/** Named constructor from angle == exponential map at identity */
static Rot2 fromAngle(double theta) { return Rot2(cos(theta),sin(theta));}
/** Named constructor from cos(theta),sin(theta) pair, will *not* normalize! */
static Rot2 fromCosSin(double c, double s);
/** Named constructor that behaves as atan2, i.e., y,x order (!) and normalizes */
static Rot2 atan2(double y, double x);
which are a bit more verbose, but at least won't cause hours of bug-tracking :-(
I also made most compose, inverse, and rotate functions into methods, with the global functions mostly calling the methods. Methods have privileged access to members and hence are typically much more readable.
Frank Dellaert
Kai Ni
Chris Beall
Richard Roberts