Ifpack Class Reference

Ifpack: a function class to define Ifpack preconditioners. More...

#include <Ifpack.h>

List of all members.

Public Types
enum	EPrecType {   POINT_RELAXATION, POINT_RELAXATION_STAND_ALONE, BLOCK_RELAXATION, BLOCK_RELAXATION_STAND_ALONE,   BLOCK_RELAXATION_STAND_ALONE_ILU, BLOCK_RELAXATION_STAND_ALONE_AMESOS, BLOCK_RELAXATION_AMESOS, AMESOS,   AMESOS_STAND_ALONE, IC, IC_STAND_ALONE, ICT,   ICT_STAND_ALONE, ILU, ILU_STAND_ALONE, ILUT,   ILUT_STAND_ALONE, CHEBYSHEV }
	Enum for the type of preconditioner. More...
Public Member Functions
Ifpack_Preconditioner *	Create (const string PrecType, Epetra_RowMatrix *Matrix, const int overlap=0)
	Creates an instance of Ifpack_Preconditioner given the string name of the preconditioner type (can fail with bad input).
int	SetParameters (int argc, char *argv[], Teuchos::ParameterList &List, string &PrecType, int &Overlap)
	Sets the options in List from the command line.
Static Public Member Functions
static const char *	toString (const EPrecType precType)
	Function that gives the string name for preconditioner given its enumerication value.
static Ifpack_Preconditioner *	Create (EPrecType PrecType, Epetra_RowMatrix *Matrix, const int overlap=0)
	Creates an instance of Ifpack_Preconditioner given the enum value of the preconditioner type (can not fail, no bad input possible).
Static Public Attributes
static const int	numPrecTypes
static const EPrecType	precTypeValues [numPrecTypes]
	List of the preconditioner types as enum values .
static const char *	precTypeNames [numPrecTypes]
	List of preconditioner types as string values.
static const bool	supportsUnsymmetric [numPrecTypes]
	List of bools that determines if the precondtioner type supports unsymmetric matrices.

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Detailed Description

Ifpack: a function class to define Ifpack preconditioners.

Class Ifpack is a function class, that contains just one method: Create(). Using Create(), users can easily define a variety of IFPACK preconditioners.

Create requires 3 arguments:

• a string, indicating the preconditioner to be built;
• a pointer to an Epetra_RowMatrix, representing the matrix to be used to define the preconditioner;
• an interger (defaulted to 0), that specifies the amount of overlap among the processes.

The first argument can assume the following values:

• "point relaxation" : returns an instance of Ifpack_AdditiveSchwarz<Ifpack_PointRelaxation>
• "point relaxation stand-alone" : returns an instance of Ifpack_PointRelaxation (value of overlap is ignored).
• "block relaxation" : returns an instance of Ifpack_AdditiveSchwarz<Ifpack_BlockRelaxation>
• "block relaxation stand-alone)" : returns an instance of Ifpack_BlockRelaxation.
• "Amesos" : returns an instance of Ifpack_AdditiveSchwarz<Ifpack_Amesos>.
• "Amesos" : returns an instance of Ifpack_Amesos.
• "IC" : returns an instance of Ifpack_AdditiveSchwarz<Ifpack_IC>.
• "IC stand-alone" : returns an instance of Ifpack_AdditiveSchwarz<Ifpack_IC>.
• "ICT" : returns an instance of Ifpack_AdditiveSchwarz<Ifpack_ICT>.
• "ICT stand-alone" : returns an instance of Ifpack_ICT.
• "ILU" : returns an instance of Ifpack_AdditiveSchwarz<Ifpack_ILU>.
• "ILU stand-alone" : returns an instance of Ifpack_ILU.
• "ILUT" : returns an instance of Ifpack_AdditiveSchwarz<Ifpack_ILUT>.
• "ILUT stand-alone" : returns an instance of Ifpack_ILUT.
• otherwise, Create() returns 0.

Note:

Objects in stand-alone mode cannot use reordering, variable overlap, and singleton filters. However, their construction can be slightly faster than the non stand-alone counterpart.

The following fragment of code shows the basic usage of this class.

#include "Ifpack.h"

...

