Morpheus::Matrix Class Reference

Stores a dense matrix. More...

#include <Morpheus_Matrix.h>

Public Member Functions
Constructors and destructors

	Matrix (const int nrows, const int ncols)
	Constructor.
	~Matrix ()
	Destructor.
Accessor functions

double &	operator() (const int row, const int col)
	Accesses a single entry of the matrix.
int	getNumRows () const
	Returns the number of rows.
int	getNumCols () const
	Returns the number of columns.
int	getNumEntries () const
	Returns the number of entries.
Multiplication routines

void	multiply (const Vector &X, Vector &Y) const
	Computes a matrix-vector multiplication.
void	multiply (const Matrix &X, Matrix &Y) const
	Computes a matrix-matrix multiplication.
Matrix property query methods

bool	isSymmetric () const
	Determines whether the matrix is symmetric.
bool	isUpperTriangular () const
	Determines whether the matrix is upper triangular.
bool	approxEqual (const Matrix &m, const double tol) const
	Determines whether this matrix is approximately equal to another matrix.
Norms

double	norm1 () const
	Maximum absolute column sum.
double	normInf () const
	Maximum absolute row sum.
I/O functions

void	print () const
	Prints matrix to console.
Private Attributes
int	nrows_
	Number of rows.
int	ncols_
	Number of columns.
double **	data_
	Pointer to raw data.

Detailed Description

Stores a dense matrix.

Todo:

Add a function for computing the Frobenius norm

Add a function for computing the 2-norm

Add a function for reading a matrix from a file

Examples:: Morpheus_Matrix_Tests.cpp.

Definition at line 25 of file Morpheus_Matrix.h.

Constructor & Destructor Documentation

Morpheus::Matrix::Matrix	(	const int	nrows,
		const int	ncols
	)

Constructor.

Allocates memory for a dense matrix. If either nrows or ncols is not positive, the program terminates.

Parameters:

`[in]`	nrows	Number of rows
`[in]`	ncols	Number of columns

Definition at line 15 of file Morpheus_Matrix.cpp.

Morpheus::Matrix::~Matrix ( )

Destructor.

Deallocates memory allocated in the constructor

Definition at line 31 of file Morpheus_Matrix.cpp.

Member Function Documentation

double & Morpheus::Matrix::operator()	(	const int	row,
		const int	col
	)

Accesses a single entry of the matrix.

Parameters:

`[in]`	row	Row
`[out]`	col	Column

Note:: This is 0-based, not 1-based indexing

Usage:

 Matrix m(4,3);
 m(0,0) = 1; m(0,1) = 0; m(0,2) = 0;
 m(1,0) = 0; m(1,1) = 1; m(1,2) = 0;
 m(2,0) = 0; m(2,1) = 0; m(2,2) = 1;
 m(3,0) = 0; m(3,1) = 0; m(3,2) = 0;

creates the matrix
$\left[\begin{array}{rrr} 1&0&0\\0&1&0\\0&0&1\\0&0&0 \end{array}\right]$

Definition at line 41 of file Morpheus_Matrix.cpp.

int Morpheus::Matrix::getNumRows ( ) const

Returns the number of rows.

Definition at line 159 of file Morpheus_Matrix.cpp.

int Morpheus::Matrix::getNumCols ( ) const

Returns the number of columns.

Definition at line 165 of file Morpheus_Matrix.cpp.

int Morpheus::Matrix::getNumEntries ( ) const

Returns the number of entries.

Definition at line 171 of file Morpheus_Matrix.cpp.

void Morpheus::Matrix::multiply	(	const Vector &	X,
		Vector &	Y
	)			const

Computes a matrix-vector multiplication.

Parameters:

`[in]`	X	vector to be multiplied
`[out]`	Y	result of multiplication

Note:: This function does not allocate memory for Y; it only fills in the values. The number of rows of the matrix must equal the number of entries in Y. The number of columns of the matrix must equal the number of entries in X. Otherwise, the program will terminate.

Todo:: Write a test for this function

Examples:: Morpheus_Matrix_Tests.cpp.

Definition at line 47 of file Morpheus_Matrix.cpp.

void Morpheus::Matrix::multiply	(	const Matrix &	X,
		Matrix &	Y
	)			const

Computes a matrix-matrix multiplication.

Parameters:

`[in]`	X	matrix to be multiplied
`[out]`	Y	result of multiplication

Note:: This function does not allocate memory for Y; it only fills in the values. The number of rows of the calling matrix must equal the number of rows of Y. The number of columns of the calling matrix must equal the number of rows of X. X and Y must have the same number of columns. Otherwise, the program will terminate.

Definition at line 64 of file Morpheus_Matrix.cpp.

bool Morpheus::Matrix::isSymmetric ( ) const

Determines whether the matrix is symmetric.

Note:: The symmetry is not stored as a property of the matrix. Every time this function is called, it will perform the O(n^2) comparison of entries.