;this program does not work, it will cause an infinite loop

(define (sqrt_iter new_guess last_guess x)
	(new-if (good_enough? new_guess last_guess)
	  new_guess
	  (sqrt_iter (improve new_guess x) new_guess x)
	)
)

(define (new-if predicate then-clause else-clause)
	(cond (predicate then-clause)
		  (else else-clause)))

(define (improve guess x)
	(/ (+ guess (/ x guess)) 2))


(define (good_enough? guess last_guess) 
  (< (absolute (- guess last_guess)) 0.000000000000001))

(define (absolute x)
	(if (< x 0)
	  (- 0 x)
	  x))

(define (sqrt x) (sqrt_iter (/ x 2.0) x x))

(print (sqrt 10))