Ifpack Factory;

Epetra_RowMatrix* A; // A is FillComplete()'d.
string PrecType = "ILU"; // use incomplete LU on each process
int OverlapLevel = 1; // one row of overlap among the processes
Ifpack_Preconditioner* Prec = Factory.Create(PrecType, A, OverlapLevel);
assert (Prec != 0);

Teuchos::ParameterList List;
List.set("fact: level-of-fill", 5); // use ILU(5)

IFPACK_CHK_ERR(Prec->SetParameters(List));
IFPACK_CHK_ERR(Prec->Initialize());
IFPACK_CHK_ERR(Prec->Compute());

// now Prec can be used as AztecOO preconditioner
// like for instance
AztecOO AztecOOSolver(*Problem);

// specify solver
AztecOOSolver.SetAztecOption(AZ_solver,AZ_gmres);
AztecOOSolver.SetAztecOption(AZ_output,32);

// Set Prec as preconditioning operator
AztecOOSolver.SetPrecOperator(Prec);

// Call the solver
AztecOOSolver.Iterate(1550,1e-8);

// print information on stdout
cout << *Prec;

// delete the preconditioner
delete Prec;

Author:

Marzio Sala, (formally) SNL org. 1414

Date:

Last updated on 25-Jan-05.

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Member Enumeration Documentation

enum Ifpack::EPrecType

Enum for the type of preconditioner.

Enumerator:

POINT_RELAXATION
POINT_RELAXATION_STAND_ALONE
BLOCK_RELAXATION
BLOCK_RELAXATION_STAND_ALONE
BLOCK_RELAXATION_STAND_ALONE_ILU
BLOCK_RELAXATION_STAND_ALONE_AMESOS
BLOCK_RELAXATION_AMESOS
AMESOS
AMESOS_STAND_ALONE
IC
IC_STAND_ALONE
ICT
ICT_STAND_ALONE
ILU
ILU_STAND_ALONE
ILUT
ILUT_STAND_ALONE
CHEBYSHEV

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Member Function Documentation

Ifpack_Preconditioner* Ifpack::Create	(	const string	PrecType,
		Epetra_RowMatrix *	Matrix,
		const int	overlap = 0
	)

Creates an instance of Ifpack_Preconditioner given the string name of the preconditioner type (can fail with bad input).

Parameters:

	PrecType	(In) - String name of preconditioner type to be created.
	Matrix	(In) - Matrix used to define the preconditioner
	overlap	(In) - specified overlap, defaulted to 0.

Returns 0 if the preconditioner with that input name does not exist. Otherwise, return a newly created preconditioner object. Note that the client is responsible for calling delete on the returned object once it is finished using it!

static Ifpack_Preconditioner* Ifpack::Create	(	EPrecType	PrecType,
		Epetra_RowMatrix *	Matrix,
		const int	overlap = 0
	)			[static]

Creates an instance of Ifpack_Preconditioner given the enum value of the preconditioner type (can not fail, no bad input possible).

Parameters:

	PrecType	(In) - Enum value of preconditioner type to be created.
	Matrix	(In) - Matrix used to define the preconditioner
	overlap	(In) - specified overlap, defaulted to 0.

int Ifpack::SetParameters	(	int	argc,
		char *	argv[],
		Teuchos::ParameterList &	List,
		string &	PrecType,
		int &	Overlap
	)

Sets the options in List from the command line.

Note: If you want full support for all parameters, consider reading in a parameter list from an XML file as supported by the Teuchos helper function Teuchos::updateParametersFromXmlFile() or Teuchos::updateParametersFromXmlStream().

static const char* Ifpack::toString

(

const EPrecType

precType

)

[inline, static]

Function that gives the string name for preconditioner given its enumerication value.

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Member Data Documentation

const int Ifpack::numPrecTypes [static]

Initial value:

    +5

    +4

    +8



    +1

const char* Ifpack::precTypeNames[numPrecTypes] [static]

List of preconditioner types as string values.

const EPrecType Ifpack::precTypeValues[numPrecTypes] [static]

List of the preconditioner types as enum values .

const bool Ifpack::supportsUnsymmetric[numPrecTypes] [static]

List of bools that determines if the precondtioner type supports unsymmetric matrices.

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

• Ifpack.h