edu.northwestern.at.utils.math.matrix
Class SparseMatrix

java.lang.Object
  edu.northwestern.at.utils.math.matrix.AbstractMatrix
      edu.northwestern.at.utils.math.matrix.SparseMatrix

All Implemented Interfaces:

Matrix, java.io.Serializable

public class SparseMatrix
extends AbstractMatrix
implements Matrix

Implements a sparse matrix using a hash map.

See Also:

Serialized Form

Field Summary

protected java.util.HashMap

matrixData The matrix contents as a two-dimensional array of doubles.

Fields inherited from class edu.northwestern.at.utils.math.matrix.AbstractMatrix

columns, rows

Constructor Summary

protected	SparseMatrix() Don't allow instantiation without size specification.
	SparseMatrix(int rows, int columns) Create a matrix of the specified size.

Method Summary

double	get(int row, int column) Gets value of element at given row and column.
int	getUsed()
void	set(int row, int column, double value) Set an element at the given position to a new value.

Methods inherited from class edu.northwestern.at.utils.math.matrix.AbstractMatrix

columns, get, getColumn, getColumnData, getColumns, getColumns, getCopy, getRow, getRowData, getRows, getRows, getSubMatrix, getSubMatrix, getSubMatrix, getSubMatrix, rows, set, set, setColumn, setColumnData, setColumnData, setRow, setRowData, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface edu.northwestern.at.utils.math.matrix.Matrix

columns, get, getColumn, getColumnData, getColumns, getColumns, getCopy, getRow, getRowData, getRows, getRows, getSubMatrix, getSubMatrix, getSubMatrix, getSubMatrix, rows, set, set, setColumn, setColumnData, setColumnData, setRow, setRowData, toString

Field Detail

matrixData

protected java.util.HashMap matrixData

The matrix contents as a two-dimensional array of doubles.

Constructor Detail

SparseMatrix

protected SparseMatrix()

Don't allow instantiation without size specification.

SparseMatrix

public SparseMatrix(int rows,
                    int columns)

Create a matrix of the specified size.

Parameters:

rows - Number of rows.

columns - Number of columns.

Each element of the result matrix will be set to zero.

Method Detail

set

public void set(int row,
                int column,
                double value)

Set an element at the given position to a new value.

Specified by:

set in interface Matrix

Specified by:

set in class AbstractMatrix

Parameters:

row - Row in which the element occurs.

column - Column in which the element occurs.

value - The new value to be set.

Note: only non-zero values are stored.

get

public double get(int row,
                  int column)

Gets value of element at given row and column.

Specified by:

get in interface Matrix

Specified by:

get in class AbstractMatrix

Parameters:

row - Row in which the element occurs.

column - Column in which the element occurs.

Returns:

The value at the given position.

getUsed

public int getUsed()