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Re: Avoiding roundoff errors in calculations?

• To: Jonathan Borden <jonathan@o...>
• Subject: Re: Avoiding roundoff errors in calculations?
• From: John Cowan <jcowan@r...>
• Date: Fri, 29 Aug 2003 17:33:15 -0400
• Cc: xml-dev@l...
• In-reply-to: <3F4FC31A.5070500@o...>
• References: <3F4FA206.5E2367A2@m...> <3F4FC31A.5070500@o...>
• User-agent: Mutt/1.4.1i

Jonathan Borden scripsit:

> to be practical, if your measurement error is much greater than the 
> possible roundoff error you are ok. if you need to completely avoid 
> roundoff error, then you generally convert the problem to integer (e.g. 
> bigint) and deal with the radii (plural of radix?) and moduli. then 
> there's the lispish way of dealing with this problem, which is to return 
> a formulaic expression that can be evaluated by the client to get the 
> desired result :-)

Common Lisp and Scheme have a fraction datatype, which often does what's
needed in these case.  2 divided by 3 is 2/3, not 0, not 0.666666666666667.

-- 
John Cowan  www.ccil.org/~cowan  www.reutershealth.com  jcowan@r...
All "isms" should be "wasms".   --Abbie

• References:
  • Avoiding roundoff errors in calculations?
    • From: "Roger L. Costello" <costello@m...>
  • Re: Avoiding roundoff errors in calculations?
    • From: Jonathan Borden <jonathan@o...>

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