(define (sqrt-iter guess x) (if (good-enough? guess (improve guess x)) (improve guess x) (sqrt-iter (improve guess x) x)))
(define (improve guess x)(average guess (/ x guess)))
(define (average x y)(/ (+ x y) 2))
(define (good-enough? old-guess new-guess) (> 0.01 (/ (abs (- new-guess old-guess)) old-guess)))
(define (sqrta x)(sqrt-iter 1.0 x))
(define (square x)(* x x))
(sqrta 0.00009)
不再检测猜测值 guess 的平方与 x 之间的差，而是检测新旧两次猜测值之间的比率，当比率变化非常小时，程序就停止 improve
转载于:https://www.cnblogs.com/R4mble/p/7880746.html
相关资源：JAVA上百实例源码以及开源项目