1.31.scm

;; Recursive product 
(define (product term a next b)
  (if (> a b)
      1
      (* (term a)
         (product term (next a) next b))))

;; Iterative product

(define (product term a next b)
  (define (iter a result)
    (if (> a b)
        result
        (iter (next a) (* (term a) result))))
  (iter a 1))