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From: =?ISO-8859-1?Q?SZUCS_G=E1bor?= <surrano@mailbox.hu>
To: <pgsql-sql@postgresql.org>
References: 
 <072c01c39d65$65f83950$0403a8c0@fejleszt4><20031028154536.GA29427@it.is.rice.edu><074b01c39d72$6f512f90$0403a8c0@fejleszt4>
	<87brs1gr4y.fsf@stark.dyndns.tv>
Subject: Re: numeric and float converts to int differently?
Date: Tue, 28 Oct 2003 21:16:53 +0100
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----- Original Message ----- 
From: "Greg Stark" <gsstark@mit.edu>
Sent: Tuesday, October 28, 2003 7:21 PM


> > > cannot see is that the float values are not actually exactly 0.5
> >
> > Yes I could guess that (floating point vs fixed), but is this a
coincidence
> > that both '0.5'::float and '-0.5'::float are closer to 0, whereas they
could
> > be closer to +/-1, as well as both closer to the lower or upper bound.
>
> Wouldn't 0.5 and -0.5 be representable exactly as floats?

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.

G.
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