maspack.solvers

Class CGSolver

java.lang.Object

maspack.solvers.CGSolver

All Implemented Interfaces:

IterativeSolver

public class CGSolver
extends java.lang.Object
implements IterativeSolver

Solves linear systems using the conjugate gradient algorithm

Nested Class Summary

Nested classes/interfaces inherited from interface maspack.solvers.IterativeSolver

IterativeSolver.ToleranceType

Field Summary

Fields

Modifier and Type	Field and Description
boolean	debug

Constructor Summary

Constructors

Constructor and Description
CGSolver()

Method Summary

Modifier and Type	Method and Description
int	getMaxIterations()
int	getNumIterations() Returns the number of iterations associated with the last call to solve.
double	getRelativeResidual() Returns the relative residual ||A x - b||/||b|| at the end of the last call to solve.
double	getTolerance()
IterativeSolver.ToleranceType	getToleranceType()
boolean	isCompatible(int matrixType)
void	setMaxIterations(int max)
void	setTolerance(double tol)
void	setToleranceType(IterativeSolver.ToleranceType type)
boolean	solve(VectorNd x, LinearTransformNd A, VectorNd b) Solves a linear system A x = b using the conjugate gradient method.
boolean	solve(VectorNd x, LinearTransformNd A, VectorNd b, double tol, int maxIter) Solves a linear system A x = b using the conjugate gradient method.
boolean	solve(VectorNd x, LinearTransformNd A, VectorNd b, double tol, int maxIter, LinearTransformNd P) Solves a linear system A x = b using the conjugate gradient method with a preconditioner.
boolean	solveTransformed(VectorNd x, SparseMatrixNd A, VectorNd b, double tol, int maxIter, IncompleteCholeskyDecomposition icd)

Methods inherited from class java.lang.Object

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

Field Detail

debug

public boolean debug

Constructor Detail

CGSolver

public CGSolver()

Method Detail

getTolerance

public double getTolerance()

Specified by:

getTolerance in interface IterativeSolver

setTolerance

public void setTolerance(double tol)

Specified by:

setTolerance in interface IterativeSolver

getToleranceType

public IterativeSolver.ToleranceType getToleranceType()

Specified by:

getToleranceType in interface IterativeSolver

setToleranceType

public void setToleranceType(IterativeSolver.ToleranceType type)

Specified by:

setToleranceType in interface IterativeSolver

getMaxIterations

public int getMaxIterations()

Specified by:

getMaxIterations in interface IterativeSolver

setMaxIterations

public void setMaxIterations(int max)

Specified by:

setMaxIterations in interface IterativeSolver

solve

public boolean solve(VectorNd x,
                     LinearTransformNd A,
                     VectorNd b)

Solves a linear system A x = b using the conjugate gradient method. The matrix associated with the linear system is represented implicitly by a LinearTransformNd. The method will iterate while relative residual ||A x - b||/||b|| is greater than a supplied tolerance and the number of iterations is less than a specified maximum.

Specified by:

solve in interface IterativeSolver

Parameters:

x - result vector, as well as initial guess of the solution

A - linear transform for the system to be solved

b - input vector

Returns:

true if a solution was found within the specified tolerance

solve

public boolean solve(VectorNd x,
                     LinearTransformNd A,
                     VectorNd b,
                     double tol,
                     int maxIter)

Solves a linear system A x = b using the conjugate gradient method. The matrix associated with the linear system is represented implicitly by a LinearTransformNd. The method will iterate while relative residual ||A x - b||/||b|| is greater than a supplied tolerance and the number of iterations is less than a specified maximum.

Parameters:

x - result vector, as well as initial guess of the solution

A - linear transform for the system to be solved

b - input vector

tol - solution tolerance

maxIter - maximum number of iferations

Returns:

true if a solution was found within the specified tolerance

solve

public boolean solve(VectorNd x,
                     LinearTransformNd A,
                     VectorNd b,
                     double tol,
                     int maxIter,
                     LinearTransformNd P)

Solves a linear system A x = b using the conjugate gradient method with a preconditioner. The matrix associated with the linear system and the preconditioner are each represented implicitly by a LinearTransformNd. The mul method of the preconditioner should implement the transformation y = inv(M) x, where M is a a preconditioning matrix that approximates A. The method will iterate while relative residual ||A x - b||/||b|| is greater than a supplied tolerance and the number of iterations is less than a specified maximum.

Parameters:

x - result vector, as well as initial guess of the solution

A - linear transform for the system to be solved

b - input vector

tol - solution tolerance

maxIter - maximum number of iferations

P - preconditioner (optional, may be specified as null)

Returns:

true if a solution was found within the specified tolerance

getNumIterations

public int getNumIterations()

Returns the number of iterations associated with the last call to solve.

Specified by:

getNumIterations in interface IterativeSolver

Returns:

number of iterations

getRelativeResidual

public double getRelativeResidual()

Returns the relative residual ||A x - b||/||b|| at the end of the last call to solve.

Specified by:

getRelativeResidual in interface IterativeSolver

Returns:

last relative residual

isCompatible

public boolean isCompatible(int matrixType)

Specified by:

isCompatible in interface IterativeSolver

solveTransformed

public boolean solveTransformed(VectorNd x,
                                SparseMatrixNd A,
                                VectorNd b,
                                double tol,
                                int maxIter,
                                IncompleteCholeskyDecomposition icd)