fix math functions

sprout/math/is_integer.hpp

@@ -0,0 +1,28 @@
+#ifndef SPROUT_MATH_IS_INTEGER_HPP
+#define SPROUT_MATH_IS_INTEGER_HPP
+
+#include <type_traits>
+#include <sprout/config.hpp>
+#include <sprout/type_traits/enabler_if.hpp>
+#include <sprout/math/trunc.hpp>
+
+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 bool
+			is_integer(FloatType x) {
+				return x == sprout::math::trunc(x);
+			}
+		}	// namespace detail
+
+		using sprout::math::detail::is_integer;
+	}	// namespace math
+
+	using sprout::math::is_integer;
+}	// namespace sprout
+
+#endif	// #ifndef SPROUT_MATH_IS_INTEGER_HPP