de.lmu.ifi.dbs.elki.math.linearalgebra

Class SortedEigenPairs

java.lang.Object

de.lmu.ifi.dbs.elki.math.linearalgebra.SortedEigenPairs

public class SortedEigenPairs
extends Object

Helper class which encapsulates an array of eigenpairs (i.e. an array of eigenvectors and their corresponding eigenvalues). This class is used to sort eigenvectors (and -values).

Author:

Elke Achtert

Field Summary

Fields

Modifier and Type	Field and Description
private EigenPair[]	eigenPairs The array of eigenpairs.

Constructor Summary

Constructors

Modifier	Constructor and Description
private	SortedEigenPairs() Creates a new empty SortedEigenPairs object.
	SortedEigenPairs(EigenvalueDecomposition evd, boolean ascending) Creates a new SortedEigenPairs object from the specified eigenvalue decomposition.
	SortedEigenPairs(List<EigenPair> eigenPairs) Creates a new SortedEigenPairs object from the specified list.

Method Summary

Methods

Modifier and Type	Method and Description
SortedEigenPairs	copy() Returns a deep copy of this object
double[]	eigenValues() Returns the sorted eigenvalues.
Matrix	eigenVectors() Returns the sorted eigenvectors.
Matrix	eigenVectors(int n) Returns the first n sorted eigenvectors as a matrix.
EigenPair	getEigenPair(int index) Returns the eigenpair at the specified index.
Matrix	reverseEigenVectors(int n) Returns the last n sorted eigenvectors as a matrix.
int	size() Returns the number of the eigenpairs.
String	toString() Returns a string representation of this EigenPair.

Methods inherited from class java.lang.Object

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

Field Detail

eigenPairs

private EigenPair[] eigenPairs

The array of eigenpairs.

Constructor Detail

SortedEigenPairs

private SortedEigenPairs()

Creates a new empty SortedEigenPairs object. Can only be called from the copy() method.

SortedEigenPairs

public SortedEigenPairs(EigenvalueDecomposition evd,
                boolean ascending)

Creates a new SortedEigenPairs object from the specified eigenvalue decomposition. The eigenvectors are sorted according to the specified order.

Parameters:

evd - the underlying eigenvalue decomposition

ascending - a boolean that indicates ascending order

SortedEigenPairs

public SortedEigenPairs(List<EigenPair> eigenPairs)

Creates a new SortedEigenPairs object from the specified list. The eigenvectors are sorted in descending order.

Parameters:

eigenPairs - the eigenpairs to be sorted

Method Detail

eigenValues

public double[] eigenValues()

Returns the sorted eigenvalues.

Returns:

the sorted eigenvalues

eigenVectors

public Matrix eigenVectors()

Returns the sorted eigenvectors.

Returns:

the sorted eigenvectors

eigenVectors

public Matrix eigenVectors(int n)

Returns the first n sorted eigenvectors as a matrix.

Parameters:

n - the number of eigenvectors (columns) to be returned

Returns:

the first n sorted eigenvectors

reverseEigenVectors

public Matrix reverseEigenVectors(int n)

Returns the last n sorted eigenvectors as a matrix.

Parameters:

n - the number of eigenvectors (columns) to be returned

Returns:

the last n sorted eigenvectors

getEigenPair

public EigenPair getEigenPair(int index)

Returns the eigenpair at the specified index.

Parameters:

index - the index of the eigenpair to be returned

Returns:

the eigenpair at the specified index

size

public int size()

Returns the number of the eigenpairs.

Returns:

the number of the eigenpairs

toString

public String toString()

Returns a string representation of this EigenPair.

Overrides:

toString in class Object

Returns:

a string representation of this EigenPair

copy

public SortedEigenPairs copy()

Returns a deep copy of this object

Returns:

new copy