- better description for quaternion class

- revert conversion functions to constructor

matrix/Dcm.hpp

@@ -78,32 +78,6 @@ public:
      * @param q quaternion to set dcm to
      */
     Dcm(const Quaternion<Type> & q) {
-        set_from_quaternion(q);
-    }
-
-    /**
-     * Constructor from euler angles
-     *
-     * This sets the transformation matrix from frame 2 to frame 1 where the rotation
-     * from frame 1 to frame 2 is described by a 3-2-1 intrinsic Tait-Bryan rotation sequence.
-     *
-     *
-     * @param euler euler angle instance
-     */
-    Dcm(const Euler<Type> & euler) {
-        set_from_euler(euler);
-    }
-
-
-    /**
-     * Set from quaternion
-     *
-     * Instance is set from quaternion representing
-     * transformation from frame 2 to frame 1.
-     *
-     * @param q quaternion to set dcm to
-     */
-    void set_from_quaternion(const Quaternion<Type> & q) {
         Dcm &dcm = *this;
         Type a = q(0);
         Type b = q(1);
@@ -125,14 +99,15 @@ public:
     }
 
     /**
-     * Set from euler angles
+     * Constructor from euler angles
      *
-     * This provides the transformation matrix from frame 2 to frame 1 where the rotation
+     * This sets the transformation matrix from frame 2 to frame 1 where the rotation
-     * from frame 1 to frame 2 is described by a 3-2-1 intrinsic Tait-Bryan rotation sequence
+     * from frame 1 to frame 2 is described by a 3-2-1 intrinsic Tait-Bryan rotation sequence.
      *
-     * @param euler euler angle instannce
+     *
+     * @param euler euler angle instance
      */
-    void set_from_euler(const Euler<Type> & euler) {
+    Dcm(const Euler<Type> & euler) {
         Dcm &dcm = *this;
         Type cosPhi = Type(cos(euler.phi()));
         Type sinPhi = Type(sin(euler.phi()));

matrix/Euler.hpp

@@ -82,7 +82,9 @@ public:
      */
     Euler(Type phi_, Type theta_, Type psi_) : Vector<Type, 3>()
     {
-        set_from_euler(phi_, theta_, psi_);
+        phi() = phi_;
+        theta() = theta_;
+        psi() = psi_;
     }
 
     /**
@@ -96,54 +98,6 @@ public:
      * @param dcm Direction cosine matrix
     */
     Euler(const Dcm<Type> & dcm) : Vector<Type, 3>()
-    {
-        set_from_dcm(dcm);
-    }
-
-    /**
-     * Constructor from quaternion instance.
-     *
-     * Instance is set from a quaternion representing transformation
-     * from frame 2 to frame 1.
-     * This instance will hold the angles defining the 3-2-1 intrinsic
-     * Tait-Bryan rotation sequence from frame 1 to frame 2.
-     *
-     * @param q quaternion
-    */
-    Euler(const Quaternion<Type> & q) :
-        Vector<Type, 3>()
-    {
-        set_from_quaternion(q);
-    }
-
-    /**
-     * Set from euler angles
-     *
-     * Instance is set from an 3-2-1 intrinsic Tait-Bryan rotation
-     * sequence representing transformation from frame 1 to frame 2.  
-     *
-     * @param phi_ rotation angle about X axis
-     * @param theta_ rotation angle about Y axis
-     * @param psi_ rotation angle about Z axis
-     */
-    void set_from_euler(Type phi_, Type theta_, Type psi_)
-    {
-        phi() = phi_;
-        theta() = theta_;
-        psi() = psi_;
-    }
-
-    /**
-     * Set from DCM matrix
-     *
-     * Instance is set from Dcm representing transformation from
-     * frame 2 to frame 1.
-     * This instance will hold the angles defining the 3-2-1 intrinsic
-     * Tait-Bryan rotation sequence from frame 1 to frame 2.
-     *
-     * @param dcm Direction cosine matrix
-     */
-    void set_from_dcm(const Dcm<Type> & dcm)
     {
         Type phi_val = Type(atan2(dcm(2,1), dcm(2,2)));
         Type theta_val = Type(asin(-dcm(2,0)));
@@ -164,7 +118,7 @@ public:
     }
 
