From: robin <robin_v@nospam.bigpond.com>
Subject: Re: Fortran or Ada?
Date: 1998/10/05
Date: 1998-10-05T00:00:00+00:00 [thread overview]
Message-ID: <3618299b.0@139.134.5.33> (raw)
Niklas Holsti <nholsti@icon.fi> writes: > Toon Moene wrote:
> >
> > In my mind, an exception is a sign that the assumptions behind the
> > (physics/mathematics) of your model is wrong, and - even though that pertains
> > to a large extent also to rocket ascent - this would not lead to a reasonably
> > safe procedure here.
>
> Yes, this is one category of exceptions (the other category is where
> exception handling is used to catch rare but foreseeable situations,
> such
> as errors in input data files -- END= and ERR= labels, for example).
>
> It seems that the designers of the Ariane 4 guidance system had this
> view, except that their "model" included the processing hardware in
> addition to the models encoded in the software. To decide how to handle
> the overflow exception, they had to guess which part of their model was
> at fault -- whether the hardware or the software was wrong.
No guessing was involved. Any kind of interrupt is treated
as a hardware error.
This was the fundamental flaw in their assumptions.
> They guessed
> "hardware error". In the context of Ariane 4, it hasn't been shown that
> this was the wrong thing to do.
The Report criticized the assumption [that sofware errors couldn't
happen].
> The odds in this guess must depend on how well the software models were
> verified and validated. I haven't seen any claims that the software
> models were not correct for Ariane 4.
>
> Niklas Holsti
> Space Systems Finland Ltd
> (This comment expresses personal opinion and not Space Systems Finland
> policy.)
next reply other threads:[~1998-10-05 0:00 UTC|newest]
Thread overview: 93+ messages / expand[flat|nested] mbox.gz Atom feed top
1998-10-05 0:00 robin [this message]
-- strict thread matches above, loose matches on Subject: below --
1998-10-05 0:00 Fortran or Ada? Robert I. Eachus
1998-10-05 0:00 Condic, Marin D.
1998-09-24 0:00 Walt Brainerd
1998-09-25 0:00 ` Robert I. Eachus
1998-09-25 0:00 ` dewarr
1998-09-23 0:00 Marin David Condic, 561.796.8997, M/S 731-96
1998-09-23 0:00 ` Gisle S{lensminde
1998-09-24 0:00 ` John McCabe
1998-09-24 0:00 ` Gisle S{lensminde
1998-09-24 0:00 ` Dean F. Sutherland
1998-09-24 0:00 ` Samuel T. Harris
1998-09-23 0:00 Marin David Condic, 561.796.8997, M/S 731-96
[not found] <36068E73.F0398C54@meca.polymtl.ca>
1998-09-22 0:00 ` Gisle S{lensminde
1998-09-22 0:00 ` Jeff Templon
1998-09-22 0:00 ` Rakesh Malhotra
1998-09-22 0:00 ` Corey Minyard
1998-09-22 0:00 ` Larry Kilgallen
1998-09-22 0:00 ` dewarr
1998-09-23 0:00 ` Jeff Templon
1998-09-23 0:00 ` Corey Minyard
1998-09-24 0:00 ` Joel Seidman
1998-09-24 0:00 ` Craig Burley
1998-09-25 0:00 ` dewarr
1998-09-25 0:00 ` Jonathan Guthrie
1998-09-26 0:00 ` Craig Burley
1998-09-26 0:00 ` dewarr
1998-09-26 0:00 ` Craig Burley
1998-09-26 0:00 ` Robert B. Love
1998-09-24 0:00 ` Marc A. Criley
1998-09-24 0:00 ` Jeff Templon
1998-09-25 0:00 ` Dale Stanbrough
1998-09-30 0:00 ` Daniel Barker
1998-09-30 0:00 ` Lawrence Kirby
1998-10-01 0:00 ` Aaron Crane
1998-10-05 0:00 ` Terry Devine
1998-09-25 0:00 ` dewarr
1998-09-24 0:00 ` dewarr
1998-09-24 0:00 ` Robert I. Eachus
1998-09-24 0:00 ` William Clodius
1998-09-25 0:00 ` dewarr
1998-09-25 0:00 ` dewarr
1998-09-25 0:00 ` Robert I. Eachus
1998-09-25 0:00 ` dewarr
1998-09-25 0:00 ` jbs
1998-09-26 0:00 ` dewarr
1998-09-28 0:00 ` jbs
1998-09-29 0:00 ` Dean F. Sutherland
1998-09-29 0:00 ` William B. Clodius
1998-09-30 0:00 ` jbs
1998-09-30 0:00 ` William Clodius
1998-09-30 0:00 ` dewarr
1998-09-30 0:00 ` jbs
1998-09-30 0:00 ` William Clodius
1998-10-03 0:00 ` Niklas Holsti
1998-10-03 0:00 ` Toon Moene
1998-10-03 0:00 ` Niklas Holsti
1998-10-03 0:00 ` Toon Moene
1998-10-04 0:00 ` Niklas Holsti
1998-10-05 0:00 ` Michel OLAGNON
1998-10-05 0:00 ` Ian St. John
1998-10-05 0:00 ` Richard D Riehle
1998-10-05 0:00 ` dewarr
1998-10-05 0:00 ` dewarr
1998-10-05 0:00 ` Ian St. John
1998-10-06 0:00 ` dewarr
1998-10-06 0:00 ` James Giles
1998-10-06 0:00 ` Mark A Biggar
1998-10-06 0:00 ` James Giles
1998-10-07 0:00 ` dewarr
1998-10-07 0:00 ` dewarr
1998-10-06 0:00 ` Toon Moene
1998-10-06 0:00 ` Jonathan Guthrie
1998-10-06 0:00 ` Ian St. John
1998-10-08 0:00 ` Gary L. Scott
1998-10-06 0:00 ` Michel OLAGNON
1998-10-07 0:00 ` Ian St. John
1998-09-29 0:00 ` Gautier.DeMontmollin
1998-09-29 0:00 ` Dean F. Sutherland
1998-09-29 0:00 ` Dean F. Sutherland
1998-10-02 0:00 ` Geoff Bull
1998-10-02 0:00 ` Robert I. Eachus
1998-10-02 0:00 ` jbs
1998-10-02 0:00 ` William Clodius
1998-10-03 0:00 ` jbs
1998-10-03 0:00 ` Larry Elmore
1998-10-06 0:00 ` Robert I. Eachus
1998-10-06 0:00 ` Pat Rogers
[not found] ` <6udre0$ha1$1@nnrp1.dejane <6utg60$h6l$1@nnrp1.dejanews.com>
1998-10-01 0:00 ` robin_v
1998-09-23 0:00 ` Frank Ecke
1998-09-23 0:00 ` bglbv
1998-09-23 0:00 ` Robert I. Eachus
1998-09-24 0:00 ` Richard D Riehle
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