Ifpack Class Reference

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

#include <Ifpack.h>

List of all members.

Public Types
enum	parameter {   absolute_threshold, relative_threshold, drop_tolerance, fill_tolerance,   relax_value, level_fill, level_overlap, num_steps,   use_reciprocal, overlap_mode }
Public Member Functions
Ifpack_Preconditioner *	Create (const string PrecType, Epetra_RowMatrix *Matrix, const int overlap=0)
	Creates an instance of Ifpack_Preconditioner.
int	SetParameters (int argc, char *argv[], Teuchos::ParameterList &List, string &PrecType, int &Overlap)
	Sets the options in List from the command line.

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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, SNL 9214

Date:

Last updated on 25-Jan-05.

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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. Creates an Ifpack_Preconditioner. Parameters: PrecType  (In) - type of preconditioner to be created. Matrix  (In) - Matrix used to define the preconditioner overlap  (In) - specified overlap, defaulted to 0.

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

• Ifpack.h
• ifp_parameters.h
• Ifpack.cpp

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