diff --git a/sprout/math.hpp b/sprout/math.hpp
index 6bcab616..b25e1f3d 100644
--- a/sprout/math.hpp
+++ b/sprout/math.hpp
@@ -11,5 +11,6 @@
 #include <sprout/config.hpp>
 #include <sprout/math/functions.hpp>
 #include <sprout/math/constants.hpp>
+#include <sprout/math/constant_variables.hpp>
 
 #endif	// #ifndef SPROUT_MATH_HPP
diff --git a/sprout/math/constant_variables.hpp b/sprout/math/constant_variables.hpp
index a3aae35d..028e2e0c 100644
--- a/sprout/math/constant_variables.hpp
+++ b/sprout/math/constant_variables.hpp
@@ -1,117 +1,122 @@
-/*=============================================================================
-  Copyright (c) 2014 fimbul
-  https://github.com/fimbul
-
-  Distributed under the Boost Software License, Version 1.0. (See accompanying
-  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
-=============================================================================*/
-#ifndef SPROUT_MATH_CONSTANT_VARIABLES_HPP
-#define SPROUT_MATH_CONSTANT_VARIABLES_HPP
-
-#include <sprout/config.hpp>
-#if SPROUT_USE_VARIABLE_TEMPLATES
-#   include <sprout/math/constants.hpp>
-#endif  // #if SPROUT_USE_VARIABLE_TEMPLATES
-
-namespace sprout {
-#if SPROUT_USE_VARIABLE_TEMPLATES
-  namespace math {
-    //
-    // pi
-    //
-    template<typename T>
-    SPROUT_STATIC_CONSTEXPR T pi_v = sprout::math::pi<T>();
-    //
-    // half_pi
-    //
-    template<typename T>
-    SPROUT_STATIC_CONSTEXPR T half_pi_v = sprout::math::half_pi<T>();
-    //
-    // third_pi
-    // two_thirds_pi
-    //
-    template<typename T>
-    SPROUT_STATIC_CONSTEXPR T third_pi_v = sprout::math::third_pi<T>();
-    template<typename T>
-    SPROUT_STATIC_CONSTEXPR T two_thirds_pi_v = sprout::math::two_thirds_pi<T>();
-    //
-    // quarter_pi
-    // three_quarters_pi
-    //
-    template<typename T>
-    SPROUT_STATIC_CONSTEXPR T quarter_pi_v = sprout::math::quarter_pi<T>();
-    template<typename T>
-    SPROUT_STATIC_CONSTEXPR T three_quarters_pi_v = sprout::math::three_quarters_pi<T>();
-    //
-    // two_pi
-    // four_pi
-    //
-    template<typename T>
-    SPROUT_STATIC_CONSTEXPR T two_pi_v = sprout::math::two_pi<T>();
-    template<typename T>
-    SPROUT_STATIC_CONSTEXPR T four_pi_v = sprout::math::four_pi<T>();
-    //
-    // two_div_pi
-    // root_two_div_pi
-    //
-    template<typename T>
-    SPROUT_STATIC_CONSTEXPR T two_div_pi_v = sprout::math::two_div_pi<T>();
-    template<typename T>
-    SPROUT_STATIC_CONSTEXPR T root_two_div_pi_v = sprout::math::root_two_div_pi<T>();
-    //
-    // root_pi
-    // one_div_root_pi
-    // root_one_div_pi
-    // two_div_root_pi
-    //
-    template<typename T>
-    SPROUT_STATIC_CONSTEXPR T root_pi_v = sprout::math::root_pi<T>();
-    template<typename T>
-    SPROUT_STATIC_CONSTEXPR T one_div_root_pi_v = sprout::math::one_div_root_pi<T>();
-    template<typename T>
-    SPROUT_STATIC_CONSTEXPR T root_one_div_pi_v = sprout::math::root_one_div_pi<T>();
