There is one prototype of syr2
            available, please see below. 
syr2( const Scalar >, const VectorX& x, const VectorY& y, MatrixA& a );
            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 | 
|---|---|---|---|
| 
                       | SSYR2 | cblas_ssyr2 | cublasSsyr2 | 
| 
                       | DSYR2 | cblas_dsyr2 | Unavailable | 
            The original routines SSYR2 and DSYR2 have nine arguments, whereas syr2 requires four arguments.
          
            Defined in header boost/numeric/bindings/blas/level2/syr2.hpp.
          
Parameters
The definition of term 1
The definition of term 2
The definition of term 3.
Definitions may contain paragraphs.
#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