sicp 2.1

改进版有理数构造函数

最新推荐文章于 2024-09-07 13:44:00 发布

原创最新推荐文章于 2024-09-07 13:44:00 发布 · 93 阅读

0 ·

CC 4.0 BY-SA版权

SICP 专栏收录该内容

62 篇文章

订阅专栏

本文介绍了一个改进版的make-rat函数，该函数能够处理正数和负数参数，并确保有理数规范化：若为正数，则分子和分母均为正；若为负数，则仅分子为负。

Exercise 2.1. Define a better version of make-rat that handles both positive and negative arguments. Make-rat should normalize the sign so that if the rational number is positive, both the numerator and denominator are positive, and if the rational number is negative, only the numerator is negative.

(define (make-rat n d)
  (cond ((and (> n 0) (> d 0)) (cons n d))
        ((and (< n 0) (< d 0)) (cons (- n) (-d )))
        (else (cons (- (abs n)) (abs d)))))

(define (numer x)
  (car x))

(define (denom x)
  (cdr x))