www.delorie.com/archives/browse.cgi   search  
Mail Archives: djgpp/2001/07/04/13:33:50

Date: Wed, 04 Jul 2001 20:30:20 +0300
From: "Eli Zaretskii" <eliz AT is DOT elta DOT co DOT il>
Sender: halo1 AT zahav DOT net DOT il
To: djgpp AT delorie DOT com
Message-Id: <2950-Wed04Jul2001203020+0300-eliz@is.elta.co.il>
X-Mailer: Emacs 20.6 (via feedmail 8.3.emacs20_6 I) and Blat ver 1.8.9
In-reply-to: <3b4348be.81254401@news.primus.ca> (invalid@erehwon.invalid)
Subject: Re: DJGPP reserves wrong int size
References: <9dde68b7 DOT 0106241053 DOT 2a385311 AT posting DOT google DOT com> <200106242138 DOT RAA18013 AT envy DOT delorie DOT com> <3b37e92e DOT 288745911 AT news DOT primus DOT ca> <200106260242 DOT WAA00615 AT envy DOT delorie DOT com> <3b3b4e40 DOT 213415946 AT news DOT primus DOT ca> <6480-Fri29Jun2001102012+0300-eliz AT is DOT elta DOT co DOT il> <3b3d95b2 DOT 362800381 AT news DOT primus DOT ca> <7704-Sat30Jun2001163109+0300-eliz AT is DOT elta DOT co DOT il> <3b4348be DOT 81254401 AT news DOT primus DOT ca>
Reply-To: djgpp AT delorie DOT com
Errors-To: nobody AT delorie DOT com
X-Mailing-List: djgpp AT delorie DOT com
X-Unsubscribes-To: listserv AT delorie DOT com

> From: invalid AT erehwon DOT invalid (Graaagh the Mighty)
> Newsgroups: comp.os.msdos.djgpp
> Date: Wed, 04 Jul 2001 16:51:18 GMT
> 
> On Sat, 30 Jun 2001 16:31:09 +0300, "Eli Zaretskii"
> <eliz AT is DOT elta DOT co DOT il> sat on a tribble, which squeaked:
> 
> >Yes, I understand.  And that precisely is the sign of a numerical bug,
> >in most cases I've seen.
> 
> I would think if the problem was numerical instability of the
> algorithm, the problem would be *more* pronounced when using a *lower*
> precision.

This is true for some numerical computations, but not for all of
them.

> >Numerical computations are tricky.
> 
> These ones aren't. They just add and multiply and subtract and
> compare, and they only compare for exceeding certain (small)
> magnitudes -- they don't depend on an exact comparison with anything,
> ever.

In any decent course in numerical computation, the first lesson
teaches you that you cannot even solve a quadratic equation without
risking numerical pitfalls.

- Raw text -


  webmaster     delorie software   privacy  
  Copyright © 2019   by DJ Delorie     Updated Jul 2019