template<class T>
valarray<T> operator*(const valarray<T>& lhs,
const valarray<T>& rhs);
template<class T>
valarray<T> operator*(const valarray<T> lhs, const T& rhs);
template<class T>
valarray<T> operator*(const T& lhs, const valarray<T>& rhs);
The first template operator returns an object of class valarray<T>, each of whose elements I is x[I] * y[I]. The
second template operator stores in element I x[I] * y. The third template operator stores in element I x * y[I].