cpp

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