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From:	"Dave Korn" <dave DOT korn AT artimi DOT com>
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Subject:	RE: strange behavior with perl v 5.8.8
Date:	Thu, 27 Sep 2007 16:46:58 +0100
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On 27 September 2007 16:14, Andrew Louie wrote:

> Hello,
> 
> I've run into a strange adding problem with perl:
> 
> when incrementing by 0.1 

... an infinite, non-repeating fraction in binary floating-point, that can
only be inexactly approximated ... 

> i get a strange behavior where at some
> arbitrary  number, it will append 0.9999999999 to the end of the
> number.

  'fraid so.  Use rounding if you like.

  This is bog-standard floating point behaviour, part of the fundamental
limitations of the representation.  See, e.g.

http://docs.mandragor.org/files/Programming_languages/C/clc_faq_en/C-faq/q14.1
.html

http://en.wikipedia.org/wiki/Floating_point#Accuracy_problems

or in general google for "floating point accuracy".

    cheers,
      DaveK
-- 
Can't think of a witty .sigline today....


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