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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>

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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_RowMatrixMatrix () const
Returns a pointer to the matrix to be preconditioned.
Epetra_RowMatrixMatrix ()
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.
long long NumGlobalNonzeros64 () const
int NumMyNonzeros () const
Returns the number of nonzero entries in the local graph.
const Epetra_VectorD () const
Returns the address of the D factor associated with this factored matrix.
const Epetra_CrsMatrixU () 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.
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_MapOperatorDomainMap () const
Returns the Epetra_Map object associated with the domain of this operator.
const Epetra_MapOperatorRangeMap () const
Returns the Epetra_Map object associated with the range of this operator.
const Epetra_CommComm () const
Returns the Epetra_BlockMap object associated with the range of this matrix operator.

## 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 (not level) based incomplete LDL^T factorization of a given Epetra_RowMatrix. The factorization that is produced is a function of several parameters:

1. Level of fill ratio. This defines the maximum number of entries per row/column in the factor, relative to the average number of nonzeros per row/col in A. The default value of 1.0 keeps the IC factor as sparse as A.

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.

Definition at line 80 of file Ifpack_IC.h.

## 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.

Definition at line 61 of file Ifpack_IC.cpp.

References SetParameters().

## 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.

Definition at line 309 of file Ifpack_IC.cpp.

 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:

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

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

Implements Ifpack_Preconditioner.

Definition at line 214 of file Ifpack_IC.cpp.

 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.

Definition at line 370 of file Ifpack_IC.cpp.

References IsComputed().

 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.

Definition at line 126 of file Ifpack_IC.cpp.

Referenced by Compute().

 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.

Definition at line 230 of file Ifpack_IC.h.

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