text: #ifndef SPROUT_MATH_COS_HPP
  #define SPROUT_MATH_COS_HPP
  
  #include <cstddef>
  #include <limits>
  #include <type_traits>
  #include <sprout/config.hpp>
  #include <sprout/math/detail/config.hpp>
  #include <sprout/math/factorial.hpp>
  #include <sprout/type_traits/enabler_if.hpp>
  
  namespace sprout {
  	namespace math {
  		namespace detail {
  			template<typename T>
  			inline SPROUT_CONSTEXPR T
  			cos_impl(T x, T tmp, std::size_t n, T x2n) {
  				return 2 * n > sprout::math::factorial_limit<T>() ? tmp
  					: sprout::math::detail::cos_impl(
  						x,
  						tmp + (n % 2 ? -1 : 1) * x2n / sprout::math::factorial<T>(2 * n),
  						n + 1,
  						x2n * x * x
  						)
  					;
  			}
  
  			template<
  				typename FloatType,
  				typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
  			>
  			inline SPROUT_CONSTEXPR FloatType
  			cos(FloatType x) {
  				typedef double type;
  				return x == std::numeric_limits<FloatType>::infinity()
  					|| x == -std::numeric_limits<FloatType>::infinity()
  					? std::numeric_limits<FloatType>::quiet_NaN()
  					: static_cast<FloatType>(sprout::math::detail::cos_impl(
  						static_cast<type>(x),
  						type(1),
  						1,
  						static_cast<type>(x) * static_cast<type>(x)
  						))
  					;
  			}
  
  			template<
  				typename IntType,
  				typename sprout::enabler_if<std::is_integral<IntType>::value>::type = sprout::enabler
  			>
  			inline SPROUT_CONSTEXPR double
  			cos(IntType x) {
  				return sprout::math::detail::cos(static_cast<double>(x));
  			}
  		}	// namespace detail
  
  		using NS_SPROUT_MATH_DETAIL::cos;
  	}	// namespace math
  
  	using sprout::math::cos;
  }	// namespace sprout
  
  #endif	// #ifndef SPROUT_MATH_COS_HPP
  