-    template<typename T>
-    SPROUT_STATIC_CONSTEXPR T two_div_root_pi_v = sprout::math::two_div_root_pi<T>();
-    //
-    // half
-    // quarter
-    // third
-    // two_thirds
-    //
-    template<typename T>
-    SPROUT_STATIC_CONSTEXPR T half_v = sprout::math::half<T>();
-    template<typename T>
-    SPROUT_STATIC_CONSTEXPR T quarter_v = sprout::math::quarter<T>();
-    template<typename T>
-    SPROUT_STATIC_CONSTEXPR T third_v = sprout::math::third<T>();
-    template<typename T>
-    SPROUT_STATIC_CONSTEXPR T two_thirds_v = sprout::math::two_thirds<T>();
-    //
-    // root_two
-    // root_three
-    // half_root_two
-    //
-    template<typename T>
-    SPROUT_STATIC_CONSTEXPR T root_two_v = sprout::math::root_two<T>();
-    template<typename T>
-    SPROUT_STATIC_CONSTEXPR T root_three_v = sprout::math::root_three<T>();
-    template<typename T>
-    SPROUT_STATIC_CONSTEXPR T half_root_two_v = sprout::math::half_root_two<T>();
-    //
-    // e
-    //
-    template<typename T>
-    SPROUT_STATIC_CONSTEXPR T e_v = sprout::math::e<T>();
-    //
-    // ln_ten
-    // ln_two
-    //
-    template<typename T>
-    SPROUT_STATIC_CONSTEXPR T ln_ten_v = sprout::math::ln_ten<T>();
-    template<typename T>
-    SPROUT_STATIC_CONSTEXPR T ln_two_v = sprout::math::ln_two<T>();
-  } // namespace math
-#endif  // #if SPROUT_USE_VARIABLE_TEMPLATES
-} // namespace sprout
-
-#endif // #ifndef SPROUT_MATH_CONSTANT_VARIABLES_HPP
+/*=============================================================================
+  Copyright (c) 2014 fimbul
+  https://github.com/fimbul
+
+  Distributed under the Boost Software License, Version 1.0. (See accompanying
+  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+=============================================================================*/
+#ifndef SPROUT_MATH_CONSTANT_VARIABLES_HPP
+#define SPROUT_MATH_CONSTANT_VARIABLES_HPP
+
+#include <sprout/config.hpp>
+#if SPROUT_USE_VARIABLE_TEMPLATES
+#	include <sprout/math/constants.hpp>
+#endif  // #if SPROUT_USE_VARIABLE_TEMPLATES
+
+namespace sprout {
+	namespace math {
+#if SPROUT_USE_VARIABLE_TEMPLATES
+		//
+		// pi
+		//
+		template<typename T>
+		SPROUT_STATIC_CONSTEXPR T pi_v = sprout::math::pi<T>();
+		//
+		// half_pi
+		//
+		template<typename T>
+		SPROUT_STATIC_CONSTEXPR T half_pi_v = sprout::math::half_pi<T>();
+		//
+		// third_pi
+		// two_thirds_pi
+		//
+		template<typename T>
+		SPROUT_STATIC_CONSTEXPR T third_pi_v = sprout::math::third_pi<T>();
+		template<typename T>
+		SPROUT_STATIC_CONSTEXPR T two_thirds_pi_v = sprout::math::two_thirds_pi<T>();
+		//
+		// quarter_pi
+		// three_quarters_pi
+		//
+		template<typename T>
+		SPROUT_STATIC_CONSTEXPR T quarter_pi_v = sprout::math::quarter_pi<T>();
+		template<typename T>
+		SPROUT_STATIC_CONSTEXPR T three_quarters_pi_v = sprout::math::three_quarters_pi<T>();
+		//
+		// two_pi
+		// four_pi
+		//
+		template<typename T>
