no.uib.cipr.matrix.sparse

Class SSOR

java.lang.Object

no.uib.cipr.matrix.sparse.SSOR

All Implemented Interfaces:

Preconditioner

public class SSOR
extends Object
implements Preconditioner

SSOR preconditioner. Uses symmetrical sucessive overrelaxation as a preconditioner. Meant for symmetrical, positive definite matrices. For best performance, omega must be carefully chosen (between 0 and 2).

Constructor Summary

Constructors

Constructor and Description
SSOR(CompRowMatrix F) Constructor for SSOR.
SSOR(CompRowMatrix F, boolean reverse, double omegaF, double omegaR) Constructor for SSOR

Method Summary

Modifier and Type	Method and Description
Vector	apply(Vector b, Vector x) Solves the approximate problem with the given right hand side.
void	setMatrix(Matrix A) Sets the operator matrix for the preconditioner.
void	setOmega(double omegaF, double omegaR) Sets the overrelaxation parameters
Vector	transApply(Vector b, Vector x) Solves the approximate transpose problem with the given right hand side.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SSOR

public SSOR(CompRowMatrix F,
            boolean reverse,
            double omegaF,
            double omegaR)

Constructor for SSOR

Parameters:

F - Matrix to use internally. It will not be modified, thus the system matrix may be passed

reverse - True to perform a reverse sweep as well as the forward sweep. If false, this preconditioner becomes the SOR method instead

omegaF - Overrelaxation parameter for the forward sweep. Between 0 and 2.

omegaR - Overrelaxation parameter for the backwards sweep. Between 0 and 2.

SSOR

public SSOR(CompRowMatrix F)

Constructor for SSOR. Uses omega=1 with a backwards sweep

Parameters:

F - Matrix to use internally. It will not be modified, thus the system matrix may be passed

Method Detail

setOmega

public void setOmega(double omegaF,
                     double omegaR)

Sets the overrelaxation parameters

Parameters:

omegaF - Overrelaxation parameter for the forward sweep. Between 0 and 2.

omegaR - Overrelaxation parameter for the backwards sweep. Between 0 and 2.

setMatrix

public void setMatrix(Matrix A)

Description copied from interface: Preconditioner

Sets the operator matrix for the preconditioner. This method must be called before a preconditioner is used by an iterative solver

Specified by:

setMatrix in interface Preconditioner

Parameters:

A - Matrix to setup the preconditioner for. Not modified

apply

public Vector apply(Vector b,
                    Vector x)

Description copied from interface: Preconditioner

Solves the approximate problem with the given right hand side. Result is stored in given solution vector

Specified by:

apply in interface Preconditioner

Parameters:

b - Right hand side of problem

x - Result is stored here

Returns:

x

transApply

public Vector transApply(Vector b,
                         Vector x)

Description copied from interface: Preconditioner

Solves the approximate transpose problem with the given right hand side. Result is stored in given solution vector

Specified by:

transApply in interface Preconditioner

Parameters:

b - Right hand side of problem

x - Result is stored here

Returns:

x