Re: About the F-22 software bug

[Martin <martin.dowie@btopenworld.com>]

On Feb 5, 6:42 am, Dennis Lee Bieber <wlfr...@ix.netcom.com> wrote:
> On Thu, 04 Feb 2010 19:46:15 +0100, Pascal Obry <pas...@obry.net>
> declaimed the following in comp.lang.ada:
>
> > I know that the F-22 is 90% of Ada. Is there some public information
> > about this bug? Is that a design bug?
>
>         So far as I recall -- from some years ago -- it was an algorithm
> problem handling position information wrap-around from crossing, as
> mentioned, the International Dateline... -180.0 to +180.0 deg longitude.
>
>         I didn't hear that they had to follow the tankers back -- was under
> the impression once they managed to cross back heading east a reboot of
> the navigation system started working again...
>
> --
>         Wulfraed         Dennis Lee Bieber               KD6MOG
>         wlfr...@ix.netcom.com HTTP://wlfraed.home.netcom.com/

For some reason (that I don't get at all) lots of systems define long
as -180 <= x <= +180 degrees.

Having the potential to alias a position seems like a bad idea for a
start, so when I've been coding such systems up, I've always spent a
bit of time making it convert positions into the range -180 <= x <
+180 degrees and using a proper ADT.

I wonder if it was anything to do with that?...

Cheers
-- Martin