From 6baf0822343fd9599f7a8c5a0f59c1a56c9f84cb Mon Sep 17 00:00:00 2001
From: bolero-MURAKAMI <bolero.murakami@gmail.com>
Date: Fri, 4 May 2012 18:02:42 +0900
Subject: [PATCH] add sprout::log10, log2, log1p

---
 sprout/math/constants.hpp   | 28 +++++++++++++++++++++++
 sprout/math/exponential.hpp |  3 +++
 sprout/math/log.hpp         |  3 ++-
 sprout/math/log10.hpp       | 45 +++++++++++++++++++++++++++++++++++++
 sprout/math/log1p.hpp       | 44 ++++++++++++++++++++++++++++++++++++
 sprout/math/log2.hpp        | 45 +++++++++++++++++++++++++++++++++++++
 6 files changed, 167 insertions(+), 1 deletion(-)
 create mode 100644 sprout/math/log10.hpp
 create mode 100644 sprout/math/log1p.hpp
 create mode 100644 sprout/math/log2.hpp

diff --git a/sprout/math/constants.hpp b/sprout/math/constants.hpp
index da7de011..64a9298b 100644
--- a/sprout/math/constants.hpp
+++ b/sprout/math/constants.hpp
@@ -26,6 +26,34 @@ namespace sprout {
 		inline SPROUT_CONSTEXPR T root_two() {
 			return 1.414213562373095048801688724209698078569671875376948073L;
 		}
+		//
+		// half_root_two
+		//
+		template<typename T>
+		inline SPROUT_CONSTEXPR T half_root_two() {
+			return 0.70710678118654752440084436210484903928483593756084L;
+		}
+		//
+		// e
+		//
+		template<typename T>
+		inline SPROUT_CONSTEXPR T e() {
+			return 2.7182818284590452353602874713526624977572470936999595749669676L;
+		}
+		//
+		// ln_ten
+		//
+		template<typename T>
+		inline SPROUT_CONSTEXPR T ln_ten() {
+			return 2.302585092994045684017991454684364207601101488628772976L;
+		}
+		//
+		// ln_two
+		//
+		template<typename T>
+		inline SPROUT_CONSTEXPR T ln_two() {
+			return 0.693147180559945309417232121458176568075500134360255254L;
+		}
 	}	// namespace math
 }	// namespace sprout
 
diff --git a/sprout/math/exponential.hpp b/sprout/math/exponential.hpp
index b441aee3..9cd437de 100644
--- a/sprout/math/exponential.hpp
+++ b/sprout/math/exponential.hpp
@@ -3,5 +3,8 @@
 
 #include <sprout/math/exp.hpp>
 #include <sprout/math/log.hpp>
+#include <sprout/math/log10.hpp>
+#include <sprout/math/log2.hpp>
+#include <sprout/math/log1p.hpp>
 
 #endif	// #ifndef SPROUT_MATH_EXPONENTIAL_HPP
diff --git a/sprout/math/log.hpp b/sprout/math/log.hpp
index a59fb3d9..18225cd0 100644
--- a/sprout/math/log.hpp
+++ b/sprout/math/log.hpp
@@ -53,7 +53,8 @@ namespace sprout {
 			inline SPROUT_CONSTEXPR FloatType
 			log(FloatType x) {
 				typedef double type;
-				return !(x > 0) ? -std::numeric_limits<FloatType>::infinity()
+				return x == 0 ? std::numeric_limits<FloatType>::quiet_NaN()
+					: !(x > 0) ? -std::numeric_limits<FloatType>::infinity()
 					: static_cast<FloatType>(sprout::math::detail::log_impl(x))
 					;
 			}
diff --git a/sprout/math/log10.hpp b/sprout/math/log10.hpp
new file mode 100644
index 00000000..ebacff58
--- /dev/null
+++ b/sprout/math/log10.hpp
@@ -0,0 +1,45 @@
+#ifndef SPROUT_MATH_LOG10_HPP
+#define SPROUT_MATH_LOG10_HPP
+
+#include <type_traits>
+#include <sprout/config.hpp>
+#include <sprout/math/log.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
+			log10(FloatType x) {
+				return sprout::math::detail::log(x) / sprout::math::ln_ten<FloatType>();
+			}
+
+			template<
+				typename IntType,
+				typename sprout::enabler_if<std::is_integral<IntType>::value>::type = sprout::enabler
+			>
+			inline SPROUT_CONSTEXPR double
+			log10(IntType x) {
+				return sprout::math::detail::log10(static_cast<double>(x));
+			}
+		}	// namespace detail
+
+#	if SPROUT_USE_BUILTIN_CMATH_FUNCTION
+		using std::log10;
+#	else
+		using sprout::math::detail::log10;
+#	endif
+	}	// namespace math
+
+	using sprout::math::log10;
+}	// namespace sprout
+
+#endif	// #ifndef SPROUT_MATH_LOG10_HPP
diff --git a/sprout/math/log1p.hpp b/sprout/math/log1p.hpp
new file mode 100644
index 00000000..8e1f4a0b
--- /dev/null
+++ b/sprout/math/log1p.hpp
@@ -0,0 +1,44 @@
+#ifndef SPROUT_MATH_LOG1P_HPP
+#define SPROUT_MATH_LOG1P_HPP
+
+#include <type_traits>
+#include <sprout/config.hpp>
+#include <sprout/math/log.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
+			log1p(FloatType x) {
+				return sprout::math::detail::log(1 + x);
+			}
+
+			template<
+				typename IntType,
+				typename sprout::enabler_if<std::is_integral<IntType>::value>::type = sprout::enabler
+			>
+			inline SPROUT_CONSTEXPR double
+			log1p(IntType x) {
+				return sprout::math::detail::log1p(static_cast<double>(x));
+			}
+		}	// namespace detail
+
+#	if SPROUT_USE_BUILTIN_CMATH_FUNCTION
+		using std::log1p;
+#	else
+		using sprout::math::detail::log1p;
+#	endif
+	}	// namespace math
+
+	using sprout::math::log1p;
+}	// namespace sprout
+
+#endif	// #ifndef SPROUT_MATH_LOG1P_HPP
diff --git a/sprout/math/log2.hpp b/sprout/math/log2.hpp
new file mode 100644
index 00000000..6e8e385f
--- /dev/null
+++ b/sprout/math/log2.hpp
@@ -0,0 +1,45 @@
+#ifndef SPROUT_MATH_LOG2HPP
+#define SPROUT_MATH_LOG2HPP
+
+#include <type_traits>
+#include <sprout/config.hpp>
+#include <sprout/math/log.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
+			log2(FloatType x) {
+				return sprout::math::detail::log(x) / sprout::math::ln_two<FloatType>();
+			}
+
+			template<
+				typename IntType,
+				typename sprout::enabler_if<std::is_integral<IntType>::value>::type = sprout::enabler
+			>
+			inline SPROUT_CONSTEXPR double
+			log2(IntType x) {
+				return sprout::math::detail::log2(static_cast<double>(x));
+			}
+		}	// namespace detail
+
+#	if SPROUT_USE_BUILTIN_CMATH_FUNCTION
+		using std::log2;
+#	else
+		using sprout::math::detail::log2;
+#	endif
+	}	// namespace math
+
+	using sprout::math::log2;
+}	// namespace sprout
+
+#endif	// #ifndef SPROUT_MATH_LOG2HPP