if

(define (sqroot x)
		(sqrt-iter 1.0 x))
(define (sqrt-iter guess x)
	(if (good-enough? guess x)
		guess
		(sqrt-iter (improve guess x)
					x)))
(define (good-enough? guess x)
		(< (abs (- (square guess) x)) 0.001))
(define (improve guess x)
		(average guess (/ x guess)))
(define (average x y)
		(/ (+ x y) 2))
(define (square x)
		(* x x))

Example:
1)	(sqroot 4)
2)	(sqrt-iter 1 4)
3)	(if (good-enough? 1 4)
		1
		(sqrt-iter (improve 1 4)
					4))
4)	(good-enough? 1 4)
		(< (abs (- (square 1) 4)) 0.001))

5)	(square 1)
	(* 1 1)

Answer: 1

6)	(< (abs (- 1 4)) 0.001))
		(< (abs -3) 0.001))
		(< 3 0.001))

Answer: #false

7)	(sqrt-iter (improve 1 4)
					4)

8)	(average 1 (/ 4 1)))

9)	(/ 4 1)

Answer: 4

10)	(average 1 4))
11)	(/ (+ 1 4)
		2))
12)	(+ 1 4)

Answer: 5

13)	(/ 5 2)

Answer: 2.5

14) (sqrt-iter 2.5 4)
15)	p.3 etc.