no.uib.cipr.matrix.sparse
Class SSOR

java.lang.Object
  extended by no.uib.cipr.matrix.sparse.SSOR
All Implemented Interfaces:
Preconditioner

public class SSOR
extends java.lang.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
SSOR(CompRowMatrix F)
          Constructor for SSOR.
SSOR(CompRowMatrix F, boolean reverse, double omegaF, double omegaR)
          Constructor for SSOR
 
Method Summary
 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