no.uib.cipr.matrix.sparse

Class ILUT

java.lang.Object

no.uib.cipr.matrix.sparse.ILUT

All Implemented Interfaces:

Preconditioner

public class ILUT
extends Object
implements Preconditioner

ILU preconditioner with fill-in. Uses the dual threshold approach of Saad.

Constructor Summary

Constructors

Constructor and Description
ILUT(FlexCompRowMatrix LU) Sets up the preconditioner for the given matrix.
ILUT(FlexCompRowMatrix LU, double tau, int p) Sets up the preconditioner for the given matrix

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.
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

ILUT

public ILUT(FlexCompRowMatrix LU,
            double tau,
            int p)

Sets up the preconditioner for the given matrix

Parameters:

LU - Matrix to use internally. For best performance, its non-zero pattern should conform to that of the system matrix

tau - Drop tolerance

p - Number of entries to keep on each row in of the factored matrix. This is in addition to the entries of the original matrix

ILUT

public ILUT(FlexCompRowMatrix LU)

Sets up the preconditioner for the given matrix. Uses a drop-tolerance of 10^-6, and keeps 50 entries on each row, including the main diagonal and any previous entries in the matrix structure

Parameters:

LU - Matrix to use internally. For best performance, its non-zero pattern should conform to that of the system matrix

Method Detail

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

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