adding ex1-18

emkay · Jul 11, 2010 · 74ed777 · 74ed777
1 parent 4387fda
commit 74ed777
Showing 1 changed file with 14 additions and 0 deletions.
diff --git a/chapter1/ex1-18.ss b/chapter1/ex1-18.ss
@@ -0,0 +1,14 @@
+(define (double a)
+  (+ a a))
+
+(define (halve a)
+  (/ a 2))
+
+(define (new-* a b)
+  (new-*-iter 0 a b))
+
+(define (new-*-iter p a counter)
+  (cond ((= counter 0) p)
+        ((even? counter)
+         (new-*-iter p (double a) (halve counter)))
+        (else (new-*-iter (+ p a) a (- counter 1)))))