Package org.apache.commons.math4.linear

Class DiagonalMatrix

java.lang.Object

org.apache.commons.math4.linear.RealLinearOperator

org.apache.commons.math4.linear.AbstractRealMatrix

org.apache.commons.math4.linear.DiagonalMatrix

All Implemented Interfaces:

java.io.Serializable, AnyMatrix, RealMatrix

public class DiagonalMatrix
extends AbstractRealMatrix
implements java.io.Serializable

Implementation of a diagonal matrix.

Since:

3.1.1

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor	Description
DiagonalMatrix(double[] d)	Creates a matrix using the input array as the underlying data.
DiagonalMatrix(double[] d, boolean copyArray)	Creates a matrix using the input array as the underlying data.
DiagonalMatrix(int dimension)	Creates a matrix with the supplied dimension.

Method Summary

Modifier and Type	Method	Description
DiagonalMatrix	add(DiagonalMatrix m)	Compute the sum of this and m.
void	addToEntry(int row, int column, double increment)	Adds (in place) the specified value to the specified entry of this matrix.
RealMatrix	copy()	Returns a (deep) copy of this.
RealMatrix	createMatrix(int rowDimension, int columnDimension)	Create a new RealMatrix of the same type as the instance with the supplied row and column dimensions.
int	getColumnDimension()	Returns the number of columns of this matrix.
double[][]	getData()	Returns matrix entries as a two-dimensional array.
double[]	getDataRef()	Gets a reference to the underlying data array.
double	getEntry(int row, int column)	Get the entry in the specified row and column.
int	getRowDimension()	Returns the number of rows of this matrix.
DiagonalMatrix	inverse()	Computes the inverse of this diagonal matrix.
DiagonalMatrix	inverse(double threshold)	Computes the inverse of this diagonal matrix.
boolean	isSingular(double threshold)	Returns whether this diagonal matrix is singular, i.e.
DiagonalMatrix	multiply(DiagonalMatrix m)	Returns the result of postmultiplying this by m.
RealMatrix	multiply(RealMatrix m)	Returns the result of postmultiplying this by m.
void	multiplyEntry(int row, int column, double factor)	Multiplies (in place) the specified entry of this matrix by the specified value.
double[]	operate(double[] v)	Returns the result of multiplying this by the vector v.
double[]	preMultiply(double[] v)	Returns the (row) vector result of premultiplying this by the vector v.
RealVector	preMultiply(RealVector v)	Returns the (row) vector result of premultiplying this by the vector v.
void	setEntry(int row, int column, double value)	Set the entry in the specified row and column.
DiagonalMatrix	subtract(DiagonalMatrix m)	Returns this minus m.

Methods inherited from class org.apache.commons.math4.linear.AbstractRealMatrix

add, copySubMatrix, copySubMatrix, equals, getColumn, getColumnMatrix, getColumnVector, getFrobeniusNorm, getNorm, getRow, getRowMatrix, getRowVector, getSubMatrix, getSubMatrix, getTrace, hashCode, isSquare, operate, power, preMultiply, scalarAdd, scalarMultiply, setColumn, setColumnMatrix, setColumnVector, setRow, setRowMatrix, setRowVector, setSubMatrix, subtract, toString, transpose, walkInColumnOrder, walkInColumnOrder, walkInColumnOrder, walkInColumnOrder, walkInOptimizedOrder, walkInOptimizedOrder, walkInOptimizedOrder, walkInOptimizedOrder, walkInRowOrder, walkInRowOrder, walkInRowOrder, walkInRowOrder

Methods inherited from class org.apache.commons.math4.linear.RealLinearOperator

isTransposable, operateTranspose

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Details

DiagonalMatrix

public DiagonalMatrix(int dimension) throws NotStrictlyPositiveException

Creates a matrix with the supplied dimension.

Parameters:

dimension - Number of rows and columns in the new matrix.

