Math: no need to provide implementation just for Doxygen.

src/Math/Functions.h

@@ -84,7 +84,7 @@ UnsignedInt MAGNUM_EXPORT log(UnsignedInt base, UnsignedInt number);
 
 /** @brief Sine */
 #ifdef DOXYGEN_GENERATING_OUTPUT
-template<class T> inline T sin(Rad<T> angle) { return std::sin(T(angle)); }
+template<class T> inline T sin(Rad<T> angle);
 #else
 template<class T> inline T sin(Unit<Rad, T> angle) { return std::sin(T(angle)); }
 template<class T> inline T sin(Unit<Deg, T> angle) { return sin(Rad<T>(angle)); }
@@ -92,7 +92,7 @@ template<class T> inline T sin(Unit<Deg, T> angle) { return sin(Rad<T>(angle));
 
 /** @brief Cosine */
 #ifdef DOXYGEN_GENERATING_OUTPUT
-template<class T> inline T cos(Rad<T> angle) { return std::cos(T(angle)); }
+template<class T> inline T cos(Rad<T> angle);
 #else
 template<class T> inline T cos(Unit<Rad, T> angle) { return std::cos(T(angle)); }
 template<class T> inline T cos(Unit<Deg, T> angle) { return cos(Rad<T>(angle)); }
@@ -100,7 +100,7 @@ template<class T> inline T cos(Unit<Deg, T> angle) { return cos(Rad<T>(angle));
 
 /** @brief Tangent */
 #ifdef DOXYGEN_GENERATING_OUTPUT
-template<class T> inline T tan(Rad<T> angle) { return std::tan(T(angle)); }
+template<class T> inline T tan(Rad<T> angle);
 #else
 template<class T> inline T tan(Unit<Rad, T> angle) { return std::tan(T(angle)); }
 template<class T> inline T tan(Unit<Deg, T> angle) { return tan(Rad<T>(angle)); }