#lang scheme

; We dont have closures at the time of writing, but each func gets its own env
; http://sarabander.github.io/sicp/html/1_002e1.xhtml#g_t1_002e1_002e7

(define (sqrt-iter guess x)
  (if (good-enough? guess x) guess (sqrt-iter (improve guess x) x)))

(define (improve guess x)
  (average guess (/ x guess)))

(define (average x y)
  (/ (+ x y) 2))

(define (square x)
  (* x x))

(define (good-enough? guess x)
  (< (abs (- (square guess) x)) 0.001))

(define (sqrt x)
  (sqrt-iter 1.0 x))

(display (sqrt 2))