weka.core.matrix

Class CholeskyDecomposition

java.lang.Object

weka.core.matrix.CholeskyDecomposition

All Implemented Interfaces:

java.io.Serializable, RevisionHandler

public class CholeskyDecomposition
extends java.lang.Object
implements java.io.Serializable, RevisionHandler

Cholesky Decomposition.

For a symmetric, positive definite matrix A, the Cholesky decomposition is an lower triangular matrix L so that A = L*L'.

If the matrix is not symmetric or positive definite, the constructor returns a partial decomposition and sets an internal flag that may be queried by the isSPD() method.

Adapted from the JAMA package.

Version:

$Revision: 1.5 $

Author:

The Mathworks and NIST, Fracpete (fracpete at waikato dot ac dot nz)

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
CholeskyDecomposition(Matrix Arg) Cholesky algorithm for symmetric and positive definite matrix.

Method Summary

Modifier and Type	Method and Description
Matrix	getL() Return triangular factor.
java.lang.String	getRevision() Returns the revision string.
boolean	isSPD() Is the matrix symmetric and positive definite?
Matrix	solve(Matrix B) Solve A*X = B

Methods inherited from class java.lang.Object

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

Constructor Detail

CholeskyDecomposition

public CholeskyDecomposition(Matrix Arg)

Cholesky algorithm for symmetric and positive definite matrix.

Parameters:

Arg - Square, symmetric matrix.

Method Detail

isSPD

public boolean isSPD()

Is the matrix symmetric and positive definite?

Returns:

true if A is symmetric and positive definite.

getL

public Matrix getL()

Return triangular factor.

Returns:

L

solve

public Matrix solve(Matrix B)

Solve A*X = B

Parameters:

B - A Matrix with as many rows as A and any number of columns.

Returns:

X so that L*L'*X = B

Throws:

java.lang.IllegalArgumentException - Matrix row dimensions must agree.

java.lang.RuntimeException - Matrix is not symmetric positive definite.

getRevision

public java.lang.String getRevision()

Returns the revision string.

Specified by:

getRevision in interface RevisionHandler

Returns:

the revision