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)))))
```