(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))