update

AlgImperSem008.scm

@@ -1,5 +1,7 @@
 @; scheme-r5rs
 
+;; runs only in gambit (gsi AlgImperSem008.smc)
+
 ;; (define-syntax bugger-or
 ;;   (syntax-rules ()
 ;;     [(_) #f]
@@ -337,3 +339,98 @@ parameter f of d, a free variable in the body of b."
 (pp (itak 1 12  8  4))  ; (1733 5)
 (pp (itak 1 18 12  6))  ; (63609 7)
 ;; (pp (itak 1 28 20 12))  ; (2493349 13)
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;  ____ ___ ____ ____
+;; / ___|_ _/ ___|  _ \
+;; \___ \| | |   | |_) |
+;;  ___) | | |___|  __/
+;; |____/___\____|_|
+
+;;   ___ _      ___
+;;  / __| |_   | __|
+;; | (__| ' \  |__ \
+;;  \___|_||_| |___/
+
+;; (define (gcd a b)
+;;   (if (= b 0)
+;;       a
+;;       (gcd b (remainder a b))))
+
+(define (factorial n)
+  (define (iter product counter)
+    (if (> counter n)
+        product
+        (iter (* counter product)
+              (+ counter 1))))
+  (iter 1 1))
+
+;;; Exercise 5.1:
+
+;;        +-----+     +--------+       +-----+
+;;         \ 1 /      |        |        \ 1 /
+;;          \ /       |        V         \ /
+;;           |        |   .--------.      |
+;;           |        |    \  +1   /      |
+;;          (X) p<-1  |     \_____/      (X) c<-1
+;;           |        |        |          |
+;;           |        |       (X) c<-c++  |
+;;           |        |        |          |
+;;           v        |        V          |
+;;        +-----+     |     +-----+       |   +-----+
+;;     +->|  p  |     +-----|  c  |<------+   |  n  |
+;;     |  +-----+           +-----+           +-----+
+;;     |     |                 |                 |
+;;     |     +------+   +------+------+   +------+
+;;     |            |   |             |   |
+;;     |         .--+---+--.       .--+---+--.
+;;     |          \   *   /         \   <   /
+;;     |           \_____/           \_____/
+;;     |              |                 |
+;;    (X) p<-t       (X) t<-pc         (X) t<-lt
+;;     |              |                 |
+;;     |              |                 V
+;;     |              |              +-----+
+;;     |              +------------->|     |
+;;     +-----------------------------|  t  |
+;;                                   |     |
+;;                                   +-----+
+;;                                      |
+;;                                      |
+;;                                      V
+;;                                     ---
+;;                                    /   \
+;;                                   | #t  |
+;;                                    \___/
+
+;;                          start
+;;                            |
+;;                            V
+;;                        +-------+
+;;                        |  c<-1 |
+;;                        +-------+
+;;                            |
+;;                            V
+;;                        +-------+
+;;                        |  p<-1 |
+;;                        +-------+
+;;                            |
+;;                            V
+;;                        +-------+
+;;                        | t<-lt |
+;;                        +-------+
+;;                            |
+;;                            V
+;;                           / \ yes
+;;                +-------->< < >-----> done (answer in reg. p)
+;;                |          \ /
+;;                |           | no
+;;                |           V
+;;                |       +-------+
+;;                |       | t<-pc |
+;;                |       +-------+
+;;                |           |
+;;                |           V
+;;            +-------+   +-------+
+;;            | c<-c++|<--|  p<-t |
+;;            +-------+   +-------+