Package org.ejml.dense.row.decomposition.eig

Class WatchedDoubleStepQRDecomposition_DDRM

java.lang.Object

org.ejml.dense.row.decomposition.eig.WatchedDoubleStepQRDecomposition_DDRM

All Implemented Interfaces:

DecompositionInterface<DMatrixRMaj>, EigenDecomposition<DMatrixRMaj>, EigenDecomposition_F64<DMatrixRMaj>

public class WatchedDoubleStepQRDecomposition_DDRM
extends Object
implements EigenDecomposition_F64<DMatrixRMaj>

Finds the eigenvalue decomposition of an arbitrary square matrix using the implicit double-step QR algorithm. Watched is included in its name because it is designed to print out internal debugging information. This class is still underdevelopment and has yet to be optimized.

Based off the description found in:
David S. Watkins, "Fundamentals of Matrix Computations." Second Edition.

Constructor Summary

Constructors

Constructor	Description
WatchedDoubleStepQRDecomposition_DDRM(boolean computeVectors)
WatchedDoubleStepQRDecomposition_DDRM(HessenbergSimilarDecomposition_DDRM hessenberg, WatchedDoubleStepQREigen_DDRM eigenQR, boolean computeVectors)

Method Summary

Modifier and Type	Method	Description
boolean	decompose(DMatrixRMaj A)	Computes the decomposition of the input matrix.
Complex_F64	getEigenvalue(int index)	Returns an eigenvalue as a complex number.
DMatrixRMaj	getEigenVector(int index)	Used to retrieve real valued eigenvectors.
int	getNumberOfEigenvalues()	Returns the number of eigenvalues/eigenvectors.
boolean	inputModified()	Checks if the input matrix to DecompositionInterface.decompose(org.ejml.data.Matrix) is modified during the decomposition process.

Methods inherited from class java.lang.Object

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

Constructor Details

WatchedDoubleStepQRDecomposition_DDRM

public WatchedDoubleStepQRDecomposition_DDRM(boolean computeVectors)

WatchedDoubleStepQRDecomposition_DDRM

public WatchedDoubleStepQRDecomposition_DDRM(HessenbergSimilarDecomposition_DDRM hessenberg,
 WatchedDoubleStepQREigen_DDRM eigenQR,
 boolean computeVectors)

Method Details

decompose

public boolean decompose(DMatrixRMaj A)

Description copied from interface: DecompositionInterface

Computes the decomposition of the input matrix. Depending on the implementation the input matrix might be stored internally or modified. If it is modified then the function DecompositionInterface.inputModified() will return true and the matrix should not be modified until the decomposition is no longer needed.

Specified by:

decompose in interface DecompositionInterface<DMatrixRMaj>

Parameters:

A - The matrix which is being decomposed. Modification is implementation dependent.

Returns:

Returns if it was able to decompose the matrix.

inputModified

public boolean inputModified()

Description copied from interface: DecompositionInterface

Checks if the input matrix to DecompositionInterface.decompose(org.ejml.data.Matrix) is modified during the decomposition process.

Specified by:

inputModified in interface DecompositionInterface<DMatrixRMaj>

Returns:

true if the input matrix to decompose() is modified.

getNumberOfEigenvalues

public int getNumberOfEigenvalues()

Description copied from interface: EigenDecomposition

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

Specified by:

getNumberOfEigenvalues in interface EigenDecomposition<DMatrixRMaj>

Returns:

number of eigenvalues/eigenvectors.

getEigenvalue

public Complex_F64 getEigenvalue(int index)

Description copied from interface: EigenDecomposition_F64

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.

Specified by:

getEigenvalue in interface EigenDecomposition_F64<DMatrixRMaj>

Parameters:

index - Index of the eigenvalue eigenvector pair.

Returns:

An eigenvalue.

getEigenVector

public DMatrixRMaj getEigenVector(int index)

Description copied from interface: EigenDecomposition

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

Specified by:

getEigenVector in interface EigenDecomposition<DMatrixRMaj>

Parameters:

index - Index of the eigenvalue eigenvector pair.

Returns:

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