blob: 9bda339d02c35bfbfdd69140dfd568477a46e6ba (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
|
;;; Under Creative Commons Attribution-ShareAlike 4.0
;;; International. See
;;; <https://creativecommons.org/licenses/by-sa/4.0/>.
(define-module (net ricketyspace sicp one seven)
#:export (tolerances-and-sqrt
good-enough-alt?
sqrt-iter-alt
sqrt-sicp-alt))
(use-modules (one six))
;;;; start yak shaving
(define (gen-good-enough tolerance)
(lambda (guess x)
(< (abs (- (square guess) x)) tolerance)))
(define (sqrt-iter-with-tolerance guess x tolerance)
(let ((good-enough? (gen-good-enough tolerance)))
(if (good-enough? guess x)
guess
(sqrt-iter-with-tolerance (improve guess x)
x tolerance))))
(define (sqrt-with-tolerance x tolerance)
(sqrt-iter-with-tolerance 1.0 x tolerance))
(define (tolerances-and-sqrt x tolerance)
(let* ((guile-sqrt (sqrt x))
(custom-sqrt (sqrt-with-tolerance x tolerance)))
(if (eqv? guile-sqrt custom-sqrt)
(cons tolerance custom-sqrt)
(cons (cons tolerance custom-sqrt)
(tolerances-and-sqrt x (/ tolerance 10))))))
;;;; end yak shaving
;;; start excercise 1.1.7
(define (good-enough-alt? guess prev-guess)
(< (abs (- guess prev-guess)) 0.001))
(define (sqrt-iter-alt guess prev-guess x)
(if (good-enough-alt? guess prev-guess)
guess
(sqrt-iter-alt (improve guess x) guess
x)))
(define (sqrt-sicp-alt x)
(sqrt-iter-alt 1.0 2.0 x))
;;;; end excercise 1.1.7
|
