From: Dave Berry <dave@kal.com>
To: Pierre Weis <Pierre.Weis@inria.fr>
Subject: RE: Undefined evaluation order
Date: Fri, 13 Oct 2000 14:56:50 +0100 [thread overview]
Message-ID: <3145774E67D8D111BE6E00C0DF418B6631EE94@nt.kal.com> (raw)
David,
Thanks for your reply. Are you saying that if (a * b) would result in a NaN
then you always want (a * b * 0.0) to return a NaN, so that you are aware of
the potential problem?
Dave.
> -----Original Message-----
> From: David McClain [mailto:dmcclain@azstarnet.com]
> Sent: Thursday, October 12, 2000 6:06 PM
> To: caml-list@inria.fr
> Subject: Re: Undefined evaluation order
>
>
> ... but the same would be true the other way too... (0.0 * a * b). I am a
> numeric programmer and these things are unavoidable no matter how you
choose
> to order the evaluations.
>
> If (a * b) raises a NaN then what would be the value of 0.0 times that?
The
> IEEE spec would say the result would have to continue to be a NaN.
>
> I normally perform all arithmetic with exception processing supressed or
> deferred. The only time an exception is useful to me is if there is some
> remedial action that could be taken. I want my NaN's and INF's to appear
in
> my answers. In particular, if something should go awry at one point out of
> millions I don't want that one point to hose my entire calculation. (Note
> that I do not look kindly at the Fortran way of aborting an entire program
> for one bad point...) In signal and image processing, especially in a
> real-time environment, you just drop the bad points on the floor and
> continue running.
>
> - DM
next reply other threads:[~2000-10-13 14:05 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2000-10-13 13:56 Dave Berry [this message]
-- strict thread matches above, loose matches on Subject: below --
2000-10-20 14:59 Gerard Huet
2000-10-14 1:42 David McClain
2000-10-12 17:06 David McClain
2000-10-12 11:32 Greg Morrisett
2000-10-12 9:53 Dave Berry
2000-10-11 12:22 Greg Morrisett
2000-10-11 20:35 ` Pierre Weis
2000-10-13 7:05 ` Judicael Courant
2000-10-13 14:21 ` Markus Mottl
2000-10-16 8:38 ` Christophe Raffalli
2000-10-16 15:48 ` Brian Rogoff
2000-10-16 16:29 ` Christophe Raffalli
2000-10-17 9:19 ` Ralf Treinen
2000-10-10 19:23 David McClain
2000-10-10 18:55 John R Harrison
2000-10-10 12:46 Greg Morrisett
2000-10-05 18:14 Brian Rogoff
2000-10-06 2:02 ` Ken Wakita
2000-10-06 11:18 ` Pierpaolo BERNARDI
2000-10-07 6:46 ` Ken Wakita
2000-10-08 15:43 ` David Mentré
2000-10-08 22:47 ` Brian Rogoff
2000-10-10 12:47 ` Thorsten Ohl
2000-10-10 20:52 ` Brian Rogoff
2000-10-10 19:26 ` Stefan Monnier
2000-10-09 12:45 ` Xavier Leroy
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