An Elisp function to calculate Wendler 5/3/1 main lift weights and reps given a week number and 1RM.

wendler531.el

(defun wendler (week one-rm)
  (let ((one-rm (* one-rm 0.9)))
    (if (eq week 4)
        (mapcar (lambda (n)
                  (format "%0.2fx5" n))
                (list (* one-rm 0.4)
                      (* one-rm 0.5)
                      (* one-rm 0.6)))
      (let ((pct (+ 0.6 (* week 0.05)))
            (reps (cond ((eq week 1) '(5 5 5))
                        ((eq week 2) '(3 3 3))
                        ((eq week 3) '(5 3 1))
                        ((eq week 4) '(5 5 5)))))
        (list (format "%0.2fx%d" (* one-rm pct)          (nth 0 reps))
              (format "%0.2fx%d" (* one-rm (+ pct 0.1))  (nth 1 reps))
              (format "%0.2fx%d+" (* one-rm (+ pct 0.2)) (nth 2 reps)))))))