...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::unary_minus_base
// In header: <boost/accumulators/numeric/functional.hpp> template<typename Arg, typename EnableIf = void> struct unary_minus_base : public std::unary_function< Arg, typeof(-lvalue< Arg >())> { // public member functions result_type operator()(Arg &) const; };