org.biojava.nbio.structure.jama

Class EigenvalueDecomposition

java.lang.Object

org.biojava.nbio.structure.jama.EigenvalueDecomposition

All Implemented Interfaces:

Serializable

public class EigenvalueDecomposition
extends Object
implements 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().

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
EigenvalueDecomposition(Matrix Arg) Check for symmetry, then construct the eigenvalue decomposition Structure to access D and V.

Method Summary

Methods

Modifier and Type	Method and Description
Matrix	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
Matrix	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(Matrix Arg)

Check for symmetry, then construct the eigenvalue decomposition Structure to access D and V.

Parameters:

Arg - Square matrix

Method Detail

getV

public Matrix 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 Matrix getD()

Return the block diagonal eigenvalue matrix

Returns:

D