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=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID
	autolearn=no autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,d923bb34ea827f56
X-Google-Attributes: gid103376,public
From: "Sam Harbaugh (at Home)" <harbaugh@ACUSYS.COM>
Subject: Re: Ada / Boeing 777
Date: 1996/03/23
Message-ID: <199603231303.IAA28759@bb.iu.net>#1/1
X-Deja-AN: 143847335
sender: Ada programming language <INFO-ADA@VM1.NoDak.EDU>
x-sender: harbaugh@iu.net
comments: Gated by NETNEWS@AUVM.AMERICAN.EDU
content-type: text/plain; charset="us-ascii"
mime-version: 1.0
newsgroups: comp.lang.ada
x-mailer: Windows Eudora Light Version 1.5.2
Date: 1996-03-23T00:00:00+00:00
List-Id: <comp.lang.ada>

 Matt Kennel <mbk@CAFFEINE.ENGR.UTK.EDU>wrote:
>The representation (aka implementation) of angle is wrong.

>It should be a complex number of unit magnitude.  Rotations in any
>direction can be implemented as complex multiplication without any
>discontinuities, wrap around errors or problems at 0 or 180 or 360
>degrees.

>This is an easy 2-d representation of the rotation group.  3-d is
>trickier: either Euler angles or quaternions.

I agree with Matt. In my posting I assumed that the Airbus software used
better than one degree integer heading values and that the original poster
was simplifying it to make his point clearer. The point of my post was to
call attention to the possible absence of domain expertise in and around the
software development activity.

I have boxes of simulator code, F4, V22, etc. and without looking I recall
that all of them use quaternions.

>
See, sometimes physicists *can* be useful.  ;-)

Yes Matt, I agree. Where would we engineers be without the understanding of
nature that the physicists provide.  (serious, no smiley).

sam harbaugh  harbaugh@acusys.com