org.ejml.simple

Class SimpleEVD<T extends SimpleMatrix>

java.lang.Object

org.ejml.simple.SimpleEVD<T>

public class SimpleEVD<T extends SimpleMatrix>
extends Object

Wrapper around EigenDecomposition for SimpleMatrix

Author:

Peter Abeles

Constructor Summary

Constructors

Constructor and Description
SimpleEVD(DenseMatrix64F mat)

Method Summary

Methods

Modifier and Type	Method and Description
Complex64F	getEigenvalue(int index) Returns an eigenvalue as a complex number.
T	getEigenVector(int index) Used to retrieve real valued eigenvectors.
EigenDecomposition	getEVD() Returns the underlying decomposition that this is a wrapper around.
int	getIndexMax() Returns the index of the eigenvalue which has the largest magnitude.
int	getIndexMin() Returns the index of the eigenvalue which has the smallest magnitude.
int	getNumberOfEigenvalues() Returns the number of eigenvalues/eigenvectors.
double	quality() Computes the quality of the computed decomposition.

Methods inherited from class java.lang.Object

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

Constructor Detail

SimpleEVD

public SimpleEVD(DenseMatrix64F mat)

Method Detail

getNumberOfEigenvalues

public int getNumberOfEigenvalues()

Returns the number of eigenvalues/eigenvectors. This is the matrix's dimension.

Returns:

number of eigenvalues/eigenvectors.

getEigenvalue

public Complex64F getEigenvalue(int index)

Returns an eigenvalue as a complex number. For symmetric matrices the returned eigenvalue will always be a real number, which means the imaginary component will be equal to zero.

NOTE: The order of the eigenvalues is dependent upon the decomposition algorithm used. This means that they may or may not be ordered by magnitude. For example the QR algorithm will returns results that are partially ordered by magnitude, but this behavior should not be relied upon.

Parameters:

index - Index of the eigenvalue eigenvector pair.

Returns:

An eigenvalue.

getEigenVector

public T getEigenVector(int index)

Used to retrieve real valued eigenvectors. If an eigenvector is associated with a complex eigenvalue then null is returned instead.

Parameters:

index - Index of the eigenvalue eigenvector pair.

Returns:

If the associated eigenvalue is real then an eigenvector is returned, null otherwise.

quality

public double quality()

Computes the quality of the computed decomposition. A value close to or less than 1e-15 is considered to be within machine precision.

This function must be called before the original matrix has been modified or else it will produce meaningless results.

Returns:

Quality of the decomposition.

getEVD

public EigenDecomposition getEVD()

Returns the underlying decomposition that this is a wrapper around.

Returns:

EigenDecomposition

getIndexMax

public int getIndexMax()

Returns the index of the eigenvalue which has the largest magnitude.

Returns:

index of the largest magnitude eigen value.

getIndexMin

public int getIndexMin()

Returns the index of the eigenvalue which has the smallest magnitude.

Returns:

index of the smallest magnitude eigen value.