Re[2]: 1. warnings 2. optimizations

[sshteingold@cctrading.com]

A better approach to the treatment of line numbers in CLISP would be 
needed for this. But you can customize your ~/.emacs :
     
     Is there a chance that CLISP will learn to treat line numbers in a 
     more "modern" way? :-)
      
      ;; Meta-g :== Meta-x goto-line
      (global-set-key "\M-g" 'goto-line)
     
     Errr... M-g is already bound in the standard Emacs. (I use f12 for 
     goto-line).
     
>      2. The following 3 functions compute factorial: 
>      ...
>      I would expect more difference between fac0 and (fac1 and fac2) than  
>      between fac1 and fac2. And I definitely did not expect much difference 
>      between fac 1 and fac2.
     
fac0 and fac2 are the same algorithm (they multiply the same numbers in the 
same order), just in a different look.
     
     A recent discussion in comp.lang.lisp made me think that a good lisp 
     compiler should compile tail-recursion to a better code than 
     iteration. The iterative version of factorial takes one gc more than 
     the tail-recursive one.     
     
>      On a second thought... The reason must be that we get to the bignums 
>      faster with fac0 and fac2!
     
You are in the bignums nearly all the time (already after 15 multiplications 
out of 10000). That cannot account for a 12% speedup. Think once more. 
(Hint: In clisp, the time needed for the multiplication of a fixnum with
a bignum is proportional to the length (in bits) of the bignum and independent 
of the smaller factor.)
     
     I see! Interesting.
     
You might then try these:
     
       (defun fac3 (n)
         (labels ((f (a b)
                    (case (- b a)
                      (1 b)
                      (2 (* (- b 1) b))
                      (3 (* (- b 2) (- b 1) b))
                      (4 (* (- b 3) (- b 2) (- b 1) b))
                      (t (let ((m (ash (+ a b) -1))) (* (f a m) (f m b))))
                 )) )
           (if (plusp n) (f 0 n) 1)
       ) )
     
     I suggest that you submit this to the IOLCC (International Obfuscated 
     Lisp Code Contest :-)