Maths

Class EigenvalueDecomposition

java.lang.Object

Maths.EigenvalueDecomposition

All Implemented Interfaces:

java.io.Serializable

public class EigenvalueDecomposition
extends java.lang.Object
implements java.io.Serializable

Eigenvalues and eigenvectors of a real matrix.

If A is symmetric, then A = V*D*V' where the eigenvalue matrix D is diagonal and the eigenvector matrix V is orthogonal. I.e. A = V.times(D.times(V.transpose())) and V.times(V.transpose()) equals the identity matrix.

If A is not symmetric, then the eigenvalue matrix D is block diagonal with the real eigenvalues in 1-by-1 blocks and any complex eigenvalues, lambda + i*mu, in 2-by-2 blocks, [lambda, mu; -mu, lambda]. The columns of V represent the eigenvectors in the sense that A*V = V*D, i.e. A.times(V) equals V.times(D). The matrix V may be badly conditioned, or even singular, so the validity of the equation A = V*D*inverse(V) depends upon V.cond().

Taken from the public domain JAMA

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	EigenvalueDecomposition.ConvergenceException Exception for when the Eigendecomposition does not converge

Constructor Summary

Constructors

Constructor and Description
EigenvalueDecomposition(SquareMatrix Arg) Check for symmetry, then construct the eigenvalue decomposition

Method Summary

Methods

Modifier and Type	Method and Description
SquareMatrix	getD() Return the block diagonal eigenvalue matrix
double[]	getImagEigenvalues() Return the imaginary parts of the eigenvalues
double[]	getRealEigenvalues() Return the real parts of the eigenvalues
SquareMatrix	getV() Return the eigenvector matrix

Methods inherited from class java.lang.Object

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

Constructor Detail

EigenvalueDecomposition

public EigenvalueDecomposition(SquareMatrix Arg)
                        throws EigenvalueDecomposition.ConvergenceException

Check for symmetry, then construct the eigenvalue decomposition

Parameters:

Arg - Square matrix

Throws:

EigenvalueDecomposition.ConvergenceException - If the Eigendecomposition does not converge

Method Detail

getV

public SquareMatrix getV()

Return the eigenvector matrix

Returns:

V

getRealEigenvalues

public double[] getRealEigenvalues()

Return the real parts of the eigenvalues

Returns:

real(diag(D))

getImagEigenvalues

public double[] getImagEigenvalues()

Return the imaginary parts of the eigenvalues

Returns:

imag(diag(D))

getD

public SquareMatrix getD()

Return the block diagonal eigenvalue matrix

Returns:

D