(define (new-if predicate then-clause else-clause)
(cond (predicate then-clause)
(else else-clause)))
(define (sqrt x)
(define (sqrt-iter guess x)
(new-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 (good-enough? guess x)
(< (abs (- (square guess) x)) 0.001))
(sqrt-iter 1.0 x))