Method tgamma

extern/half/include/half.hpp:1616–1635

Gamma implementation. \param arg function argument \return function value stored in single-preicision

			/// \param arg function argument
			/// \return function value stored in single-preicision
			static expr tgamma(float arg)
			{
			#if HALF_ENABLE_CPP11_CMATH
				return expr(std::tgamma(arg));
			#else
				if(arg == 0.0f)
					return builtin_signbit(arg) ? expr(-std::numeric_limits<float>::infinity()) : expr(std::numeric_limits<float>::infinity());
				if(arg < 0.0f)
				{
					float i, f = std::modf(-arg, &i);
					if(f == 0.0f)
						return expr(std::numeric_limits<float>::quiet_NaN());
					double value = 3.1415926535897932384626433832795 / (std::sin(3.1415926535897932384626433832795*f)*std::exp(lgamma(1.0-arg)));
					return expr(static_cast<float>((std::fmod(i, 2.0f)==0.0f) ? -value : value));
				}
				if(builtin_isinf(arg))
					return expr(arg);
				return expr(static_cast<float>(std::exp(lgamma(static_cast<double>(arg)))));
			#endif
			}

			/// Floor implementation.
			/// \param arg value to round