Matrix Package for Java

This package implements the matrix mathematical structure for Java.

Matrix Class

Fields

The following fields are used in the Matrix.java class.

Type	Name	Description
double[][]	matrix	The underlying data structure used to represent the matrix structure.
int	rows	The number of rows of the matrix.
int	columns	The number of columns of the matrix.
int	rank	The rank of the matrix.

Constructors

The following constructors can be used to instantiate the matrix object.

Constructor	Description
Matrix()	This default non-arg constructor, instantiates a 3x3 zero matrix.
Matrix(int rows, int columns)	This constructor creates a rows x columns zero matrix.
Matrix(int rows, int columns, MatrixType type)	This constructor creates a rows x columns preset matrix determined by the parameter type.
Matrix(double[][] array)	This constructor creates an array based on the parameter two-dimensional array.

Accessors/Mutators

The following methods can be used to access and modify certain fields of the matrix object.

Accessor/Mutator	Return	Description
getNumRows()	int	Returns the rows field.
getNumColumns()	int	Returns the columns field.
getRow(int index)	Matrix	Returns the row of a matrix at the given index.
getColumn(int index)	Matrix	Returns the column of the matrix at the given index.
getElement(int row, int column)	double	Returns the element at the given parameter index.
setElement(int row, int column, int value)	void	Sets the element at the parameter index to the new parameter value.
getRank()	int	Returns the rank field.

Methods

Below are the following methods that have been implemented in the Matrix.java class.

Method	Return	Description
toString()	String	This method returns a string representation of the matrix.
clone()	Matrix	This method returns a new matrix, which is a clone of the original matrix.
transpose()	Matrix	This method a new matrix, which is the transpose of the matrix.
multiply(double value)	void	This method multiplies the matrix with the scalar parameter value.
multiply(Matrix m)	Matrix	This method returns a new matrix, which is the product of the matrix and the parameter. The matrix is right multiplied by the parameter matrix m.
add(double value)	void	This method adds the scalar parameter value to every element of the matrix.
add(Matrix m)	void	This method adds the parameter matrix to the matrix.
power(int value)	Matrix	This method returns a new matrix, which is the result of the matrix to the power of the parameter value.
echelonForm(int end)	void	This method reduces the matrix to Reduced Row Echelon Form through the use of Gaussian Elimination.
join(Matrix m)	boolean	This method appends the parameter matrix to the end of the matrix.
submatrix(int[] indices)	Matrix	This method returns a submatrix of the matrix determined by the parameter.
inverse()	Matrix	This method returns the inverse of the matrix, if it exists.
solve(Matrix b)	Matrix	This method solves a system of linear equations in the form Ax = b, where A is the matrix, b is the parameter vector and x is the vector to solve. The return value is the vector x.
determinant()	Double	This method returns the determinant of the matrix, if it exists.

MatrixType Enum

Below are the following enums for the MatrixType.enum file.

Enums

Enum	Description
DEFAULT	nxm zero matrix.
IDENTITY	nxn identity matrix.
RANDOM	nxm matrix with random integers as elements.
ONE	nxm matrix with integer 1 for all elements.