...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
boost::numeric::functional::promote
// In header: <boost/accumulators/numeric/functional.hpp> template<typename To, typename From, typename ToTag, typename FromTag> struct promote : public boost::numeric::functional::promote_base< To, From, void > { };