cern.colt.matrix.tfloat.algo.solver.preconditioner

Class FloatAMG

java.lang.Object

cern.colt.matrix.tfloat.algo.solver.preconditioner.FloatAMG

All Implemented Interfaces:

FloatPreconditioner

public class FloatAMG
extends java.lang.Object
implements FloatPreconditioner

Algebraic multigrid preconditioner. Uses the smoothed aggregation method described by Vanek, Mandel, and Brezina (1996).

Constructor Summary

Constructors

Constructor and Description
FloatAMG() Sets up the algebraic multigrid preconditioner using some default parameters.
FloatAMG(float omegaPreF, float omegaPreR, float omegaPostF, float omegaPostR, int nu1, int nu2, int gamma, int min, float omega) Sets up the algebraic multigrid preconditioner
FloatAMG(float omegaPre, float omegaPost, int nu1, int nu2, int gamma, int min, float omega) Sets up the algebraic multigrid preconditioner.

Method Summary

Modifier and Type	Method and Description
FloatMatrix1D	apply(FloatMatrix1D b, FloatMatrix1D x) Solves the approximate problem with the given right hand side.
void	setMatrix(FloatMatrix2D A) Sets the operator matrix for the preconditioner.
FloatMatrix1D	transApply(FloatMatrix1D b, FloatMatrix1D x) Solves the approximate transpose problem with the given right hand side.

Methods inherited from class java.lang.Object

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

Constructor Detail

FloatAMG

public FloatAMG(float omegaPreF,
                float omegaPreR,
                float omegaPostF,
                float omegaPostR,
                int nu1,
                int nu2,
                int gamma,
                int min,
                float omega)

Sets up the algebraic multigrid preconditioner

Parameters:

omegaPreF - Overrelaxation parameter in the forward sweep of the pre-smoothing

omegaPreR - Overrelaxation parameter in the backwards sweep of the pre-smoothing

omegaPostF - Overrelaxation parameter in the forward sweep of the post-smoothing

omegaPostR - Overrelaxation parameter in the backwards sweep of the post-smoothing

nu1 - Number of pre-relaxations to perform

nu2 - Number of post-relaxations to perform

gamma - Number of times to go to a coarser level

min - Smallest matrix size before using a direct solver

omega - Jacobi damping parameter, between zero and one. If it equals zero, the method reduces to the standard aggregate multigrid method

FloatAMG

public FloatAMG(float omegaPre,
                float omegaPost,
                int nu1,
                int nu2,
                int gamma,
                int min,
                float omega)

Sets up the algebraic multigrid preconditioner. Uses an SOR method, without the backward sweep in SSOR

Parameters:

omegaPre - Overrelaxation parameter in the pre-smoothing

omegaPost - Overrelaxation parameter in the post-smoothing

nu1 - Number of pre-relaxations to perform

nu2 - Number of post-relaxations to perform

gamma - Number of times to go to a coarser level

min - Smallest matrix size before using a direct solver

omega - Jacobi damping parameter, between zero and one. If it equals zero, the method reduces to the standard aggregate multigrid method

FloatAMG

public FloatAMG()

Sets up the algebraic multigrid preconditioner using some default parameters. In the presmoothing, omegaF=1 and omegaR=1.85, while in the postsmoothing, omegaF=1.85 and omegaR=1. Sets nu1=nu2=gamma=1, has a smallest matrix size of 40, and sets omega=2/3.

Method Detail

apply

public FloatMatrix1D apply(FloatMatrix1D b,
                           FloatMatrix1D x)

Description copied from interface: FloatPreconditioner

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

Specified by:

apply in interface FloatPreconditioner

Parameters:

b - Right hand side of problem

x - Result is stored here

Returns:

x

transApply

public FloatMatrix1D transApply(FloatMatrix1D b,
                                FloatMatrix1D x)

Description copied from interface: FloatPreconditioner

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

Specified by:

transApply in interface FloatPreconditioner

Parameters:

b - Right hand side of problem

x - Result is stored here

Returns:

x

setMatrix

public void setMatrix(FloatMatrix2D A)

Description copied from interface: FloatPreconditioner

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 FloatPreconditioner

Parameters:

A - Matrix to setup the preconditioner for. Not modified