This took a ridiculous amount of time to hack together, but here’s a Common Lisp function to decide the shortest angle between two other angles. It’s used in the example of seeking a point above. I can now add noise to this to make a more AARON-style pen.
(defun shortest-angle-difference (a1 a2) "Find the shortest positive or negative distance between two angles." ;; This was slowly assembled from various online sources, none of which worked ;; Normalize angles to 0..2pi (let ((from (mod a1 +radian+)) (to (mod a2 +radian+))) ;; If from and to are equal (0 = 2pi radians) the angle is zero (if (or (= from to) (= (+ from to) +radian+)) 0.0d0 (let ((angle (- to from))) (if (> (abs angle) pi) ;; Please simplify me (* (- (signum angle)) (- +radian+ (abs angle))) angle)))))