#lang sicp

(define (improve y x)
  (/ (+ (/ x (* y y)) (* 2 y)) 3))

; Fractional good-enough like in ex 1-7
(define (good-enough? guessL guessLL) 
  (< (/ (abs (- guessL guessLL)) guessL) 0.01))

(define (curt-iter guessL guessLL x)
  (if (good-enough? guessL guessLL)
      guessL
      (curt-iter (improve guessL x) guessL x)))

(define (my-curt x)
  (curt-iter 1.0 1.1 x))

; 1.4422495703074083
(my-curt 3)