cusp::permutation_matrix< IndexType, MemorySpace > Class Template Reference

#include <permutation_matrix.h>

Inheritance diagram for cusp::permutation_matrix< IndexType, MemorySpace >:

Public Methods
	permutation_matrix (void)
	permutation_matrix (const size_t num_rows)
template<typename MemorySpace2 >
	permutation_matrix (const permutation_matrix< IndexType, MemorySpace2 > &matrix)
template<typename ArrayType >
	permutation_matrix (const size_t num_rows, const ArrayType &permutation)
void	resize (const size_t num_rows)
void	swap (permutation_matrix &matrix)
template<typename MatrixType >
void	symmetric_permute (MatrixType &matrix)

Public Members
permutation_array_type	permutation

Detailed description

template<typename IndexType, typename MemorySpace>
class cusp::permutation_matrix< IndexType, MemorySpace >

Simple representation a permutation matrix.

Template Parameters

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

Overview

This matrix represents a row permutation of the identity matrix.

Example

The following code snippet demonstrates how to create a 3-by-3 permutation_matrix on the host with 3 nonzeros and permutes a coo_matrix by first by row and then by column.

// include the permutation_matrix header file
#include <cusp/coo_matrix.h>
#include <cusp/multiply.h>
#include <cusp/permutation_matrix.h>
#include <cusp/print.h>
int main()
{
  typedef cusp::host_memory MemorySpace;
 
  // allocate storage for (3,3) matrix with 5 nonzeros
  cusp::coo_matrix<int,float,MemorySpace> A(3,3,7);
  // initialize matrix entries on host
  A.row_indices[0] = 0; A.column_indices[0] = 0; A.values[0] = 10;
  A.row_indices[1] = 0; A.column_indices[1] = 1; A.values[1] = 20;
  A.row_indices[2] = 0; A.column_indices[2] = 2; A.values[2] = 30;
  A.row_indices[3] = 1; A.column_indices[3] = 0; A.values[3] = 40;
  A.row_indices[4] = 1; A.column_indices[4] = 1; A.values[4] = 50;
  A.row_indices[5] = 2; A.column_indices[5] = 0; A.values[5] = 60;
  A.row_indices[6] = 2; A.column_indices[6] = 2; A.values[6] = 70;
  // A now represents the following matrix
  //    [10  0 20]
  //    [30 40  0]
  //    [ 0  0 50]
  // generate a index permutation that swaps row or column 0 and 2
  cusp::array1d<int,MemorySpace> permutation(3);
  permutation[0] = 2; // 0 maps to 2
  permutation[1] = 1; // 1 maps to 1
  permutation[2] = 0; // 2 maps to 0
  // allocate storage for (3,3) matrix with 3 nonzeros
  cusp::permutation_matrix<int,MemorySpace> P(3, permutation);
  // P now represents the following permutation matrix
  //    [0 0 1]
  //    [0 1 0]
  //    [1 0 0]
  // permute the rows of A
  cusp::coo_matrix<int,float,MemorySpace> PA;
  cusp::multiply(P, A, PA);
  // permute the column of PA
  cusp::coo_matrix<int,float,MemorySpace> PAP;
  cusp::multiply(PA, P, PAP);
  // print the matrix
  cusp::print(cusp::array2d<float,MemorySpace>(A));
  // print the permuted matrix
  cusp::print(cusp::array2d<float,MemorySpace>(PAP));
}

Definition at line 108 of file permutation_matrix.h.

Constructor & Destructor Documentation

permutation_matrix() [1/4]

template<typename IndexType , typename MemorySpace >

cusp::permutation_matrix< IndexType, MemorySpace >::permutation_matrix ( void  )

inline

Construct an empty permutation_matrix.

Definition at line 143 of file permutation_matrix.h.

permutation_matrix() [2/4]

template<typename IndexType , typename MemorySpace >

cusp::permutation_matrix< IndexType, MemorySpace >::permutation_matrix ( const size_t  num_rows )

inline

Construct a permutation_matrix with a specific number of rows.

Parameters

num_rows

Number of rows.

Definition at line 149 of file permutation_matrix.h.

permutation_matrix() [3/4]

template<typename IndexType , typename MemorySpace >

template<typename MemorySpace2 >

cusp::permutation_matrix< IndexType, MemorySpace >::permutation_matrix ( const permutation_matrix< IndexType, MemorySpace2 > &  matrix )

inline

Construct a permutation_matrix from another matrix.

Template Parameters

MemorySpace2

Memory space of the input matrix

Parameters

matrix

Another sparse or dense matrix.

Definition at line 160 of file permutation_matrix.h.

permutation_matrix() [4/4]

template<typename IndexType , typename MemorySpace >

template<typename ArrayType >

cusp::permutation_matrix< IndexType, MemorySpace >::permutation_matrix ( const size_t  num_rows, const ArrayType &  permutation  )

inline

Construct a permutation_matrix from another matrix.

Template Parameters

ArrayType

permutation array type

Parameters

num_rows	Number of rows.
permutation	Array containing the permutation indices.

Definition at line 171 of file permutation_matrix.h.

Member Function Documentation

resize()

template<typename IndexType , typename MemorySpace >

void cusp::permutation_matrix< IndexType, MemorySpace >::resize

(

const size_t

num_rows

)

Resize matrix dimensions and underlying storage

Parameters

num_rows

Number of rows.

swap()

template<typename IndexType , typename MemorySpace >

void cusp::permutation_matrix< IndexType, MemorySpace >::swap

(

permutation_matrix< IndexType, MemorySpace > &

matrix

)

Swap the contents of two permutation_matrix objects.

Parameters

matrix

Another permutation_matrix with the same IndexType.

symmetric_permute()

template<typename IndexType , typename MemorySpace >

template<typename MatrixType >

void cusp::permutation_matrix< IndexType, MemorySpace >::symmetric_permute

(

MatrixType &

matrix

)

Permute rows and columns of matrix elements

Template Parameters

MatrixType

Type of input matrix to permute

Parameters

matrix

Input matrix to apply symmetric permutation.

Member Data Documentation

permutation

template<typename IndexType , typename MemorySpace >

permutation_array_type cusp::permutation_matrix< IndexType, MemorySpace >::permutation

Storage for the permutation indices

Definition at line 139 of file permutation_matrix.h.