(define sqrt
  (lambda (x)
    (sqrt-iter 1 x)))

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

(define improve
  (lambda (G x)
    (average G (/ x G))))

(define average
  (lambda (a b)
    (/ (+ a b) 2)))

(define good-enough?
  (lambda (G x)
    (< (abs (- (* G G) x)) .001)))