Package org.flag4j.linalg.decompositions.qr

Class RealQR

java.lang.Object

org.flag4j.linalg.decompositions.unitary.UnitaryDecomposition<Matrix,double[]>

org.flag4j.linalg.decompositions.unitary.RealUnitaryDecomposition

org.flag4j.linalg.decompositions.qr.RealQR

All Implemented Interfaces:

Decomposition<Matrix>

public class RealQR
extends RealUnitaryDecomposition

Instances of this class compute the QR decomposition of a real dense matrix.

The QR decomposition, decomposes a matrix A into an orthogonal matrix Q and an upper triangular matrix R such that A=QR.

Much of this code has been adapted from the EJML library.

Field Summary

Fields

Modifier and Type	Field	Description
protected final boolean	reduced	Flag indicating if the reduced (true) or full (false) QR decomposition should be computed.

Fields inherited from class org.flag4j.linalg.decompositions.unitary.RealUnitaryDecomposition

currentFactor, norm, shift

Fields inherited from class org.flag4j.linalg.decompositions.unitary.UnitaryDecomposition

applyUpdate, householderVector, minAxisSize, numCols, numRows, qFactors, storeReflectors, subDiagonal, transformData, transformMatrix, workArray

Constructor Summary

Constructors

Constructor	Description
RealQR()	Creates a QR decomposer.
RealQR(boolean reduced)	Creates a QR decomposer to compute either the full or reduced QR decomposition.

Method Summary

Modifier and Type	Method	Description
RealQR	decompose(Matrix src)	Computes the QR decomposition of a real dense matrix.
Matrix	getR()	Gets the upper triangular matrix R from the QR decomposition.
Matrix	getUpper()	Gets the upper triangular matrix R from the last decomposition.
protected Matrix	initQ()	Creates and initializes Q to the appropriately sized identity matrix.

Methods inherited from class org.flag4j.linalg.decompositions.unitary.RealUnitaryDecomposition

computeHouseholder, computePhasedNorm, findMaxAndInit, getQ, getUpper, initWorkArrays, updateData

Methods inherited from class org.flag4j.linalg.decompositions.unitary.UnitaryDecomposition

decomposeBase, setUp

Methods inherited from class java.lang.Object

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

Field Details

reduced

protected final boolean reduced

Flag indicating if the reduced (true) or full (false) QR decomposition should be computed.

Constructor Details

RealQR

public RealQR()

Creates a QR decomposer. This decomposer will compute the reduced QR decomposition.

See Also:

• RealQR(boolean)

RealQR

public RealQR(boolean reduced)

Creates a QR decomposer to compute either the full or reduced QR decomposition.

Parameters:

reduced - Flag indicating if this decomposer should compute the full or reduced QR decomposition.

Method Details

decompose

public RealQR decompose(Matrix src)

Computes the QR decomposition of a real dense matrix.

Parameters:

src - The source matrix to decompose.

Returns:

A reference to this decomposer.

initQ

protected Matrix initQ()

Creates and initializes Q to the appropriately sized identity matrix.

Specified by:

initQ in class UnitaryDecomposition<Matrix,double[]>

Returns:

An identity matrix with the appropriate size.

getUpper

public Matrix getUpper()

Gets the upper triangular matrix R from the last decomposition. Same as getR().

Specified by:

getUpper in class UnitaryDecomposition<Matrix,double[]>

Returns:

The upper triangular matrix from the last decomposition.

getR

public Matrix getR()

Gets the upper triangular matrix R from the QR decomposition.

Returns:

The upper triangular matrix R from the QR decomposition.