On Tue, Apr 9, 2013 at 3:30 PM, Pierpaolo Bernardi <olopie...@gmail.com>wrote:
while the for version should be almost all big x big.
>
oops, no. The for version should be almost all fix x big.
Here's a count considering also the type of the result of the
multiplication:
> (fact 1000000)
#hash(((fix fix -> fix) . 437071)
((big big -> big) . 209717)
((fix big -> big) . 46338)
((fix fix fix -> fix) . 48577)
((fix fix -> big) . 209718))
====
(define x*-counter 'not-initialized)
(define (x* . args)
(define (classify x)
(if (fixnum? x)
'fix
'big))
(define res (apply * args))
(hash-update! x*-counter
(append (map classify args)
'(->)
(list (classify res)))
add1
0)
(apply * args))
;; from included; to excluded.
(define (mult from to)
(case (- to from)
((0) 1)
((1) from)
((2) (x* from (+ from 1)))
((3) (x* from (+ from 1) (+ from 2)))
;; ...
(else
(let ((middle (quotient (+ from to) 2)))
(x* (mult from middle) (mult middle to))))))
(define (fact n)
(set! x*-counter (make-hash))
(define f (if (zero? n)
1
(mult 2 (add1 n))))
(values ;f
x*-counter))
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