GNU bug report logs - #13031
large numbers

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From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Mark H Weaver <mhw <at> netris.org>
Cc: tracker <at> debbugs.gnu.org
Subject: bug#13031: closed (large numbers)
Date: Fri, 07 Dec 2012 17:08:02 +0000

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Your message dated Fri, 07 Dec 2012 12:06:41 -0500
with message-id <874njxbxlq.fsf <at> tines.lan>
and subject line Re: bug#13031: large numbers
has caused the debbugs.gnu.org bug report #13031,
regarding large numbers
to be marked as done.

(If you believe you have received this mail in error, please contact
help-debbugs <at> gnu.org.)


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13031: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=13031
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From: Jozef Chraplewski <jozef <at> applicake.com>
To: bug-guile <at> gnu.org
Subject: large numbers
Date: Thu, 29 Nov 2012 09:42:09 +0100

Hi,

It looks that guile returns incorrect results when it works with really big numbers.

I've found it during resolving problem 48 from Project Euler:

http://projecteuler.net/problem=48

The solution is trivial:

(define (problem-48 limit)
 (define (F)
   (let loop ((n 1)
              (sum 0))
     (if (<= n limit)
         (loop (+ n 1) (+ sum (expt n n)))
         sum)))

 (let* ((str (number->string (F)))
          (len (string-length str)))
   (substring str (- len 10) len)))

(display (problem-48 1000))
(newline)


The proper answer is 9110846700 but guile returns 6457854188

I've tested solution under other scheme implementations (MIT scheme, petite and mzscheme) and it works as it should.

Does such a big numbers in guile require any special treatment or just they are not supported?

Best,
Jozef

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From: Mark H Weaver <mhw <at> netris.org>
To: Jozef Chraplewski <jozef <at> applicake.com>
Cc: 13031-done <at> debbugs.gnu.org
Subject: Re: bug#13031: large numbers
Date: Fri, 07 Dec 2012 12:06:41 -0500

Hi Jozef,

Jozef Chraplewski <jozef <at> applicake.com> writes:
> Yes, I use 64-bit machine and (* (expt 2 32) (expt 2 32)) produces 0 (without the patch).
>
> I've applied your fix and it works perfectly.

Excellent!  Thanks for bringing this problem to our attention,
and for helping us track it down :)

> I suppose that you will add the patch to the next stable version (2.0.8 ??)

Yes.

   Thanks again,
       Mark

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