...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::average<Left, Right, std_valarray_tag, RightTag>
// In header: <boost/accumulators/numeric/functional/valarray.hpp> template<typename Left, typename Right, typename RightTag> struct average<Left, Right, std_valarray_tag, RightTag> { };