Re: Programming language and IDE design

From	Jonathan Thornburg <jonathan@cobalt.astro.indiana.edu>
Newsgroups	comp.compilers
Subject	Re: Programming language and IDE design
Date	2013-11-19 19:39 +0000
Organization	Compilers Central
Message-ID	<13-11-023@comp.compilers> (permalink)
References	<13-11-016@comp.compilers>

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I asked:
> at what point should floating-point arithmetic overflow
> or underflow, and what should be the consequences of this happening?
> To be very precise, what "single semantically valid meaning" should we
> perscribe for trying to compute the square of 1.0e300?

Martin Ward <martin@gkc.org.uk> wrote:
> These questions are precisely why the IEEE 754 floating point standard
> was needed:  it specifies precise answers to all these questions
> (without leaving anything "implementation dependent",
> other than extra information encoded in a NaN).  See the paper
> "What Every Computer Scientist Should Know About Floating Point":
>
> http://www.validlab.com/goldberg/paper.ps

The IEEE single-extended and double-extended formats define the
precision and exponent range as "implementation-dependent".  You can
see this in table D-1 of the validlab.com version of Goldberg's paper
[which we should note was originally published in ACM Computing Surveys
23(1), March 1991, pages 5-48], and the immediately following sentence
   "The IEEE standard only specifies a lower bound on how many
    extra bits extended precision provides."
This means that whether or not certain operations overflow is indeed
implementation-dependent.

--
-- "Jonathan Thornburg [remove -animal to reply]" <jthorn@astro.indiana-zebra.edu>
   Dept of Astronomy & IUCSS, Indiana University, Bloomington, Indiana, USA
   "There was of course no way of knowing whether you were being watched
    at any given moment.  How often, or on what system, the Thought Police
    plugged in on any individual wire was guesswork.  It was even conceivable
    that they watched everybody all the time."  -- George Orwell, "1984"

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Re: Programming language and IDE design Martin Ward <martin@gkc.org.uk> - 2013-11-16 15:55 +0000
  Re: Programming language and IDE design Hans-Peter Diettrich <DrDiettrich1@aol.com> - 2013-11-16 19:48 +0100
  Re: Programming language and IDE design George Neuner <gneuner2@comcast.net> - 2013-11-18 19:02 -0500
    Re: Programming language and IDE design "Steven G. Kargl" <sgk@REMOVEtroutmask.apl.washington.edu> - 2013-11-19 15:36 +0000
    Re: Programming language and IDE design George Neuner <gneuner2@comcast.net> - 2013-11-19 12:41 -0500
      Re: Parsing Fortran, was Programming language and IDE design glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2013-11-19 20:18 +0000
        Re: Parsing Fortran, was Programming language and IDE design glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2013-11-21 21:22 +0000
    Re: Programming language and IDE design wclodius@earthlink.net (William Clodius) - 2013-11-22 18:27 -0700
    Re: Programming language and IDE design "robin" <robin51@dodo.com.au> - 2013-11-25 10:33 +1100
      Re: Programming language and IDE design Martin Ward <martin@gkc.org.uk> - 2013-12-03 15:15 +0000
        Re: Programming language and IDE design Hans-Peter Diettrich <DrDiettrich1@aol.com> - 2013-12-05 03:35 +0100
    Re: Programming language and IDE design hu47121@usenet.kitty.sub.org (Hannah) - 2014-03-02 00:03 +0000
      Re: LL vs LR, was Programming language and IDE design Ivan Godard <ivan@ootbcomp.com> - 2014-03-01 20:31 -0800
        Re: LL vs LR, was Programming language and IDE design Kaz Kylheku <kaz@kylheku.com> - 2014-03-02 18:41 +0000
      Re: Programming language and IDE design George Neuner <gneuner2@comcast.net> - 2014-03-02 12:21 -0500
  Re: Programming language and IDE design Jonathan Thornburg <jonathan@cobalt.astro.indiana.edu> - 2013-11-19 19:39 +0000

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