ru.sscc.matrix
Class DenseMatrix

java.lang.Object
  |
  +--ru.sscc.matrix.RealMatrix
        |
        +--ru.sscc.matrix.DenseMatrix

public class DenseMatrix

extends RealMatrix

An implementation of a rectangular dense matrix. In simple case the matrix is stored in the container "by rows", e.g. (i,j)th entry of the matrix is mapped to the (i*nColumns+j)-th entry of the matrix container. The "by columns" ordering is also possible. In common case, the position of (i,j)th entry in the underlying container is calculated by the formula startIndex + i*rowStep + j*columnStep

Common operations upon the matrix are implemented: matrix-by-vector multiplication, transposition, matrix assignment, and creation of a submatrix. A transposed matrix and submatrix share their bodies with the parent matrix.

See Also:

Serialized Form

Field Summary

int	columnStep The distance between two neighbour entries of the same row.
int	rowStep The distance between two neighbour entries of the same column.
int	startIndex The index of the first matrix entry in the container.

Fields inherited from class ru.sscc.matrix.RealMatrix

entries, nColumns, nRows

Constructor Summary

	DenseMatrix(int nRows, int nColumns) Constructs an instance with a clear double[] type matrix container and the "by rows" ordering.
	DenseMatrix(int nRows, int nColumns, boolean byRows) Constructs an instance with a clear double[] type matrix container with selection of "by rows" or "by columns" ordering.
	DenseMatrix(RealContainer entries, int nRows, int nColumns) Constructs an instance based on a user's real data container and ordered "by rows".
	DenseMatrix(RealContainer entries, int nRows, int nColumns, boolean byRows) Constructs an instance based on a user's real data container with selection of "by rows" or "by columns" ordering.
protected	DenseMatrix(RealContainer entries, int nRows, int nColumns, int startIndex, int rowStep, int columnStep) Constructs an instance based on a submatrix of a user's real data container.
	DenseMatrix(RealMatrix matrix) Constructs "by rows" ordered instance as a copy of a real matrix.
	DenseMatrix(RealMatrix matrix, boolean byRows) Constructs an instance as a copy of a real matrix with selection of "by rows" or "by columns" ordering.

Method Summary

double	add(int i, int j, double value) Adds the value of a matrix entry at the position (i,j).
void	assign(DenseMatrix matrix) Assignment: this = matrix (a dense matrix on the right).
void	assign(RealMatrix matrix) Assignment: this = matrix (an arbitrary real matrix on the right).
java.lang.Object	clone() Clones the matrix.
double	get(int i, int j) Gets a value of a matrix entry at the position (i,j).
RealVector	getColumn(int j) Returns the j-th column of the matrix (the vector is constructed upon the matrix container).
RealVector	getRow(int i) Returns the i-th row of the matrix (the vector is constructed upon the matrix container).
double	mul(int i, int j, double value) Multiplies a matrix entry at the position (i,j) by a value.
void	multiply(RealVector source, RealVector target) Multiplies the matrix by a column-vector.
void	multiplyAndAdd(double multiple, RealVector source, RealVector target) Calculates y += a * Ax, eg multiplies the matrix by a source column-vector, then multiplies the result by a real number and adds the result to the target vector.
void	multiplyAndAddT(double multiple, RealVector source, RealVector target) Calculates y += a * ATx, eg multiplies the transposed matrix by a source column-vector, then multiplies the result by a real number and adds the result to the target vector.
void	multiplyT(RealVector source, RealVector target) Multiplies the transposed matrix by a column-vector.
double	norm() Calculates the euclidean matrix norm (the square root of the sum of squared entries).
double	normMax() Calculates the matrix norm subordinated to the vector max-norm.
double	normSum() Calculates the matrix norm subordinated to the vector sum-norm.
protected int	pos(int i, int j) Returns the position of (i,j)th matrix entry in the container.
void	reuse() Allows to use the matrix in algebraic operations.
double	set(int i, int j, double value) Sets the value of a matrix entry at the position (i,j).
DenseMatrix	submatrix(int i, int j, int nRows, int nColumns) Generates a submatrix that starts from (i,j)th position of the matrix.
DenseMatrix	submatrix(int i, int j, int nRows, int nColumns, int rowInc, int columnInc) Generates a submatrix that starts from (i,j)th position of the matrix and is stored in it with specified increments.
DenseMatrix	transpose() Generates the transposed matrix based on the same container.

