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From: Eli Zaretskii <eliz@gnu.org>
To: Paul Eggert <eggert@cs.ucla.edu>
Cc: monnier@iro.umontreal.ca, emacs-devel@gnu.org
Subject: Re: [Emacs-diffs] master 37940b3: min and max now return one of their arguments
Date: Thu, 09 Mar 2017 20:34:29 +0200	[thread overview]
Message-ID: <83innifgei.fsf@gnu.org> (raw)
In-Reply-To: <ca2202d1-fa74-4c07-baa1-029afee63b71@cs.ucla.edu> (message from Paul Eggert on Thu, 9 Mar 2017 09:45:47 -0800)

> Cc: monnier@iro.umontreal.ca, emacs-devel@gnu.org
> From: Paul Eggert <eggert@cs.ucla.edu>
> Date: Thu, 9 Mar 2017 09:45:47 -0800
> 
> > I get
> >
> >    (<= 10000000000000001 1e16) => t
> >
> > in Emacs 25.1 on a 64-bit GNU/Linux host.
> >
> Yes, and that's an example of the opposite. Emacs 25 is inconsistent, 

It doesn't look like inconsistency to me, because I expect these two
numbers to be indistinguishable.  It's basically the same as getting
unstable results from qsort -- this should be expected.

> and this inconsistency leads to weirdnesses, e.g., it's possible for (<= 
> A C) to be nil even though (<= A B C) is t, because the implementation 
> of <= does not compare consistently. Programmers generally do not expect 
> these weirdnesses, and the patches in master remove them by having Emacs 
> use consistent comparisons.

Programmers who know something about FP calculations do expect that,
and won't be surprised.



  reply	other threads:[~2017-03-09 18:34 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20170307012700.3354.30219@vcs0.savannah.gnu.org>
     [not found] ` <20170307012701.1C05D23F1F@vcs0.savannah.gnu.org>
2017-03-07 15:04   ` [Emacs-diffs] master 37940b3: min and max now return one of their arguments Stefan Monnier
2017-03-08  3:04     ` John Wiegley
2017-03-08  6:08     ` Paul Eggert
2017-03-08 15:54       ` Eli Zaretskii
2017-03-08 22:04         ` Paul Eggert
2017-03-09 16:10           ` Eli Zaretskii
2017-03-09 16:25             ` Clément Pit-Claudel
2017-03-09 16:54               ` Eli Zaretskii
2017-03-09 17:09                 ` Clément Pit-Claudel
2017-03-09 17:45             ` Paul Eggert
2017-03-09 18:34               ` Eli Zaretskii [this message]
2017-03-07 19:08   ` Glenn Morris
2017-03-08  4:26     ` Tino Calancha
2017-03-08  5:27     ` Paul Eggert
2017-03-08  7:54       ` Andreas Schwab
2017-03-08  8:29       ` Andreas Schwab
2017-03-08 18:47         ` Paul Eggert
2017-03-08 22:10           ` Andreas Schwab
2017-03-11 14:46       ` Andreas Politz
2017-03-12  1:46         ` Tino Calancha
2017-03-12 23:33           ` Andreas Politz

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