Boost LA

#include <boost/la/vec_traits.hpp>

#include <boost/la/vec.hpp>

namespace
boost
    {
    namespace
    la
        {
        template <class Vector>
        struct vector_traits;
        
        template <class T,int Dim>
        struct
        vector_traits< vec<T,Dim> >
            {
            typedef T scalar_type;
            static int const dim=Dim;
        
            template <int I>
            static
            scalar_type
            r( vec<T,Dim> const & x )
                {
                return x.a[I];
                }
        
            template <int I>
            static
            scalar_type &
            w( vec<T,Dim> & x )
                {
                return x.a[I];
                }
        
            static
            scalar_type
            ir( int i, vec<T,Dim> const & x )
                {
                return x.a[i];
                }
        
            static
            scalar_type &
            iw( int i, vec<T,Dim> & x )
                {
                return x.a[i];
                }
            };
        }
    }