org.ejml.alg.dense.decomposition.lu
Class LUDecompositionBase

java.lang.Object
  org.ejml.alg.dense.decomposition.lu.LUDecompositionBase

All Implemented Interfaces:

DecompositionInterface<DenseMatrix64F>, LUDecomposition<DenseMatrix64F>

Direct Known Subclasses:

LUDecompositionAlt, LUDecompositionNR

public abstract class LUDecompositionBase
extends Object
implements LUDecomposition<DenseMatrix64F>

Contains common data structures and operations for LU decomposition algorithms.

Author:

Peter Abeles

Field Summary

protected double[]	dataLU
protected int[]	indx
protected DenseMatrix64F	LU
protected int	m
protected int	maxWidth
protected int	n
protected int[]	pivot
protected double	pivsign
protected double[]	vv

Constructor Summary

LUDecompositionBase()

Method Summary

double[]	_getVV()
void	_solveVectorInternal(double[] vv) a specialized version of solve that avoid additional checks that are not needed.
double	computeDeterminant() Computes the determinant from the LU decomposition.
protected void	decomposeCommonInit(DenseMatrix64F a)
int[]	getIndx()
DenseMatrix64F	getLower(DenseMatrix64F lower) Writes the lower triangular matrix into the specified matrix.
DenseMatrix64F	getLU()
int[]	getPivot()
DenseMatrix64F	getPivot(DenseMatrix64F pivot) For numerical stability there are often row interchanges.
DenseMatrix64F	getUpper(DenseMatrix64F upper) Writes the upper triangular matrix into the specified matrix.
boolean	inputModified() Is the input matrix to DecompositionInterface.decompose(org.ejml.data.Matrix64F) is modified during the decomposition process.
boolean	isSingular() Determines if the decomposed matrix is singular.
double	quality()
void	setExpectedMaxSize(int numRows, int numCols)

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.ejml.alg.dense.decomposition.DecompositionInterface

decompose

Field Detail

LU

protected DenseMatrix64F LU

maxWidth

protected int maxWidth

m

protected int m

n

protected int n

dataLU

protected double[] dataLU

vv

protected double[] vv

indx

protected int[] indx

pivot

protected int[] pivot

pivsign

protected double pivsign

Constructor Detail

LUDecompositionBase

public LUDecompositionBase()

Method Detail

setExpectedMaxSize

public void setExpectedMaxSize(int numRows,
                               int numCols)

getLU

public DenseMatrix64F getLU()

getIndx

public int[] getIndx()

getPivot

public int[] getPivot()

inputModified

public boolean inputModified()

Description copied from interface: DecompositionInterface

Is the input matrix to DecompositionInterface.decompose(org.ejml.data.Matrix64F) is modified during the decomposition process.

Specified by:

inputModified in interface DecompositionInterface<DenseMatrix64F>

Returns:

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

getLower

public DenseMatrix64F getLower(DenseMatrix64F lower)

Writes the lower triangular matrix into the specified matrix.

Specified by:

getLower in interface LUDecomposition<DenseMatrix64F>

Parameters:

lower - Where the lower triangular matrix is writen to.

Returns:

The L matrix.

getUpper

public DenseMatrix64F getUpper(DenseMatrix64F upper)

Writes the upper triangular matrix into the specified matrix.

Specified by:

getUpper in interface LUDecomposition<DenseMatrix64F>

Parameters:

upper - Where the upper triangular matrix is writen to.

Returns:

The U matrix.

getPivot

public DenseMatrix64F getPivot(DenseMatrix64F pivot)

Description copied from interface: LUDecomposition

For numerical stability there are often row interchanges. This computes a pivot matrix that will undo those changes.

Specified by:

getPivot in interface LUDecomposition<DenseMatrix64F>

decomposeCommonInit

protected void decomposeCommonInit(DenseMatrix64F a)

isSingular

public boolean isSingular()

Determines if the decomposed matrix is singular. This function can return false and the matrix be almost singular, which is still bad.

Specified by:

isSingular in interface LUDecomposition<DenseMatrix64F>

Returns:

true if singular false otherwise.

computeDeterminant

public double computeDeterminant()

Computes the determinant from the LU decomposition.

Specified by:

computeDeterminant in interface LUDecomposition<DenseMatrix64F>

Returns:

The matrix's determinant.

quality

public double quality()

_solveVectorInternal

public void _solveVectorInternal(double[] vv)

a specialized version of solve that avoid additional checks that are not needed.

_getVV

public double[] _getVV()