generators for a rank-2 temperament

generators.ss

;; computes TE-optimal generators for a pair of vals
;; e.g. (generators '(1 2 4) '(0 -1 -4) '(2 3 5)) => (1201.397 504.348)

(define generators
   (lambda (val1 val2 basis)
      (let* ((square (lambda (x) (* x x)))
             (log2 (lambda (x) (/ (log x) (log 2))))
             (mean (lambda (ls) (/ (apply + ls) (length ls))))
             (w1 (map / val1 (map log2 basis)))
             (w2 (map / val2 (map log2 basis)))
             (mw1 (mean w1))
             (mw2 (mean w2))
             (msqw1 (mean (map square w1)))
             (msqw2 (mean (map square w2)))
             (mw12  (mean (map * w1 w2)))
             (common (/ 1200 (- (* msqw1 msqw2) (square mw12)))))
         (list (* common (- (* mw1 msqw2) (* mw2 mw12)))
               (* common (- (* mw2 msqw1) (* mw1 mw12)))))))