GNU bug report logs - #13031
large numbers

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From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Jozef Chraplewski <jozef <at> applicake.com>
Subject: bug#13031: closed (Re: bug#13031: large numbers)
Date: Fri, 07 Dec 2012 17:08:02 +0000

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Your bug report

#13031: large numbers

which was filed against the guile package, has been closed.

The explanation is attached below, along with your original report.
If you require more details, please reply to 13031 <at> debbugs.gnu.org.

-- 
13031: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=13031
GNU Bug Tracking System
Contact help-debbugs <at> gnu.org with problems

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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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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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