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

#include <linear_operator.h>

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

Public Methods
	linear_operator (void)
	linear_operator (IndexType num_rows, IndexType num_cols)
	linear_operator (IndexType num_rows, IndexType num_cols, IndexType num_entries)

Detailed description

template<typename ValueType, typename MemorySpace, typename IndexType = int>
class cusp::linear_operator< ValueType, MemorySpace, IndexType >

Abstract representation of a linear operator.

Template Parameters

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

Overview

A linear operator is a abstract container that supports encapsulates abstract linear operators for use with other routines. All linear operators should provide a implementation of the operator()(x,y) for interoperability with the multiply routine.

Example

The following code snippet demonstrates how to create a custom linear operator.

// include linear_operator header file
#include <cusp/linear_operator.h>
 
#include <cusp/csr_matrix.h>
#include <cusp/multiply.h>
#include <cusp/print.h>
 
#include <cusp/gallery/poisson.h>
#include <cusp/precond/diagonal.h>
 
template <typename MatrixType>
struct Dinv_A : public cusp::linear_operator<typename MatrixType::value_type, typename MatrixType::memory_space>
{
  typedef typename MatrixType::value_type ValueType;
  typedef typename MatrixType::memory_space MemorySpace;
 
  const MatrixType& A;
  const cusp::precond::diagonal<ValueType,MemorySpace> Dinv;
 
  Dinv_A(const MatrixType& A)
      : A(A), Dinv(A),
        cusp::linear_operator<ValueType,MemorySpace>(A.num_rows, A.num_cols, A.num_entries + A.num_rows)
  {}
 
  template <typename Array1, typename Array2>
  void operator()(const Array1& x, Array2& y) const
  {
      cusp::multiply(A,x,y);
      cusp::multiply(Dinv,y,y);
  }
};
 
int main(void)
{
  typedef cusp::csr_matrix<int, float, cusp::device_memory> CsrMatrix;
 
  CsrMatrix A;
 
  // number of entries
  const int N = 4;
 
  // construct Poisson example matrix
  cusp::gallery::poisson5pt(A, N, N);
 
  // construct instance of custom operator perform D^{-1}A
  Dinv_A<CsrMatrix> M(A);
 
  // initialize x and y vectors
  cusp::array1d<float, cusp::device_memory> x(A.num_rows, 1);
  cusp::array1d<float, cusp::device_memory> y(A.num_rows, 0);
 
  // call operator()(x,y) through multiply interface
  cusp::multiply(M,x,y);
 
  // print the transformed vector
  cusp::print(y);
}

Definition at line 111 of file linear_operator.h.

Constructor & Destructor Documentation

linear_operator() [1/3]

template<typename ValueType , typename MemorySpace , typename IndexType = int>

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

inline

Construct an empty linear_operator.

Definition at line 121 of file linear_operator.h.

linear_operator() [2/3]

template<typename ValueType , typename MemorySpace , typename IndexType = int>

cusp::linear_operator< ValueType, MemorySpace, IndexType >::linear_operator ( IndexType  num_rows, IndexType  num_cols  )

inline

Construct a linear_operator with a specific shape.

Parameters

num_rows	Number of rows.
num_cols	Number of columns.

Definition at line 129 of file linear_operator.h.

linear_operator() [3/3]

template<typename ValueType , typename MemorySpace , typename IndexType = int>

cusp::linear_operator< ValueType, MemorySpace, IndexType >::linear_operator ( IndexType  num_rows, IndexType  num_cols, IndexType  num_entries  )

inline

Construct a linear_operator with a specific shape and number of nonzero entries.

Parameters

num_rows	Number of rows.
num_cols	Number of columns.
num_entries	Number of nonzero entries.

Definition at line 139 of file linear_operator.h.