1 (define (* a b)
2   (if (= b 0)
3       0
4       (+ a (* a (- b 1)))))
5 
6 ;; a * b = {
7 ;; 	 0 if b = 0,
8 ;; 	 2 * a * (b/2) if b is even,
9 ;; 	 a + a * (b-1) if b is odd
10 ;; }
11 
12 (define (fast-mult a b)
13   (cond ((= b 0) 0)
14 	((even? b) (double (* a (halve b))))
15 	(else (+ a (* a (- b 1))))))
16 
17 (define (test-case actual expected)
18   (load-option 'format)
19   (newline)
20   (format #t "Actual: ~A Expected: ~A" actual expected))
21 (test-case (fast-expt-iter 2 1 0) 2)