SICP Exercise 1.7
Using absolute difference as a criteria for
good-enough? will not work for calculating square roots of smaller numbers. Changing it to be a ratio instead would work for both larger and smaller numbers.
(define (sqrt-iter guess x) (if (good-enough? guess) guess (sqrt-iter (improve guess x) x))) (define (improve guess x) (average guess (/ x guess))) (define (average x y) (/ (+ x y) 2)) (define (good-enough? guess old-guess) (< (/ old-guess guess) 0.001)) (define (square x) (* x x)) (define (sqrt x) (sqrt-iter 1.0 x))