Boost LA

#include <boost/la/row.hpp> 
#include <boost/la/col.hpp> 
#include <boost/la/diag.hpp> 
#include <boost/la/vector_scalar_cast.hpp> 
#include <boost/la/vref.hpp>

namespace
boost
    {
    namespace
    la
        {
        //*** View proxies of vector type ***
        
        template <int R>
        -unspecified-return-type- row();        
        
        template <int C>
        -unspecified-return-type- col();        
        
        -unspecified-return-type- diag();        
        
        //Only enabled if: is_vector<A>::value
        template <class Scalar,class A>
        -unspecified-return_type- scalar_cast( A const & a );        
        
        //Only enabled if: is_vector<A>::value
        template <class A>
        -unspecified-return-type- vref( A & a );
        }
    }