org.ejml.ops

Class CSpecializedOps

java.lang.Object

org.ejml.ops.CSpecializedOps

public class CSpecializedOps
extends java.lang.Object

Constructor Summary

Constructors

Constructor and Description
CSpecializedOps()

Method Summary

Modifier and Type	Method and Description
static org.ejml.data.CDenseMatrix64F	createReflector(org.ejml.data.CDenseMatrix64F u) Creates a reflector from the provided vector. Q = I - γ u uT γ = 2/||u||2
static org.ejml.data.CDenseMatrix64F	createReflector(org.ejml.data.CDenseMatrix64F u, double gamma) Creates a reflector from the provided vector and gamma. Q = I - γ u uH
static double	elementDiagMaxMagnitude2(org.ejml.data.CDenseMatrix64F a) Returns the magnitude squared of the complex element along the diagonal with the largest magnitude Max{ |aij|^2 } for all i and j
static org.ejml.data.CDenseMatrix64F	householder(org.ejml.data.CDenseMatrix64F u, double gamma) Q = I - gamma*u*uH
static org.ejml.data.CDenseMatrix64F	householderVector(org.ejml.data.CDenseMatrix64F x) Computes the householder vector used in QR decomposition.
static org.ejml.data.CDenseMatrix64F	pivotMatrix(org.ejml.data.CDenseMatrix64F ret, int[] pivots, int numPivots, boolean transposed) Creates a pivot matrix that exchanges the rows in a matrix: A' = P*A
static double	qualityTriangular(org.ejml.data.CDenseMatrix64F T) Computes the quality of a triangular matrix, where the quality of a matrix is defined in LinearSolver.quality().

Methods inherited from class java.lang.Object

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

Constructor Detail

CSpecializedOps

public CSpecializedOps()

Method Detail

createReflector

public static org.ejml.data.CDenseMatrix64F createReflector(org.ejml.data.CDenseMatrix64F u)

Creates a reflector from the provided vector.

Q = I - γ u u^T
γ = 2/||u||²

Parameters:

u - A vector. Not modified.

Returns:

An orthogonal reflector.

createReflector

public static org.ejml.data.CDenseMatrix64F createReflector(org.ejml.data.CDenseMatrix64F u,
                                                            double gamma)

Creates a reflector from the provided vector and gamma.

Q = I - γ u u^H

Parameters:

u - A vector. Not modified.

gamma - To produce a reflector gamma needs to be equal to 2/||u||.

Returns:

An orthogonal reflector.

pivotMatrix

public static org.ejml.data.CDenseMatrix64F pivotMatrix(org.ejml.data.CDenseMatrix64F ret,
                                                        int[] pivots,
                                                        int numPivots,
                                                        boolean transposed)

Creates a pivot matrix that exchanges the rows in a matrix:
A' = P*A

For example, if element 0 in 'pivots' is 2 then the first row in A' will be the 3rd row in A.

Parameters:

ret - If null then a new matrix is declared otherwise the results are written to it. Is modified.

pivots - Specifies the new order of rows in a matrix.

numPivots - How many elements in pivots are being used.

transposed - If the transpose of the matrix is returned.

Returns:

A pivot matrix.

elementDiagMaxMagnitude2

public static double elementDiagMaxMagnitude2(org.ejml.data.CDenseMatrix64F a)

Returns the magnitude squared of the complex element along the diagonal with the largest magnitude

Max{ |a_ij|^2 } for all i and j

Parameters:

a - A matrix. Not modified.

Returns:

The max magnitude squared

qualityTriangular

public static double qualityTriangular(org.ejml.data.CDenseMatrix64F T)

Computes the quality of a triangular matrix, where the quality of a matrix is defined in LinearSolver.quality(). In this situation the quality is the magnitude of the product of each diagonal element divided by the magnitude of the largest diagonal element. If all diagonal elements are zero then zero is returned.

Returns:

the quality of the system.

householder

public static org.ejml.data.CDenseMatrix64F householder(org.ejml.data.CDenseMatrix64F u,
                                                        double gamma)

Q = I - gamma*u*u^H

householderVector

public static org.ejml.data.CDenseMatrix64F householderVector(org.ejml.data.CDenseMatrix64F x)

Computes the householder vector used in QR decomposition. u = x / max(x) u(0) = u(0) + |u| u = u / u(0)

Parameters:

x - Input vector. Unmodified.

Returns:

The found householder reflector vector