(define (square x) (* x x)) (define (improve-cube y x) (/ (+ (/ x (square y)) (* 2 y)) 3.0)) (define (good-enough? previous guess) (< (abs (- (/ previous guess) 1.0)) 0.001)) (define (cubic-root-iter previous guess x) (if (good-enough? previous guess) guess (cubic-root-iter guess (improve-cube guess x) x))) (define (cubic-root x) (cubic-root-iter 1.0 x x))
