AP_Math: correct descriptions of quaternion functions

libraries/AP_Math/quaternion.cpp

@@ -51,7 +51,7 @@ void QuaternionT<T>::rotation_matrix(Matrix3d &m) const
     m.c.z = 1.0f-2.0f*(q2q2 + q3q3);
 }
 
-// return the rotation matrix equivalent for this quaternion
+// populate the supplied rotation matrix equivalent from this quaternion
 template <typename T>
 void QuaternionT<T>::rotation_matrix(Matrix3f &m) const
 {
@@ -76,7 +76,7 @@ void QuaternionT<T>::rotation_matrix(Matrix3f &m) const
     m.c.z = 1.0f-2.0f*(q2q2 + q3q3);
 }
 
-// return the rotation matrix equivalent for this quaternion
+// make this quaternion equivalent to the supplied matrix
 // Thanks to Martin John Baker
 // http://www.euclideanspace.com/maths/geometry/rotations/conversions/matrixToQuaternion/index.htm
 template <typename T>

libraries/AP_Math/quaternion.h

@@ -63,11 +63,11 @@ public:
         return isnan(q1) || isnan(q2) || isnan(q3) || isnan(q4);
     }
 
-    // return the rotation matrix equivalent for this quaternion
+    // populate the supplied rotation matrix equivalent from this quaternion
     void        rotation_matrix(Matrix3f &m) const;
     void        rotation_matrix(Matrix3d &m) const;
 
-    // return the rotation matrix equivalent for this quaternion
+    // make this quaternion equivalent to the supplied matrix
     void		from_rotation_matrix(const Matrix3<T> &m);
 
     // create a quaternion from a given rotation