Math: added sincos().

Mainly a convenience function in case you want to compute sin and cos of
the same, potentially longer expression, and you don't want to have
repeated code or temporary variables. On some architectures might use
faster instruction that computes both values in one shot.

src/Magnum/Math/Functions.h

@@ -104,7 +104,11 @@ template<class Integral> std::pair<Integral, Integral> div(Integral x, Integral
 /* The functions accept Unit instead of Rad to make them working with operator
    products (e.g. 2*35.0_degf, which is of type Unit) */
 
-/** @brief Sine */
+/**
+@brief Sine
+
+@see @ref sincos()
+*/
 #ifdef DOXYGEN_GENERATING_OUTPUT
 template<class T> inline T sin(Rad<T> angle);
 #else
@@ -112,7 +116,11 @@ 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)); }
 #endif
 
-/** @brief Cosine */
+/**
+@brief Cosine
+
+@see @ref sincos()
+*/
 #ifdef DOXYGEN_GENERATING_OUTPUT
 template<class T> inline T cos(Rad<T> angle);
 #else
@@ -120,6 +128,21 @@ 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)); }
 #endif
 
+/**
+@brief Sine and cosine
+
+On some architectures might be faster than doing both computations separately.
+@see @ref sin(), @ref cos()
+*/
+#ifdef DOXYGEN_GENERATING_OUTPUT
+template<class T> inline std::pair<T, T> sincos(Rad<T> angle);
+#else
+template<class T> inline std::pair<T, T> sincos(Unit<Rad, T> angle) {
+    return {std::sin(T(angle)) ,std::cos(T(angle))};
+}
+template<class T> inline std::pair<T, T> sincos(Unit<Deg, T> angle) { return sincos(Rad<T>(angle)); }
+#endif
+
 /** @brief Tangent */
 #ifdef DOXYGEN_GENERATING_OUTPUT
 template<class T> inline T tan(Rad<T> angle);

src/Magnum/Math/Test/FunctionsTest.cpp

@@ -453,6 +453,9 @@ void FunctionsTest::trigonometric() {
     CORRADE_COMPARE(Math::cos(Rad(Constants::pi()/3)), 0.5f);
     CORRADE_COMPARE_AS(Math::acos(0.5f), Deg(60.0f), Deg);
 
+    CORRADE_COMPARE(Math::sincos(Deg(30.0f)), std::make_pair(0.5f, 0.8660254037844386f));
+    CORRADE_COMPARE(Math::sincos(Rad(Constants::pi()/6)), std::make_pair(0.5f, 0.8660254037844386f));
+
     CORRADE_COMPARE(Math::tan(Deg(45.0f)), 1.0f);
     CORRADE_COMPARE(Math::tan(Rad(Constants::pi()/4)), 1.0f);
     CORRADE_COMPARE_AS(Math::atan(1.0f), Deg(45.0f), Deg);
@@ -469,6 +472,9 @@ void FunctionsTest::trigonometricWithBase() {
     CORRADE_COMPARE(Math::cos(2*Deg(30.0f)), 0.5f);
     CORRADE_COMPARE(Math::cos(2*Rad(Constants::pi()/6)), 0.5f);
 
+    CORRADE_COMPARE(Math::sincos(2*Deg(15.0f)), std::make_pair(0.5f, 0.8660254037844386f));
+    CORRADE_COMPARE(Math::sincos(2*Rad(Constants::pi()/12)), std::make_pair(0.5f, 0.8660254037844386f));
+
     CORRADE_COMPARE(Math::tan(2*Deg(22.5f)), 1.0f);
     CORRADE_COMPARE(Math::tan(2*Rad(Constants::pi()/8)), 1.0f);
 }