Function builtin_signbit

extern/half/include/half.hpp:449–456

		/// \retval true if signbit set
		/// \retval false else
		template<typename T> bool builtin_signbit(T arg)
		{
		#if HALF_ENABLE_CPP11_CMATH
			return std::signbit(arg);
		#else
			return arg < T() || (arg == T() && T(1)/arg < T());
		#endif
		}

		/// \}
		/// \name Conversion