Throws:

NotStrictlyPositiveException - if the dimension is not positive.

DiagonalMatrix

public DiagonalMatrix(double[] d)

Creates a matrix using the input array as the underlying data.
The input array is copied, not referenced.

Parameters:

d - Data for the new matrix.

DiagonalMatrix

public DiagonalMatrix(double[] d, boolean copyArray) throws NullArgumentException

Creates a matrix using the input array as the underlying data.
If an array is created specially in order to be embedded in a this instance and not used directly, the copyArray may be set to false. This will prevent the copying and improve performance as no new array will be built and no data will be copied.

Parameters:

d - Data for new matrix.

copyArray - if true, the input array will be copied, otherwise it will be referenced.

Throws:

NullArgumentException - if d is null

Method Details

createMatrix

public RealMatrix createMatrix(int rowDimension, int columnDimension) throws NotStrictlyPositiveException, DimensionMismatchException

Create a new RealMatrix of the same type as the instance with the supplied row and column dimensions.

Specified by:

createMatrix in interface RealMatrix

Specified by:

createMatrix in class AbstractRealMatrix

Parameters:

rowDimension - the number of rows in the new matrix

columnDimension - the number of columns in the new matrix

Returns:

a new matrix of the same type as the instance

Throws:

DimensionMismatchException - if the requested dimensions are not equal.

NotStrictlyPositiveException - if row or column dimension is not positive.

copy

public RealMatrix copy()

Returns a (deep) copy of this.

Specified by:

copy in interface RealMatrix

Specified by:

copy in class AbstractRealMatrix

Returns:

matrix copy

add

public DiagonalMatrix add(DiagonalMatrix m) throws MatrixDimensionMismatchException

Compute the sum of this and m.

Parameters:

m - Matrix to be added.

Returns:

this + m.

Throws:

MatrixDimensionMismatchException - if m is not the same size as this.

subtract

public DiagonalMatrix subtract(DiagonalMatrix m) throws MatrixDimensionMismatchException

Returns this minus m.

Parameters:

m - Matrix to be subtracted.

Returns:

this - m

Throws:

MatrixDimensionMismatchException - if m is not the same size as this.

multiply

public DiagonalMatrix multiply(DiagonalMatrix m) throws DimensionMismatchException

Returns the result of postmultiplying this by m.

Parameters:

m - matrix to postmultiply by

Returns:

this * m

Throws:

DimensionMismatchException - if columnDimension(this) != rowDimension(m)

multiply

public RealMatrix multiply(RealMatrix m) throws DimensionMismatchException

Returns the result of postmultiplying this by m.

Specified by:

multiply in interface RealMatrix

Overrides:

multiply in class AbstractRealMatrix

Parameters:

m - matrix to postmultiply by

Returns:

this * m

Throws:

DimensionMismatchException - if columnDimension(this) != rowDimension(m)

getData

public double[][] getData()

Returns matrix entries as a two-dimensional array.

Specified by:

getData in interface RealMatrix

Overrides:

getData in class AbstractRealMatrix

Returns:

2-dimensional array of entries

getDataRef

public double[] getDataRef()

Gets a reference to the underlying data array.

Returns:

1-dimensional array of entries.

getEntry

public double getEntry(int row, int column) throws OutOfRangeException

Get the entry in the specified row and column. Row and column indices start at 0.

Specified by:

getEntry in interface RealMatrix

Specified by:

getEntry in class AbstractRealMatrix

Parameters:

row - Row index of entry to be fetched.

column - Column index of entry to be fetched.

Returns:

the matrix entry at (row, column).

Throws:

OutOfRangeException - if the row or column index is not valid.

setEntry

public void setEntry(int row, int column, double value) throws OutOfRangeException, NumberIsTooLargeException

Set the entry in the specified row and column. Row and column indices start at 0.

