<html> <head> <style></style></head> <body class='hmmessage'><div dir='ltr'>I think you are right, for some reason i read it as the repetition of a specific number, and not a repetition of any of the numbers already done. <div>> Date: Mon, 27 May 2013 00:36:46 +0200 > Subject: Re: [racket] A problem with Windows 8? > From: olopierpa@gmail.com > To: tomcoiro@hotmail.com > CC: users@racket-lang.org > > I don't see how your function count-times implements the required algorithm. > > Please explain. > > > On Mon, May 27, 2013 at 12:01 AM, Tomás Coiro <tomcoiro@hotmail.com> wrote: > > I'm trying to do this Rosetta Code problem: > > http://rosettacode.org/wiki/Average_loop_length > > > > Now, this is my code > > #lang racket > > (require (only-in math factorial)) > > > > (define (analytical n) > > (apply + > > (build-list n (compose (lambda (x) (/ (factorial n) > > (expt n x) > > (factorial (- n x)))) > > add1)))) > > > > (define (count-times x times) > > (if (= 0 (random x)) > > (add1 times) > > (count-times x (add1 times)))) > > > > (define (test n times) > > (/ > > (for/fold ((count 0)) > > ((i (in-range times))) > > (count-times n count)) > > times)) > > > > (define (test-table max-n times) > > (displayln " n\tavg\ttheory\terror") > > (displayln "-------------------------------") > > (for ((i (in-range 1 (add1 max-n)))) > > (define average (exact->inexact (test i times))) > > (define theory (exact->inexact (analytical i))) > > (define difference (* (sub1 (/ average theory)) 100)) > > (displayln (format "~a\t~a\t~a\t~a%" i average theory difference)))) > > > > (test-table 20 100000) > > > > > > > > Im not really worrying about the formatting of the output now, this is the > > result. > > n avg theory error > > ------------------------------- > > 1 1.0 1.0 0.0% > > 2 2.00036 1.5 33.35733333333335% > > 3 3.00578 1.8888888888888888 59.12952941176472% > > 4 4.00412 2.21875 80.46738028169015% > > 5 5.0035 2.5104 99.31086679413636% > > 6 6.00016 2.7746913580246915 116.24603337041157% > > 7 7.01433 3.018138700711438 132.4058201283651% > > 8 7.9905 3.2450180053710937 146.23900350550514% > > 9 8.97363 3.4583157448856556 159.47977749778022% > > 10 10.03618 3.66021568 174.19641019624285% > > 11 10.97729 3.852372050737359 184.94885373023365% > > 12 11.96714 4.036073675098951 196.50449826604333% > > 13 12.96795 4.21234791295252 207.8556251283266% > > 14 13.99396 4.382029424383519 219.34883691404528% > > 15 15.09822 4.545807285147228 232.13506541140143% > > 16 15.97676 4.704258247072678 239.62336166263555% > > 17 16.99324 4.857870820801628 249.8083960412072% > > 18 18.00859 5.007063098992893 259.6637318914995% > > 19 18.941 5.152196200957448 267.62963329075353% > > 20 20.05709 5.2935845860009 278.8942950499325% > > > > > > the average loop length is too long, I'm worrying if the problem is my code > > or if it actually is Windows 8. > > I already got a different result with inexact numbers here: > > http://rosettacode.org/wiki/Percentage_difference_between_images#Racket > > > > My question would be first, is my code wrong? (mainly "count-times") > > If it isn't, do you guys get similar results? Could there be a bug in the > > windows 32-bit installation for Windows 8? > > > > ____________________ > > Racket Users list: > > http://lists.racket-lang.org/users > > </div> </div></body> </html>