From: molagnon@ifremer.fr (Michel OLAGNON)
Subject: Re: Fortran or Ada?
Date: 1998/10/06
Date: 1998-10-06T00:00:00+00:00 [thread overview]
Message-ID: <6vcj6f$ak7$1@ys.ifremer.fr> (raw)
In-Reply-To: 3618dc33.0@news.passport.ca
In article <3618dc33.0@news.passport.ca>, "Ian St. John" <istjohn@high-sense.com> writes:
>
>Michel OLAGNON wrote in message <6v9s4t$egn$1@ys.ifremer.fr>...
>>In article <3617AA49.340A5899@icon.fi>, Niklas Holsti <nholsti@icon.fi>
>writes:
><snip>
>>>
>>At the time of writing the software, it might not have been wrong.
>>But later on, the launch procedure was changed for Ariane 4, and
>>the computation no longer needed. IMHO, not removing unnecessary
>>computations that may have side effects IS a "software error".
>>
>>The designers failed, IMHO, to note that even if hardware might
>>be more likely to be wrong than software at time T0, over the whole
>>expected service life of the system, it was software that had the highest
>>probability to end up wrong.
>>
>
>
>IMHO, well tested software doesn't fail.
But, IMHO, such well tested software doesn't exist.
> Hardware does. At least, in the
>sense of random errors. Software can have systematic errors, or design
>limitations. Random errors and unexpected data indicate hardware problems.
>
>The problem in the Ariane 5 case, were that there was no proper review of
>whether the software testing was *valid* for Ariane 5.
The point, IMHO, is that the software was *useless* for Ariane 5, recognized
so by the reviewers, and yet kept because of ``commonality reasons'', which,
IMHO again, is a polite way to say ``lack of thought''. Although I could not
make it out again clearly from the report, I remember that the launch
procedure was changed at some time for Ariane 4, and that the software
was also *useless* for it, but was kept for a similar reason: If it
ain't broken, why change it ?
> This was a
>*management* issue, not a technology issue. If the Ariane 4 had reported
>such values ( causing overflow ) it *would* have been a hardware error.
This is pure speculation. It might have been a software error or a hardware
error, no one can tell. But even if it had been a hardware error, my experience
is that it would be very likely to have happenned *after* T-5 seconds rather
than before (hardware errors happen with vibrations, heat, ...), i.e. at a
time when the computations were no longer needed, that is, IMHO, when the
software error of making useless computations had already happenned.
> This
>was taken into the design, and is correct as such.
>
>The software was *correct* for the mission it was designed for ( Arianne
>4 ). You cannot expect software re-use without evaluation of the
>interface/inputs.
>
>Nor can you design software with the viewpoint that it *might* be used in
>the first warp drive spaceship. KISS, and stick to reality.
>
>
Michel
--
| Michel OLAGNON email : Michel.Olagnon@ifremer.fr|
| IFREMER: Institut Francais de Recherches pour l'Exploitation de la Mer|
| Centre de Brest - B.P. 70 phone : +33-2-9822 4144|
| F-29280 PLOUZANE - FRANCE fax : +33-2-9822 4650|
| http://www.ifremer.fr/ditigo/molagnon/molagnon.html |
next prev parent reply other threads:[~1998-10-06 0:00 UTC|newest]
Thread overview: 96+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <36068E73.F0398C54@meca.polymtl.ca>
1998-09-22 0:00 ` Fortran or Ada? Gisle S{lensminde
1998-09-22 0:00 ` Jeff Templon
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 ` 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 ` Gautier.DeMontmollin
1998-09-29 0:00 ` Dean F. Sutherland
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 ` dewarr
1998-09-30 0:00 ` jbs
1998-09-30 0:00 ` William Clodius
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 ` Ian St. John
1998-10-08 0:00 ` Offtopic Airport Diversion (Was: Fortran or Ada?) Harold Stevens ** PLEASE SEE SIG **
1998-10-08 0:00 ` Ian St. John
1998-10-08 0:00 ` Fortran or Ada? Gary L. Scott
1998-10-06 0:00 ` Toon Moene
1998-10-06 0:00 ` Jonathan Guthrie
1998-10-06 0:00 ` Michel OLAGNON [this message]
1998-10-07 0:00 ` Ian St. John
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
1998-10-02 0:00 ` Geoff Bull
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
1998-10-02 0:00 ` Fortran or Ada or gobbledygook? Wes Groleau
1998-10-05 0:00 ` Fortran or Ada? Terry Devine
1998-09-25 0:00 ` dewarr
[not found] ` <6udre0$ha1$1@nnrp1.dejane <6utg60$h6l$1@nnrp1.dejanews.com>
1998-10-01 0:00 ` robin_v
1998-09-22 0:00 ` Rakesh Malhotra
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
1998-09-23 0:00 Marin David Condic, 561.796.8997, M/S 731-96
-- strict thread matches above, loose matches on Subject: below --
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
1998-09-24 0:00 Walt Brainerd
1998-09-25 0:00 ` dewarr
1998-09-25 0:00 ` Robert I. Eachus
1998-10-05 0:00 Robert I. Eachus
1998-10-05 0:00 Condic, Marin D.
1998-10-05 0:00 robin
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