syr2

Prototype

There is one prototype of syr2 available, please see below.

syr2( const Scalar >, const VectorX& x, const VectorY& y, MatrixA& a );

Description

syr2 (short for symmetric rank-2 update) provides a C++ interface to BLAS routines SSYR2 and DSYR2. syr2 performs the symmetric rank 2 operation

A := alpha*x*y' + alpha*y*x' + A,

where alpha is a scalar, x and y are n element vectors and A is an n by n symmetric matrix.

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

Table 1.66. Dispatching of syr2.

Value type of VectorX	BLAS routine	CBLAS routine	CUBLAS routine
`float`	SSYR2	cblas_ssyr2	cublasSsyr2
`double`	DSYR2	cblas_dsyr2	Unavailable

The original routines SSYR2 and DSYR2 have nine arguments, whereas syr2 requires four arguments.

Table 1.67. Deduction of arguments of syr2.

Definition

Defined in header boost/numeric/bindings/blas/level2/syr2.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/level2/syr2.hpp>
using namespace boost::numeric::bindings;

blas::syr2( x, y, z );

this will output

[5] 0 1 2 3 4 5