Specified by:

setEntry in interface RealMatrix

Specified by:

setEntry in class AbstractRealMatrix

Parameters:

row - Row index of entry to be set.

column - Column index of entry to be set.

value - the new value of the entry.

Throws:

NumberIsTooLargeException - if row != column and value is non-zero.

OutOfRangeException - if the row or column index is not valid

addToEntry

public void addToEntry(int row, int column, double increment) throws OutOfRangeException, NumberIsTooLargeException

Adds (in place) the specified value to the specified entry of this matrix. Row and column indices start at 0.

Specified by:

addToEntry in interface RealMatrix

Overrides:

addToEntry in class AbstractRealMatrix

Parameters:

row - Row index of the entry to be modified.

column - Column index of the entry to be modified.

increment - value to add to the matrix entry.

Throws:

NumberIsTooLargeException - if row != column and increment is non-zero.

OutOfRangeException - if the row or column index is not valid.

multiplyEntry

public void multiplyEntry(int row, int column, double factor) throws OutOfRangeException

Multiplies (in place) the specified entry of this matrix by the specified value. Row and column indices start at 0.

Specified by:

multiplyEntry in interface RealMatrix

Overrides:

multiplyEntry in class AbstractRealMatrix

Parameters:

row - Row index of the entry to be modified.

column - Column index of the entry to be modified.

factor - Multiplication factor for the matrix entry.

Throws:

OutOfRangeException - if the row or column index is not valid.

getRowDimension

public int getRowDimension()

Returns the number of rows of this matrix.

Specified by:

getRowDimension in interface AnyMatrix

Specified by:

getRowDimension in class AbstractRealMatrix

Returns:

the number of rows.

getColumnDimension

public int getColumnDimension()

Returns the number of columns of this matrix.

Specified by:

getColumnDimension in interface AnyMatrix

Specified by:

getColumnDimension in class AbstractRealMatrix

Returns:

the number of columns.

operate

public double[] operate(double[] v) throws DimensionMismatchException

Returns the result of multiplying this by the vector v.

Specified by:

operate in interface RealMatrix

Overrides:

operate in class AbstractRealMatrix

Parameters:

v - the vector to operate on

Returns:

this * v

Throws:

DimensionMismatchException - if the length of v does not match the column dimension of this.

preMultiply

public double[] preMultiply(double[] v) throws DimensionMismatchException

Returns the (row) vector result of premultiplying this by the vector v.

Specified by:

preMultiply in interface RealMatrix

Overrides:

preMultiply in class AbstractRealMatrix

Parameters:

v - the row vector to premultiply by

Returns:

v * this

Throws:

DimensionMismatchException - if the length of v does not match the row dimension of this.

preMultiply

public RealVector preMultiply(RealVector v) throws DimensionMismatchException

Returns the (row) vector result of premultiplying this by the vector v.

Specified by:

preMultiply in interface RealMatrix

Overrides:

preMultiply in class AbstractRealMatrix

Parameters:

v - the row vector to premultiply by

Returns:

v * this

Throws:

DimensionMismatchException - if the dimension of v does not match the row dimension of this.

inverse

public DiagonalMatrix inverse() throws SingularMatrixException

Computes the inverse of this diagonal matrix.

Note: this method will use a singularity threshold of 0, use inverse(double) if a different threshold is needed.

Returns:

the inverse of m

Throws:

SingularMatrixException - if the matrix is singular

Since:

3.3

inverse

public DiagonalMatrix inverse(double threshold) throws SingularMatrixException

Computes the inverse of this diagonal matrix.

Parameters:

threshold - Singularity threshold.

Returns:

the inverse of m

Throws:

SingularMatrixException - if the matrix is singular

Since:

3.3

isSingular

public boolean isSingular(double threshold)

Returns whether this diagonal matrix is singular, i.e. any diagonal entry is equal to 0 within the given threshold.

Parameters:

threshold - Singularity threshold.

Returns:

true if the matrix is singular, false otherwise

Since:

3.3