(defn normalize
  "Normalize a value N from one range to a new range.
   Returns the normalized value."
  [min-new-range max-new-range
   min-number max-number
   n]
  (+ min-new-range
     (* (/ (- n min-number)
           (- max-number min-number))
        (- max-new-range min-new-range))))

(def fit0->1 (partial normalize 0 1))
(def fit-1->1 (partial normalize -1 1))