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Ifpack_ICT Class Reference

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

#include <Ifpack_ICT.h>

Inheritance diagram for Ifpack_ICT:

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Collaboration diagram for Ifpack_ICT:
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List of all members.

Public Member Functions

 Ifpack_ICT (const Epetra_RowMatrix *A)
 Ifpack_ICT constuctor with variable number of indices per row.
virtual ~Ifpack_ICT ()
 Ifpack_ICT Destructor.
int SetParameters (Teuchos::ParameterList &parameterlis)
 Set parameters using a Teuchos::ParameterList object.
const Epetra_RowMatrix & Matrix () const
 Returns a reference to the matrix to be preconditioned.
bool IsInitialized () const
 Returns true is the preconditioner has been successfully initialized.
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.
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_ICT 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=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.
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_CrsMatrix & H () const
 Returns the address of the D factor associated with this factored matrix.
const char * Label () const
int SetLabel (const char *Label)
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 all applications of Compute().
virtual double ApplyInverseFlops () const
 Returns the number of flops in all applications of ApplyInverse().
double LevelOfFill () const
 Returns the level-of-fill.
double AbsoluteThreshold () const
 Returns the absolute threshold.
double RelativeThreshold () const
 Returns the relative threshold.
double RelaxValue () const
 Returns the relaxation value.
double DropTolerance () const
 Returns the drop threshold.
Additional methods required to support the Epetra_Operator interface.
int SetUseTranspose (bool UseTranspose)
 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.

Detailed Description

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

The Ifpack_ICT 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.

Definition at line 71 of file Ifpack_ICT.h.

Constructor & Destructor Documentation

Ifpack_ICT::Ifpack_ICT (  const Epetra_RowMatrix *  A  ) 
 

Ifpack_ICT constuctor with variable number of indices per row.

Creates a Ifpack_ICT object and allocates storage.

Parameters:
In A - User matrix to be factored.
In Graph - Graph generated by Ifpack_IlukGraph.

Definition at line 50 of file Ifpack_ICT.cpp.

Member Function Documentation

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

Returns the result of a Ifpack_ICT 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 405 of file Ifpack_ICT.cpp.

References Epetra_Time::ElapsedTime(), IsComputed(), Epetra_MultiVector::NumVectors(), Epetra_MultiVector::Pointers(), and Epetra_Time::ResetStartTime().

int Ifpack_ICT::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 145 of file Ifpack_ICT.cpp.

References AbsoluteThreshold(), Epetra_Operator::Comm(), Comm(), Copy, Epetra_Time::ElapsedTime(), Epetra_RowMatrix::ExtractMyRowCopy(), Initialize(), IsInitialized(), LevelOfFill(), Matrix(), Epetra_RowMatrix::MaxNumEntries(), Epetra_RowMatrix::Multiply(), Epetra_RowMatrix::NumMyRows(), Epetra_Comm::NumProc(), Epetra_MultiVector::Random(), RelativeThreshold(), RelaxValue(), Epetra_Time::ResetStartTime(), Epetra_RowMatrix::RowMatrixRowMap(), Epetra_Comm::SumAll(), and Epetra_MultiVector::Update().

double Ifpack_ICT::Condest (  const Ifpack_CondestType  CT = Ifpack_Cheap,
const int  MaxIters = 1550,
const double  Tol = 1e-9,
Epetra_RowMatrix *  Matrix = 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 453 of file Ifpack_ICT.cpp.

References IsComputed().

int Ifpack_ICT::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 123 of file Ifpack_ICT.cpp.

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

Referenced by Compute().

double Ifpack_ICT::LevelOfFill (   )  const [inline]
 

Returns the level-of-fill.

Note:
: if 1.0, then the factored matrix contains approximatively the same number of elements of A.

Definition at line 284 of file Ifpack_ICT.h.

Referenced by Compute(), Print(), and SetParameters().

int Ifpack_ICT::SetUseTranspose (  bool  UseTranspose  )  [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 -If true, multiply by the transpose of operator, otherwise just use operator.
Returns:
Always returns 0.

Implements Epetra_Operator.

Definition at line 191 of file Ifpack_ICT.h.

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