+		SPROUT_STATIC_CONSTEXPR T two_pi_v = sprout::math::two_pi<T>();
+		template<typename T>
+		SPROUT_STATIC_CONSTEXPR T four_pi_v = sprout::math::four_pi<T>();
+		//
+		// two_div_pi
+		// root_two_div_pi
+		//
+		template<typename T>
+		SPROUT_STATIC_CONSTEXPR T two_div_pi_v = sprout::math::two_div_pi<T>();
+		template<typename T>
+		SPROUT_STATIC_CONSTEXPR T root_two_div_pi_v = sprout::math::root_two_div_pi<T>();
+		//
+		// root_pi
+		// one_div_root_pi
+		// root_one_div_pi
+		// two_div_root_pi
+		//
+		template<typename T>
+		SPROUT_STATIC_CONSTEXPR T root_pi_v = sprout::math::root_pi<T>();
+		template<typename T>
+		SPROUT_STATIC_CONSTEXPR T one_div_root_pi_v = sprout::math::one_div_root_pi<T>();
+		template<typename T>
+		SPROUT_STATIC_CONSTEXPR T root_one_div_pi_v = sprout::math::root_one_div_pi<T>();
+		template<typename T>
+		SPROUT_STATIC_CONSTEXPR T two_div_root_pi_v = sprout::math::two_div_root_pi<T>();
+		//
+		// half
+		// quarter
+		// third
+		// two_thirds
+		//
+		template<typename T>
+		SPROUT_STATIC_CONSTEXPR T half_v = sprout::math::half<T>();
+		template<typename T>
+		SPROUT_STATIC_CONSTEXPR T quarter_v = sprout::math::quarter<T>();
+		template<typename T>
+		SPROUT_STATIC_CONSTEXPR T third_v = sprout::math::third<T>();
+		template<typename T>
+		SPROUT_STATIC_CONSTEXPR T two_thirds_v = sprout::math::two_thirds<T>();
+		//
+		// root_two
+		// root_three
+		// half_root_two
+		//
+		template<typename T>
+		SPROUT_STATIC_CONSTEXPR T root_two_v = sprout::math::root_two<T>();
+		template<typename T>
+		SPROUT_STATIC_CONSTEXPR T root_three_v = sprout::math::root_three<T>();
+		template<typename T>
+		SPROUT_STATIC_CONSTEXPR T half_root_two_v = sprout::math::half_root_two<T>();
+		//
+		// e
+		//
+		template<typename T>
+		SPROUT_STATIC_CONSTEXPR T e_v = sprout::math::e<T>();
+		//
+		// ln_ten
+		// ln_two
+		//
+		template<typename T>
+		SPROUT_STATIC_CONSTEXPR T ln_ten_v = sprout::math::ln_ten<T>();
+		template<typename T>
+		SPROUT_STATIC_CONSTEXPR T ln_two_v = sprout::math::ln_two<T>();
+		//
+		// phi
+		//
+		template<typename T>
+		SPROUT_STATIC_CONSTEXPR T phi_v = sprout::math::phi<T>();
+#endif	// #if SPROUT_USE_VARIABLE_TEMPLATES
+	}	// namespace math
+}	// namespace sprout
+
+#endif	// #ifndef SPROUT_MATH_CONSTANT_VARIABLES_HPP
diff --git a/sprout/math/constants.hpp b/sprout/math/constants.hpp
index 278320ad..f625a435 100644
--- a/sprout/math/constants.hpp
+++ b/sprout/math/constants.hpp
@@ -154,6 +154,13 @@ namespace sprout {
 		inline SPROUT_CONSTEXPR T ln_two() {
 			return static_cast<T>(0.693147180559945309417232121458176568075500134360255254120680009493393621969694715605863326996418687542001481021L);
 		}
+		//
+		// phi
+		//
+		template<typename T>
+		inline SPROUT_CONSTEXPR T phi() {
+			return static_cast<T>(1.61803398874989484820458683436563811772030917980576286213544862270526046281890244970720720418939113748475408807L);
+		}
 	}	// namespace math
 }	// namespace sprout