Solve 1.16

sicp-ex-1.16.rkt

@@ -1,19 +1,16 @@
-; UNFINISHED
 (define (sqr n)
   (* n n))
 
 (define (fast-ext-iter number power product)
   (cond ((= power 0) product)
-        ((even? power) (fast-ext-iter number
+        ((even? power) (fast-ext-iter (sqr number)
                                       (/ power 2)
-                                      (if (= product 1)
+                                      product))
-                                          (sqr number)
-                                          (sqr product))))
         (else (fast-ext-iter number
                              (- power 1)
-                             (* power product)))))
+                             (* number product)))))
 
 (define (fast-ext number power)
   (fast-ext-iter number power 1))
 
-(fast-ext 2 8)
+(fast-ext 2 5)