Methods inherited from class ru.sscc.matrix.RealMatrix

columnsNumber, ensureAlgebraic, ensureDimensions, ensureDimensions, ensureSquareMatrix, getContainer, lock, multiplyNN, multiplyNT, multiplyTN, multiplyTT, relativeAccuracy, rowsNumber, unlock

Methods inherited from class java.lang.Object

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

Field Detail

startIndex

public final int startIndex

The index of the first matrix entry in the container.

rowStep

public final int rowStep

The distance between two neighbour entries of the same column.

columnStep

public final int columnStep

The distance between two neighbour entries of the same row.

Constructor Detail

DenseMatrix

public DenseMatrix(int nRows,
                   int nColumns)

Constructs an instance with a clear double[] type matrix container and the "by rows" ordering.

Parameters:

nRows - a number of matrix rows

nColumns - a number of matrix columns

DenseMatrix

public DenseMatrix(int nRows,
                   int nColumns,
                   boolean byRows)

Constructs an instance with a clear double[] type matrix container with selection of "by rows" or "by columns" ordering.

Parameters:

nRows - a number of matrix rows

nColumns - a number of matrix columns

byRows - equals true if "by rows" ordering is used

DenseMatrix

public DenseMatrix(RealMatrix matrix)

Constructs "by rows" ordered instance as a copy of a real matrix.

Parameters:

matrix - the real matrix to get a copy from

DenseMatrix

public DenseMatrix(RealMatrix matrix,
                   boolean byRows)

Constructs an instance as a copy of a real matrix with selection of "by rows" or "by columns" ordering.

Parameters:

matrix - the real matrix to get a copy from

DenseMatrix

public DenseMatrix(RealContainer entries,
                   int nRows,
                   int nColumns)

Constructs an instance based on a user's real data container and ordered "by rows".

Parameters:

entries - a container of matrix entries

nRows - a number of matrix rows

nColumns - a number of matrix columns

DenseMatrix

public DenseMatrix(RealContainer entries,
                   int nRows,
                   int nColumns,
                   boolean byRows)

Constructs an instance based on a user's real data container with selection of "by rows" or "by columns" ordering.

Parameters:

entries - a container of matrix entries

nRows - a number of matrix rows

nColumns - a number of matrix columns

byRows - equals true if "by rows" ordering is used

DenseMatrix

protected DenseMatrix(RealContainer entries,
                      int nRows,
                      int nColumns,
                      int startIndex,
                      int rowStep,
                      int columnStep)

Constructs an instance based on a submatrix of a user's real data container.

Parameters:

entries - a container of matrix entries

nRows - a number of matrix rows

nColumns - a number of matrix columns

startIndex - an index of the first matrix entry in the container

rowStep - an interrow distance

columnStep - an intercolumn distance

Method Detail

submatrix

public final DenseMatrix submatrix(int i,
                                   int j,
                                   int nRows,
                                   int nColumns)

Generates a submatrix that starts from (i,j)th position of the matrix.

Parameters:

i - the first row number

j - the first column number

nRows - a number of submatrix rows

nColumns - a number of submatrix columns

submatrix

public final DenseMatrix submatrix(int i,
                                   int j,
                                   int nRows,
                                   int nColumns,
                                   int rowInc,
                                   int columnInc)

Generates a submatrix that starts from (i,j)th position of the matrix and is stored in it with specified increments.

Parameters:

i - the first row number

j - the first column number

nRows - a number of submatrix rows

nColumns - a number of submatrix columns

rowInc - an increment between neighbour rows

columnInc - an increment between neighbour columns

transpose

public final DenseMatrix transpose()

Generates the transposed matrix based on the same container. Throws IllegalStateException if the matrix is nonalgebraic.

multiply

public void multiply(RealVector source,
                     RealVector target)

Multiplies the matrix by a column-vector. Throws IllegalStateException if the matrix is nonalgebraic.

