Function builtin_isnan

include/half/half.hpp:420–429

		/// \retval true if not a number
		/// \retval false else
		template<typename T> bool builtin_isnan(T arg)
		{
		#if HALF_ENABLE_CPP11_CMATH
			return std::isnan(arg);
		#elif defined(_MSC_VER)
			return ::_isnan(static_cast<double>(arg)) != 0;
		#else
			return arg != arg;
		#endif
		}

		/// Check sign.
		/// \tparam T argument type (builtin floating point type)