Boost LA

vref

namespace
boost
    {
    namespace
    la
        {
        //Only enabled if: is_vector<A>::value
        template <class A>
        -unspecified-return-type- vref( A & a );
        }
    }

Returns:

An identity view proxy of a; that is, it simply accesses the elements of a.

This allows calling overloaded operators when a is of built-in type, for example a plain old C array.