Math: rotation dual complex number.

src/Math/Complex.h

@@ -140,6 +140,7 @@ template<class T> class Complex {
          * @f[
          *      \theta = atan2(b, a)
          * @f]
+         * @see rotation(), DualComplex::rotationAngle()
          */
         inline Rad<T> rotationAngle() const {
             return Rad<T>(std::atan2(_imaginary, _real));

src/Math/DualComplex.h

@@ -35,6 +35,20 @@ template<class T> class DualComplex: public Dual<Complex<T>> {
     public:
         typedef T Type;                         /**< @brief Underlying data type */
 
+        /**
+         * @brief Rotation dual complex number
+         * @param angle         Rotation angle (counterclockwise)
+         *
+         * @f[
+         *      \hat c = (cos \theta + i sin \theta) + \epsilon (0 + i0)
+         * @f]
+         * @see rotationAngle(), Complex::rotation(), Matrix3::rotation(),
+         *      DualQuaternion::rotation()
+         */
+        inline static DualComplex<T> rotation(Rad<T> angle) {
+            return {Complex<T>::rotation(angle), {{}, {}}};
+        }
+
         /**
          * @brief Default constructor
          *
@@ -58,6 +72,18 @@ template<class T> class DualComplex: public Dual<Complex<T>> {
          */
         inline constexpr /*implicit*/ DualComplex(const Complex<T>& real, const Complex<T>& dual): Dual<Complex<T>>(real, dual) {}
 
+        /**
+         * @brief Rotation angle of dual complex number
+         *
+         * @f[
+         *      \theta = atan2(b_0, a_0)
+         * @f]
+         * @see rotation(), Complex::rotationAngle()
+         */
+        inline Rad<T> rotationAngle() const {
+            return this->real().rotationAngle();
+        }
+
         /**
          * @brief Complex-conjugated dual complex number
          *

src/Math/DualQuaternion.h

@@ -38,15 +38,15 @@ template<class T> class DualQuaternion: public Dual<Quaternion<T>> {
 
         /**
          * @brief Rotation dual quaternion
-         * @param angle             Rotation angle (counterclockwise, in radians)
+         * @param angle             Rotation angle (counterclockwise)
          * @param normalizedAxis    Normalized rotation axis
          *
          * Expects that the rotation axis is normalized. @f[
          *      \hat q = [\boldsymbol a \cdot sin \frac \theta 2, cos \frac \theta 2] + \epsilon [\boldsymbol 0, 0]
          * @f]
          * @see rotationAngle(), rotationAxis(), Quaternion::rotation(),
-         *      Matrix4::rotation(), Vector3::xAxis(), Vector3::yAxis(),
-         *      Vector3::zAxis()
+         *      Matrix4::rotation(), DualComplex::rotation(), Vector3::xAxis(),
+         *      Vector3::yAxis(), Vector3::zAxis()
          */
         inline static DualQuaternion<T> rotation(Rad<T> angle, const Vector3<T>& normalizedAxis) {
             return {Quaternion<T>::rotation(angle, normalizedAxis), {{}, T(0)}};

src/Math/Matrix3.h

@@ -64,7 +64,7 @@ template<class T> class Matrix3: public Matrix<3, T> {
          * @brief 2D rotation matrix
          * @param angle     Rotation angle (counterclockwise)
          *
-         * @see rotation() const, Complex::rotation(),
+         * @see rotation() const, Complex::rotation(), DualComplex::rotation(),
          *      Matrix4::rotation(Rad, const Vector3&)
          */
         static Matrix3<T> rotation(Rad<T> angle) {

src/Math/Matrix4.h

@@ -76,9 +76,9 @@ template<class T> class Matrix4: public Matrix<4, T> {
          *
          * Expects that the rotation axis is normalized. If possible, use
          * faster alternatives like rotationX(), rotationY() and rotationZ().
-         * @see rotation() const, DualQuaternion::rotation(),
-         *      Quaternion::rotation(), Matrix3::rotation(Rad), Vector3::xAxis(),
-         *      Vector3::yAxis(), Vector3::zAxis()
+         * @see rotation() const, Quaternion::rotation(), DualQuaternion::rotation(),
+         *      Matrix3::rotation(Rad), Vector3::xAxis(), Vector3::yAxis(),
+         *      Vector3::zAxis()
          */
         static Matrix4<T> rotation(Rad<T> angle, const Vector3<T>& normalizedAxis) {
             CORRADE_ASSERT(MathTypeTraits<T>::equals(normalizedAxis.dot(), T(1)),

src/Math/Quaternion.h

@@ -175,7 +175,7 @@ template<class T> class Quaternion {
          * Expects that the quaternion is normalized. @f[
          *      \theta = 2 \cdot acos q_S
          * @f]
-         * @see rotationAxis(), rotation()
+         * @see rotationAxis(), rotation(), DualQuaternion::rotationAngle()
          */
         inline Rad<T> rotationAngle() const {
             CORRADE_ASSERT(MathTypeTraits<T>::equals(dot(), T(1)),

src/Math/Test/DualComplexTest.cpp

@@ -39,9 +39,13 @@ class DualComplexTest: public Corrade::TestSuite::Tester {
         void inverted();
         void invertedNormalized();
 
+        void rotation();
+
         void debug();
 };
 
+typedef Math::Deg<float> Deg;
+typedef Math::Rad<float> Rad;
 typedef Math::Complex<float> Complex;
 typedef Math::Dual<float> Dual;
 typedef Math::DualComplex<float> DualComplex;
@@ -62,6 +66,8 @@ DualComplexTest::DualComplexTest() {
              &DualComplexTest::inverted,
              &DualComplexTest::invertedNormalized,
 
+             &DualComplexTest::rotation,
+
              &DualComplexTest::debug);
 }
 
@@ -149,6 +155,12 @@ void DualComplexTest::invertedNormalized() {
     CORRADE_COMPARE(inverted, b/Math::sqrt(Dual(7.25f, -43.5f)));
 }
 
+void DualComplexTest::rotation() {
+    DualComplex a = DualComplex::rotation(Deg(120.0f));
+    CORRADE_COMPARE(a, DualComplex({-0.5f, 0.8660254f}, {0.0f, 0.0f}));
+    CORRADE_COMPARE_AS(a.rotationAngle(), Deg(120.0f), Rad);
+}
+
 void DualComplexTest::debug() {
     std::ostringstream o;