Ex-1.29

(define (integral f a b n)
  (define (sum-iter partial-sum h count coefficient)
    (cond ((= count n)
           (+ partial-sum (f (+ a (* n h)))))
          ((= count 0)
           (sum-iter (+ partial-sum (f a)) h (+ count 1) 4))
          (else
           (sum-iter
            (+ partial-sum
               (* coefficient (f (+ a (* count h)))))
            h (+ count 1) (if (= coefficient 2) 4 2)))))
  (* (/ (/ (- b a) n) 3)
     (sum-iter 0 (/ (- b a) n) 0 1)))

(define (cube x) (* x x x))

1 ]=> (integral cube 0.0 1.0 100)
;Value: .25000000000000006
1 ]=> (integral cube 0.0 1.0 1000)
;Value: .25000000000000006