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: 103376,7e8cebf09cf80560
X-Google-NewGroupId: yes
X-Google-Attributes: gida07f3367d7,domainid0,public,usenet
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news2.google.com!news2.google.com!goblin3!goblin.stu.neva.ru!exi-transit.telstra.net!news.telstra.net!exi-spool.telstra.net!exi-reader.telstra.net!not-for-mail
From: "robin" <robin51@dodo.com.au>
Newsgroups: comp.lang.ada
References: 
 <a8387564-0835-467d-a461-60a093c38133@k15g2000prk.googlegroups.com><op.vscizsqqlzeukk@jellix.jlfencey.com>
 <4d80b140$0$43832$c30e37c6@exi-reader.telstra.net><op.vsf7vmtblzeukk@jellix.jlfencey.com>
 <4d810172$0$4954$a8266bb1@postbox2.readnews.com>
 <d6e065fb-7271-42d5-812c-83912c8721a5@n1g2000yqm.googlegroups.com>
Subject: Re: How would Ariane 5 have behaved if overflow checking were not
 turned off?
Date: Sat, 19 Mar 2011 08:14:54 +1100
X-Newsreader: Microsoft Outlook Express 4.72.3110.5
X-MimeOLE: Produced By Microsoft MimeOLE V4.72.3110.3
Message-ID: <4d8475d6$0$43834$c30e37c6@exi-reader.telstra.net>
NNTP-Posting-Host: 123.3.27.205
X-Trace: 1300526550 exi-reader.telstra.net 43834 123.3.27.205:1030
Xref: g2news2.google.com comp.lang.ada:19281
Date: 2011-03-19T08:14:54+11:00
List-Id: <comp.lang.ada>

KK6GM wrote in message ...
>On Mar 16, 11:29 am, Hyman Rosen <hyro...@mail.com> wrote:
>> How about this for the essential flaw: Does it really make
>> sense to create data types in your program that are so closely
>> tied to external factors like rocket speed limits and angles?
>> Why not use data types that could handle the full range of
>> values from the sensor? The approach used seems incredibly
>> brittle, and in fact turned out to be so.

>Here's the alternative, for the Ariane situation.  A float value gets
>converted to a 16-bit integer.  The float value is too big to fit
>(let's say it's 33000).  What 16-bit int will that get converted to?
>-31000?

Would you believe 32767 (with appropriate sign).
That keeps the processor running, and it's slightly less than the
actual value.

>  Some random value?  How does continuing along with bogus data
>make the situation better?

It keeps the processor running, and the mission going.

>  Will the control loops really work OK with
>bogus feedback data?

>If you have determined via thorough analysis that the variable in
>question can only _ever_ have a valid range of e.g. -20000 to 20000,
>and it goes to 33000, what _is_ the right action?

Set it to 32767 with sign.
Alterrnativelty, use floating-point.