From: R_Tim_Coslet@cup.portal.com
Subject: Re: Types with physical dimension
Date: Thu, 29 Sep 94 19:06:39 PDT
Date: 1994-09-29T19:06:39-07:00 [thread overview]
Message-ID: <123813@cup.portal.com> (raw)
In-Reply-To: 36bss8$79@gnat.cs.nyu.edu
>"What do Ada programmers do to guard against dimensional errors"
>
>Probably not much, because in practice, at least in my experience, such
>errors are rare, although they are an obvious target for theoretical
>discussions.
When is 0 multiplied by 0 equal to 4 million?
When a programmer dropped an equation from a data sheet directly
into the code, without thinking that the equation used units of volts
but the A/D converter supplying the numbers has some "arbitrary"
unit scaling and is offset binary instead of twos complement.
Example:
0V = 2048 A/D converter units.
Therfore 0V * 0V = about 4 million.
Admitedly not directly related to the current subject, but does
illustrate a case of a problem with processing real world physical
data without thinking the units and scaling thru...
At least Ada reported constraint errors instead of just scrambling the
result and giving a totally inexplicable wrong answer like Certain
other languages would :-)
R. Tim Coslet
Usenet: R_Tim_Coslet@cup.portal.com
technology, n. domesticated natural phenomena
next prev parent reply other threads:[~1994-09-30 2:06 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
1994-09-27 22:18 Types with physical dimension Paul Graham
1994-09-28 13:59 ` Robert Dewar
1994-09-30 2:06 ` R_Tim_Coslet [this message]
1994-10-03 17:31 ` Stephen A. Leake
1994-10-04 11:51 ` Robert I. Eachus
1994-10-04 19:45 ` Mark A Biggar
[not found] ` <CxBBx8.7L@irvine.com>
1994-10-13 22:15 ` gamache
1994-10-12 3:43 ` Matt Kennel
1994-10-04 14:56 ` Robert Dewar
1994-10-05 14:53 ` Bob Gilbert
1994-10-05 8:38 ` Jean-Pierre Rosen
1994-10-05 10:35 ` Stephen J Bevan
1994-10-05 13:17 ` Jean-Pierre Rosen
1994-10-05 15:48 ` Norman H. Cohen
-- strict thread matches above, loose matches on Subject: below --
1994-09-28 10:55 Simtel20 Transfer
1994-09-28 18:56 ` Mark A Biggar
1994-10-04 2:06 ` lmiller
[not found] <GRAHAM.94Sep27181841@canopus.clsi.com>
1994-09-28 17:36 ` William Brennan
1994-09-28 21:41 ` Tucker Taft
1994-09-29 4:11 ` Robert Dewar
1994-09-29 11:19 ` Peter Hermann
1994-09-30 10:17 ` Dr John Stockton
1994-10-03 4:37 ` Robert Dewar
1994-09-29 13:37 ` Tucker Taft
1994-10-03 4:40 ` Robert Dewar
1994-09-28 19:28 Paul Pukite
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