cusp::dia_matrix< IndexType, ValueType, MemorySpace > Class Template Reference

Detailed description

template<typename IndexType, typename ValueType, class MemorySpace>
class cusp::dia_matrix< IndexType, ValueType, MemorySpace >

Diagonal (DIA) representation a sparse matrix.

Template Parameters

IndexType	Type used for matrix indices (e.g. int).
ValueType	Type used for matrix values (e.g. float).
MemorySpace	A memory space (e.g. cusp::host_memory or cusp::device_memory)

Overview

A dia_matrix is a sparse matrix container that stores each nonzero in a dense array2d container according to the diagonal each nonzero resides, the diagonal index of an ( i , j ) entry is | i - j |. This storage format is applicable to small set of matrices with significant structure. Storing the underlying entries in a array2d container avoids additional overhead associated with row or column indices but requires the storage of invalid entries associated with incomplete diagonals.

Note

The diagonal offsets should not contain duplicate entries.

Example

The following code snippet demonstrates how to create a 4-by-3 dia_matrix on the host with 3 diagonals (6 total nonzeros) and then copies the matrix to the device.

// include dia_matrix header file
#include <cusp/dia_matrix.h>
#include <cusp/print.h>

int main()
{
 // allocate storage for (4,3) matrix with 6 nonzeros in 3 diagonals
 cusp::dia_matrix<int,float,cusp::host_memory> A(4,3,6,3);

 // initialize diagonal offsets
 A.diagonal_offsets[0] = -2;
 A.diagonal_offsets[1] =  0;
 A.diagonal_offsets[2] =  1;

 // initialize diagonal values

 // first diagonal
 A.values(0,2) =  0;  // outside matrix
 A.values(1,2) =  0;  // outside matrix
 A.values(2,0) = 40;
 A.values(3,0) = 60;

 // second diagonal
 A.values(0,1) = 10;
 A.values(1,1) =  0;
 A.values(2,1) = 50;
 A.values(3,1) = 50;  // outside matrix

 // third diagonal
 A.values(0,2) = 20;
 A.values(1,2) = 30;
 A.values(2,2) =  0;  // outside matrix
 A.values(3,2) =  0;  // outside matrix

 // A now represents the following matrix
 //    [10 20  0]
 //    [ 0  0 30]
 //    [40  0 50]
 //    [ 0 60  0]

 // copy to the device
 cusp::dia_matrix<int,float,cusp::device_memory> B = A;

 // print the constructed dia_matrix
 cusp::print(B);
}

Examples:

dia.cu.

Definition at line 119 of file dia_matrix.h.

#include <dia_matrix.h>

Inheritance diagram for cusp::dia_matrix< IndexType, ValueType, MemorySpace >:

Public Methods
	dia_matrix (void)
	dia_matrix (const size_t num_rows, const size_t num_cols, const size_t num_entries, const size_t num_diagonals, const size_t alignment=32)
template<typename MatrixType >
	dia_matrix (const MatrixType &matrix)
void	resize (const size_t num_rows, const size_t num_cols, const size_t num_entries, const size_t num_diagonals)
void	resize (const size_t num_rows, const size_t num_cols, const size_t num_entries, const size_t num_diagonals, const size_t alignment)
void	swap (dia_matrix &matrix)
template<typename MatrixType >
dia_matrix &	operator= (const MatrixType &matrix)

Public Members
diagonal_offsets_array_type	diagonal_offsets
values_array_type	values

Constructor & Destructor Documentation

template<typename IndexType, typename ValueType, class MemorySpace>

cusp::dia_matrix< IndexType, ValueType, MemorySpace >::dia_matrix ( void  )

inline

Construct an empty dia_matrix_view.

Definition at line 165 of file dia_matrix.h.

template<typename IndexType, typename ValueType, class MemorySpace>

cusp::dia_matrix< IndexType, ValueType, MemorySpace >::dia_matrix	(	const size_t	num_rows,
		const size_t	num_cols,
		const size_t	num_entries,
		const size_t	num_diagonals,
		const size_t	alignment = 32
	)

Construct a dia_matrix with a specific shape, number of nonzero entries, and number of occupied diagonals.

Parameters

num_rows	Number of rows.
num_cols	Number of columns.
num_entries	Number of nonzero matrix entries.
num_diagonals	Number of occupied diagonals.
alignment	Amount of padding used to align the data structure (default 32).

template<typename IndexType, typename ValueType, class MemorySpace>

template<typename MatrixType >

cusp::dia_matrix< IndexType, ValueType, MemorySpace >::dia_matrix

(

const MatrixType &

matrix

)

Construct a dia_matrix from another matrix.

Parameters

matrix

Another sparse or dense matrix.

Member Function Documentation

template<typename IndexType, typename ValueType, class MemorySpace>

template<typename MatrixType >

dia_matrix& cusp::dia_matrix< IndexType, ValueType, MemorySpace >::operator=

(

const MatrixType &

matrix

)

Assignment from another matrix.

Parameters

matrix

Another sparse or dense matrix.

template<typename IndexType, typename ValueType, class MemorySpace>

void cusp::dia_matrix< IndexType, ValueType, MemorySpace >::resize	(	const size_t	num_rows,
		const size_t	num_cols,
		const size_t	num_entries,
		const size_t	num_diagonals
	)

Resize matrix dimensions and underlying storage

Parameters

num_rows	Number of rows.
num_cols	Number of columns.
num_entries	Number of nonzero matrix entries.
num_diagonals	Number of occupied diagonals.

template<typename IndexType, typename ValueType, class MemorySpace>

void cusp::dia_matrix< IndexType, ValueType, MemorySpace >::resize	(	const size_t	num_rows,
		const size_t	num_cols,
		const size_t	num_entries,
		const size_t	num_diagonals,
		const size_t	alignment
	)

Resize matrix dimensions and underlying storage

Parameters

num_rows	Number of rows.
num_cols	Number of columns.
num_entries	Number of nonzero matrix entries.
num_diagonals	Number of occupied diagonals.
alignment	Amount of padding used to align the data structure (default 32).

template<typename IndexType, typename ValueType, class MemorySpace>

void cusp::dia_matrix< IndexType, ValueType, MemorySpace >::swap

(

dia_matrix< IndexType, ValueType, MemorySpace > &

matrix

)

Swap the contents of two dia_matrix objects.

Parameters

matrix

Another dia_matrix with the same IndexType and ValueType.

Member Data Documentation

template<typename IndexType, typename ValueType, class MemorySpace>

diagonal_offsets_array_type cusp::dia_matrix< IndexType, ValueType, MemorySpace >::diagonal_offsets

Storage for the diagonal offsets.

Definition at line 156 of file dia_matrix.h.

template<typename IndexType, typename ValueType, class MemorySpace>

values_array_type cusp::dia_matrix< IndexType, ValueType, MemorySpace >::values

Storage for the nonzero entries of the DIA data structure.

Definition at line 160 of file dia_matrix.h.