Created
August 13, 2013 08:37
-
-
Save yakreved/6219090 to your computer and use it in GitHub Desktop.
sicp 2.10 Бен Битобор, системный программист-эксперт, смотрит через плечо Лизы и замечает:
неясно, что должно означать деление на интервал, пересекающий ноль. Модифицируйте
код Лизы так, чтобы программа проверяла это условие и сообщала об ошибке, если оно
возникает.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
(define (make-interval a b) (cons a b)) | |
(define (upper-bound x) (car x)) | |
(define (lower-bound x) (cdr x)) | |
(define (width x) (- (cdr x) (car x))) | |
(define (mul-interval x y) | |
(let ((p1 (* (lower-bound x) (lower-bound | |
y))) | |
(p2 (* (lower-bound x) (upper-bound | |
y))) | |
(p3 (* (upper-bound x) (lower-bound | |
y))) | |
(p4 (* (upper-bound x) (upper-bound | |
y)))) | |
(make-interval (min p1 p2 p3 p4) | |
(max p1 p2 p3 p4)))) | |
(define (div-interval x y) | |
(if (<= (* (lower-bound y) (upper-bound y)) 0) | |
(display '("Division by interval that spans zero" y)) | |
(mul-interval x | |
(make-interval (/ 1.0 (upper-bound y)) | |
(/ 1.0 (lower-bound y)))))) | |
(div-interval (make-interval 4 5) (make-interval -2 1)) |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment