gemm

Prototype

There are two prototypes of gemm available, please see below.

gemm( const Scalar >, const MatrixA& a, const MatrixB& b,
        const Scalar >, MatrixC& c );

gemm( const Scalar alpha, const MatrixA& a, const MatrixB& b,
        const Scalar beta, MatrixC& c );

Description

gemm (short for generic matrix-matrix operation) provides a C++ interface to BLAS routines SGEMM, DGEMM, CGEMM, and ZGEMM. gemm performs one of the matrix-matrix operations

C := alpha*op( A )*op( B ) + beta*C,

where op( X ) is one of

op( X ) = X or op( X ) = X' or op( X ) = conjg( X' ),

alpha and beta are scalars, and A, B and C are matrices, with op( A ) an m by k matrix, op( B ) a k by n matrix and C an m by n matrix.

The selection of the BLAS routine is done during compile-time, and is determined by the type of values contained in type MatrixA. The type of values is obtained through the value_type meta-function typename value_type<MatrixA>::type. Table X below illustrates to which specific routine this dispatching will take place.

Table 1.82. Dispatching of gemm.

Value type of MatrixA	BLAS routine	CBLAS routine	CUBLAS routine
`float`	SGEMM	cblas_sgemm	cublasSgemm
`double`	DGEMM	cblas_dgemm	cublasDgemm
`complex<float>`	CGEMM	cblas_cgemm	cublasCgemm
`complex<double>`	ZGEMM	cblas_zgemm	cublasZgemm

The original routines SGEMM, DGEMM, CGEMM, and ZGEMM have thirteen arguments, whereas gemm requires five arguments.

Table 1.83. Deduction of arguments of gemm.

Definition

Defined in header boost/numeric/bindings/blas/level3/gemm.hpp.

Parameters or Requirements on Types

Parameters

MatrixA

The definition of term 1

MatrixB

The definition of term 2

MatrixC

The definition of term 3.

Definitions may contain paragraphs.

Complexity

Example

#include <boost/numeric/bindings/blas/level3/gemm.hpp>
using namespace boost::numeric::bindings;

blas::gemm( x, y, z );

this will output

[5] 0 1 2 3 4 5