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Re: [HACKERS] [PATCHES] [BUGS] BUG #2846: inconsistent and

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Roman Kononov <kononov195-pgsql(at)yahoo(dot)com>
Cc: pgsql-hackers(at)postgresql(dot)org, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, PostgreSQL-patches <pgsql-patches(at)postgresql(dot)org>
Subject: Re: [HACKERS] [PATCHES] [BUGS] BUG #2846: inconsistent and
Date: 2007-01-19 13:56:48
Message-ID: 200701191356.l0JDumS04847@momjian.us (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-patches
Roman Kononov wrote:
> On 12/27/2006 01:15 PM, Tom Lane wrote:
> > I'm not convinced that you're fixing things so much as doing your best
> > to destroy IEEE-compliant float arithmetic behavior.
> > 
> > I think what we should probably consider is removing CheckFloat4Val
> > and CheckFloat8Val altogether, and just letting the float arithmetic
> > have its head.  Most modern hardware gets float arithmetic right per
> > spec, and we shouldn't be second-guessing it.
> 
> I vote for complete IEEE-compliance. No exceptions with pure floating
> point math. Float -> int conversions should reject overflow, INF and
> NaN. Float -> numeric conversions should reject INF.

I think we did that in current CVS.  Feel free to download a snapshot
from the ftp server and try it out.

> > A slightly less radical proposal is to reject only the case where
> > isinf(result) and neither input isinf(); and perhaps likewise with
> > respect to NaNs.
> 
> This might look like another possibility for confusion. For example
> INF-INF=NaN.

Yep, that's what we get now.

-- 
  Bruce Momjian   bruce(at)momjian(dot)us
  EnterpriseDB    http://www.enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +

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