From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham
	autolearn_force=no version=3.4.4
X-Google-Thread: 103376,c9d5fc258548b22a
X-Google-NewGroupId: yes
X-Google-Attributes: gida07f3367d7,domainid0,public,usenet
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news1.google.com!news3.google.com!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail
From: Bill Findlay <news@findlayw.plus.com>
Newsgroups: comp.lang.ada
Subject: Re: How do I write directly to a memory address?
Date: Tue, 08 Feb 2011 00:21:37 +0000
Message-ID: <C9763D11.5BD0%news@findlayw.plus.com>
References: 
 <67063a5b-f588-45ea-bf22-ca4ba0196ee6@l11g2000yqb.googlegroups.com>
 <31c357bd-c8dc-4583-a454-86d9c579e5f4@m13g2000yqb.googlegroups.com>
 <05a3673e-fb97-449c-94ed-1139eb085c32@x1g2000yqb.googlegroups.com>
 <iimmvm$tsp$1@news.eternal-september.org> <8r86vgFc3uU1@mid.individual.net>
 <iimrem$udn$1@news.eternal-september.org>
 <19fh1chm74f9.11cws0j5bckze.dlg@40tude.net>
 <5d9bd120-4953-4fb1-a890-27267245e954@8g2000prt.googlegroups.com>
 <883b7161-15ee-4874-95bb-2e0273dab51d@y36g2000pra.googlegroups.com>
 <8r9iboFkfvU1@mid.individual.net>
 <14246472-9488-488a-8720-77b85b91707c@d23g2000prj.googlegroups.com>
 <8r9ouqFselU1@mid.individual.net> <iioon1$agg$1@news.eternal-september.org>
 <iiopbr$bs7$1@news.eternal-september.org> <iippmb$q45$1@munin.nbi.dk>
Mime-Version: 1.0
Content-Type: text/plain;
	charset="US-ASCII"
Content-Transfer-Encoding: 7bit
X-Trace: individual.net wxXuTQv4/ZhokwpgEQ+3zAhrTpLp4KvJbhrBJ9cZGKy3xKkPNn
Cancel-Lock: sha1:Gh8Yy7LkCuDRTftJBUYpFZ5EthQ=
User-Agent: Microsoft-Entourage/12.28.0.101117
Thread-Topic: How do I write directly to a memory address?
Thread-Index: AcvHJiX5KMAb0cprLU+MudTVzgqjAA==
Xref: g2news1.google.com comp.lang.ada:16958
Date: 2011-02-08T00:21:37+00:00
List-Id: <comp.lang.ada>

On 07/02/2011 21:54, in article iippmb$q45$1@munin.nbi.dk, "Randy Brukardt"
<randy@rrsoftware.com> wrote:

> I remember hearing this story in college. And it supposely was old then.
> I've always thought of it as a sort of urban legend.

I had to debug a FORTRAN 66 program (my own, sadly, written in 1967) that
was going astray in a statement of the form:

      IF (X) 101, 102, 103

The problem was that a previous call to a library subroutine, along the
lines of:

      CALL SOLVE(A, X, B, 0.0)

was updating the accuracy parameter 0.0 to the residual norm of the solution
(or some such accuracy indication), and this was making the implicit
comparison with 0.0 in the later IF statement go wrong.

-- 
Bill Findlay
with blueyonder.co.uk;
use  surname & forename;