     /**
-     * Set from quaternion instance.
+     * Constructor from quaternion instance.
      *
      * Instance is set from a quaternion representing transformation
      * from frame 2 to frame 1.
@@ -172,8 +126,9 @@ public:
      * Tait-Bryan rotation sequence from frame 1 to frame 2.
      *
      * @param q quaternion
-     */
+    */
-    void set_from_quaternion(const Quaternion<Type> & q)
+    Euler(const Quaternion<Type> & q) :
+        Vector<Type, 3>()
     {
         *this = Euler(Dcm<Type>(q));
     }

matrix/Quaternion.hpp

@@ -3,8 +3,13 @@
  *
  * All rotations and axis systems follow the right-hand rule.
  *
- * A quaternion instance of this class describes a rotation from
+ * In order to rotate a vector v by a righthand rotation defined by the quaternion q
- * coordinate frame 1 to coordinate frame 2. The first element of the quaternion
+ * one can use the following operation:
+ * v_rotated = q^(-1) * [0;v] * q
+ * where q^(-1) represents the inverse of the quaternion q.
+ * The product z of two quaternions z = q1 * q2 represents an intrinsic rotation
+ * in the order of first q1 followed by q2.
+ * The first element of the quaternion
  * represents the real part, thus, a quaternion representing a zero-rotation
  * is defined as (1,0,0,0).
  *
@@ -84,7 +89,15 @@ public:
     Quaternion(const Dcm<Type> & dcm) :
         Vector<Type, 4>()
     {
-        set_from_dcm(dcm);
+        Quaternion &q = *this;
+        q(0) = Type(0.5 * sqrt(1 + dcm(0, 0) +
+                               dcm(1, 1) + dcm(2, 2)));
+        q(1) = Type((dcm(2, 1) - dcm(1, 2)) /
+                    (4 * q(0)));
+        q(2) = Type((dcm(0, 2) - dcm(2, 0)) /
+                    (4 * q(0)));
+        q(3) = Type((dcm(1, 0) - dcm(0, 1)) /
+                    (4 * q(0)));
     }
 
     /**
@@ -98,59 +111,6 @@ public:
      */
     Quaternion(const Euler<Type> & euler) :
         Vector<Type, 4>()
-    {
-        set_from_euler(euler);
-    }
-
-    /**
-     * Constructor from quaternion values
-     *
-     * Instance is initialized from quaternion values representing coordinate
-     * transformation from frame 2 to frame 1.
-     * A zero-rotation quaternion is represented by (1,0,0,0).
-     *
-     * @param a set quaternion value 0
-     * @param b set quaternion value 1
-     * @param c set quaternion value 2
-     * @param d set quaternion value 3
-     */
-    Quaternion(Type a, Type b, Type c, Type d) :
-        Vector<Type, 4>()
-    {
-        set_from_quaternion(a, b, c, d);
-    }
-
-    /**
-     * Set from dcm
-     *
-     * Instance is set from a dcm representing coordinate transformation
-     * from frame 2 to frame 1.
-     *
-     * @param dcm dcm to set quaternion to
-     */
-    void set_from_dcm(const Dcm<Type> & dcm)
-    {
-        Quaternion &q = *this;
-        q(0) = Type(0.5 * sqrt(1 + dcm(0, 0) +
-                               dcm(1, 1) + dcm(2, 2)));
-        q(1) = Type((dcm(2, 1) - dcm(1, 2)) /
-                    (4 * q(0)));
-        q(2) = Type((dcm(0, 2) - dcm(2, 0)) /
-                    (4 * q(0)));
-        q(3) = Type((dcm(1, 0) - dcm(0, 1)) /
-                    (4 * q(0)));
-    }
-
-    /**
-     * Set from euler angles
-     *
-     * This sets the instance to a quaternion representing coordinate transformation from
-     * frame 2 to frame 1 where the rotation from frame 1 to frame 2 is described
-     * by a 3-2-1 intrinsic Tait-Bryan rotation sequence.
-     *
-     * @param euler euler angles to set quaternion to
-     */
-    void set_from_euler(const Euler<Type> & euler)
     {
         Quaternion &q = *this;
         Type cosPhi_2 = Type(cos(euler.phi() / (Type)2.0));
@@ -170,17 +130,19 @@ public:
     }
 
     /**
-     * Set from quaternion values
+     * Constructor from quaternion values
      *
-     * Instance is set from quaternion values representing coordinate
+     * Instance is initialized from quaternion values representing coordinate
      * transformation from frame 2 to frame 1.
+     * A zero-rotation quaternion is represented by (1,0,0,0).
      *
      * @param a set quaternion value 0
      * @param b set quaternion value 1
      * @param c set quaternion value 2
      * @param d set quaternion value 3
      */
-    void set_from_quaternion(Type a, Type b, Type c, Type d)
+    Quaternion(Type a, Type b, Type c, Type d) :
+        Vector<Type, 4>()
     {
         Quaternion &q = *this;
         q(0) = a;