add sprout::exp2, expm1

sprout/math/expm1.hpp

@@ -0,0 +1,45 @@
+#ifndef SPROUT_MATH_EXPM1_HPP
+#define SPROUT_MATH_EXPM1_HPP
+
+#include <type_traits>
+#include <sprout/config.hpp>
+#include <sprout/math/exp.hpp>
+#include <sprout/math/constants.hpp>
+#include <sprout/utility/enabler_if.hpp>
+#if SPROUT_USE_BUILTIN_CMATH_FUNCTION
+#	include <cmath>
+#endif
+
+namespace sprout {
+	namespace math {
+		namespace detail {
+			template<
+				typename FloatType,
+				typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
+			>
+			inline SPROUT_CONSTEXPR FloatType
+			expm1(FloatType x) {
+				return sprout::math::detail::exp(x) - 1;
+			}
+
+			template<
+				typename IntType,
+				typename sprout::enabler_if<std::is_integral<IntType>::value>::type = sprout::enabler
+			>
+			inline SPROUT_CONSTEXPR double
+			expm1(IntType x) {
+				return sprout::math::detail::expm1(static_cast<double>(x));
+			}
+		}	// namespace detail
+
+#	if SPROUT_USE_BUILTIN_CMATH_FUNCTION
+		using std::expm1;
+#	else
+		using sprout::math::detail::expm1;
+#	endif
+	}	// namespace math
+
+	using sprout::math::expm1;
+}	// namespace sprout
+
+#endif	// #ifndef SPROUT_MATH_EXPM1_HPP