求一个数的平方根

Lisp - scheme方言

 1 (define (abs x) (if(< x 0) (- x) x))    
 2         
 3 (define (square x) (* x x))
 4 
 5 (define (average x y) (/ (+ x y ) 2))
 6 
 7 (define (improve guess x) (average guess (/ x guess)))
 8         
 9 (define (guess-enough? guess x) (< (abs (- (square guess) x)) 0.001))
10 
11 (define (sqrt-iter guess x) (if (guess-enough? guess x) guess (sqrt-iter (improve guess x) x)))
12     
13 (define (sqrt x) (sqrt-iter 1.0 x))

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原文地址：https://www.cnblogs.com/maduar/p/5517624.html