Overrides:

multiply in class RealMatrix

Parameters:

source - a source vector to multiply

target - a target vector to write the result

multiplyT

public void multiplyT(RealVector source,
                      RealVector target)

Multiplies the transposed matrix by a column-vector. Throws IllegalStateException if the matrix is nonalgebraic.

Overrides:

multiplyT in class RealMatrix

Parameters:

source - a source vector to multiply

target - a target vector to write the result

multiplyAndAdd

public void multiplyAndAdd(double multiple,
                           RealVector source,
                           RealVector target)

Calculates y += a * Ax, eg multiplies the matrix by a source column-vector, then multiplies the result by a real number and adds the result to the target vector. Throws IllegalStateException if the matrix is nonalgebraic.

Parameters:

multiple - a multiple

source - a source vector to multiply

target - a target vector to add the result

multiplyAndAddT

public void multiplyAndAddT(double multiple,
                            RealVector source,
                            RealVector target)

Calculates y += a * A^Tx, eg multiplies the transposed matrix by a source column-vector, then multiplies the result by a real number and adds the result to the target vector. Throws IllegalStateException if the matrix is nonalgebraic.

Parameters:

multiple - a multiple

source - a source vector to multiply

target - a target vector to add the result

getRow

public final RealVector getRow(int i)

Returns the i-th row of the matrix (the vector is constructed upon the matrix container).

getColumn

public final RealVector getColumn(int j)

Returns the j-th column of the matrix (the vector is constructed upon the matrix container).

get

public double get(int i,
                  int j)

Gets a value of a matrix entry at the position (i,j).

Overrides:

get in class RealMatrix

Parameters:

i - a zero based row number

j - a zero based column number

Returns:

an entry value at the required position

set

public double set(int i,
                  int j,
                  double value)

Sets the value of a matrix entry at the position (i,j).

Overrides:

set in class RealMatrix

Parameters:

i - a zero based row number

j - a zero based column number

value - a value to set

Returns:

the set value

add

public double add(int i,
                  int j,
                  double value)

Adds the value of a matrix entry at the position (i,j).

Overrides:

add in class RealMatrix

Parameters:

i - a zero based row number

j - a zero based column number

value - a value to set

Returns:

the addition result

mul

public double mul(int i,
                  int j,
                  double value)

Multiplies a matrix entry at the position (i,j) by a value.

Overrides:

mul in class RealMatrix

Parameters:

i - a zero based row number

j - a zero based column number

value - a value to set

Returns:

the multiplication result

reuse

public final void reuse()

Allows to use the matrix in algebraic operations.

pos

protected final int pos(int i,
                        int j)

Returns the position of (i,j)th matrix entry in the container.

clone

public java.lang.Object clone()

Clones the matrix. If the cloned matrix is a submatrix of a dense metrix, the cloned matrix will contain the submatrix entries only.

Overrides:

clone in class RealMatrix

assign

public void assign(RealMatrix matrix)

Assignment: this = matrix (an arbitrary real matrix on the right).

Parameters:

matrix - the matrix to get copy from

Throws:

java.lang.IllegalStateException - is thrown if this matrix isn't algebraic

java.lang.IllegalArgumentException - is thrown if the dimensions of matrices are incompatible

assign

public void assign(DenseMatrix matrix)

Assignment: this = matrix (a dense matrix on the right).

Parameters:

matrix - the matrix to get copy from

Throws:

java.lang.IllegalStateException - is thrown if this matrix isn't algebraic

java.lang.IllegalArgumentException - is thrown if the dimensions of matrices are incompatible

norm

public double norm()

Calculates the euclidean matrix norm (the square root of the sum of squared entries).

normMax

public double normMax()

Calculates the matrix norm subordinated to the vector max-norm.

normSum

public double normSum()

Calculates the matrix norm subordinated to the vector sum-norm.