ex01_1.38.scm

ex01_1.38.scm

#lang sicp

(define (cont-d i)
  (let ((n (floor (/ (+ i 1) 3))))
    (if (= 0 (remainder (+ i 1) 3))
      (* 2 n)
      1)))

(define (cont-frac n d k)
  (define (iter i result)
    (if (< i 1)
        result
        (iter (- i 1)
              (/ (n i)
                 (+ (d i) result)))))
  (iter k 1))

(define (cont-frac-iter n d k)
  (define (iter i result)
      (if (= k i)
          result
          (iter (+ i 1)
                (/ (n i)
                   (+ (d i) result)))))
  (iter 1 1))

(cont-frac (lambda (i) 1.0)
           (lambda (i) 1.0)
           30000)

(cont-frac-iter (lambda (i) 1.0)
                (lambda (i) 1.0)
                30000)

(cont-frac (lambda (i) 1.0)
           cont-d
           30000)

(cont-frac-iter (lambda (i) 1.0)
                cont-d
                30000)
                
;;; result 
; 0.6180339887498948
; 0.6180339887498948
; 0.7182818284590453
; 4.999874999999922e-05