// vector * T
template<int Dim, class T1, class T2> inline
typename boost::units::multiply_typeof_helper<T2, vector<Dim, T1> >::type
operator*(const vector<Dim, T1>&lhs, const T2& rhs)
{ return rhs * lhs; }
Since multiply_typeof_helper<T1,T2> is really just a glorified version of typeof(T1()*T2()), what you're saying here is that the return type of the product of a vector and a scalar is the return type of the product of a vector and a scalar. You need to define the top-level multiply operation; define it something like this :
// vector * T
template<int Dim, class T1, class T2> inline
vector<Dim,typename boost::units::multiply_typeof_helper<T2, T1 >::type>
operator*(const vector<Dim, T1>&lhs, const T2& rhs)
{ //return rhs * lhs; this return statement is also wrong, since it is recursive, defining the returned value in terms of the operator itself...}
Cheers,
Matthias