From: Christopher Browne <cbbrowne@libertyrms.info>
Subject: Re: numeric and float converts to int differently?
Date: Tue, 28 Oct 2003 18:11:13 -0500
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surrano@mailbox.hu (SZUCS Gábor) writes:
> As Tom pointed out, it isn't a floating point failure -- it is how rounding
> float is implemented. I assume anything with less than 15 digits can be
> exactly represented as float.

No, "decimal" fractions cannot ever be exactly represented in floating
point because since they use powers of two, you wind up with repeated
fractions.

1/3 is approximately 0.3333333, but you cannot present that exactly in
decimal.

In the very same way, 1/10 is approximately equal to
0.001001001001001001001001001001 (as a binary 'fraction'); the '001'
part is a repeating group, and wherever you terminate it, you lose
exactness.
-- 
(reverse (concatenate 'string "ofni.smrytrebil" "@" "enworbbc"))
<http://dev6.int.libertyrms.com/>
Christopher Browne
(416) 646 3304 x124 (land)