From: "Gary L. Scott" <scottg@flash.net>
Subject: Re: Fortran or Ada?
Date: 1998/10/08
Date: 1998-10-08T00:00:00+00:00 [thread overview]
Message-ID: <361CA542.F48ECAEC@flash.net> (raw)
In-Reply-To: 361a94ca.0@news.passport.ca
Ian St. John wrote:
> dewarr@my-dejanews.com wrote in message
> <6vdfq4$p1$1@nnrp1.dejanews.com>...
> >In article <YGdS1.73461$hx3.8968466@HME2.newscontent-01.sprint.ca>,
> > "Ian St. John" <istjohn@sprint.ca> wrote:
> >>
> >> Testing by itself can never guarantee correct code. The testing is
> just
> to
> >> determine syntax errors, oversights, etc.
> >
> >That's a bit strong, there are definitely cases where testing can be
> >exhaustive, e.g. in checking out a sqrt routine for IEEE short form
> >arithmetic. Indeed it is almost practical to do exhaustive testing on
>
> >long format division (which would have saved Intel many millions of
> >dollars :-)
>
> Exhaustive testing would have taken way too long. And if you test
> exhaustively for real*4, does that mean that real*8 or real*10 values
> are
> correct? Much faster to verify the lookup table as having been copied
> over
> correctly. That had already been 'exhaustively tested'. Nobody looked.
> That
> is when problems creep in.
>
> Management oversights, decisions, and plain lack of common sense.
> 'Check
> that it's plugged in *first*'.
>
Wasn't that the Denver airport?
> Like the Dallas airport. A two hour session with LISP would have told
> them
> that the queuing for the luggage carts wouldn't work. ( Test reported
> in
> IEEE spectrum or computer mag analyzing failure ). The multi-million
> dollar
> fullblown simulator that was to verify the design of the program was
> still
> being 'debugged' long after the airport went into operation. It was
> scheduled to be finished a year after it became totally irrelevant.
>
> Can you tell me why they built a multi-million dollar simulator that
> wouldn't give them the answer in time to be of any use? Duuuuhhhhhh.
> Guess
> someone wanted a big budget project.
>
> Another example of why testing will never guarantee correct coding
> might be
> the Win95 midnight bug. It bumps the date by two days if you happen to
> shut
> down on a particular second before midnight. It took Microsoft days to
>
> confirm the bug, even having good evidence it was there, because it
> had to
> be one specific second, and that changed with the cpu speed, etc.
>
> Complicated systems just can't be 'exhaustively' tested. Each new
> subsystem
> in Win95, or Vxd, or DLL makes for that many more combinations of
> interactions. You get a "combinatorial explosion". Brute force doesn't
> work.
>
> It has to be a combination of design, mathematics, testing, and
> management.
> How does this module affect others? Will any new timing delays affect
> latency in this realtime module. Etc. And you may never get that 'last
> bug'.
>
> People coded it, and some programmers are better than others. So you
> design
> it with robust operation in mind. Then keep squashing them, as they
> come
> out, until you just can't find any more. You have Bill analyze Fred's
> code,
> Harry analyze Bill's code, and Fred analyze Harry's code. Change the
> assignments, etc. to keep everyone aware of the big picture, and how
> implementation details may affect the likelyhood of specific failures.
> Have
> group discussions, where details can be brought to light. Someone may
> have
> experience ( like LISP programming ) that can simplify the testing, or
> point
> to possible failure modes not currently in discussion.
>
> **** NOTE: These opinions are my own. I am old enough to make up my
> own
> mind, so there.. ****
--
Gary L. Scott
mailto:scottg@flash.net
mailto:webmaster@fortranlib.com
http://www.fortranlib.com
next prev parent reply other threads:[~1998-10-08 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 ` 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 ` Joel Seidman
1998-09-24 0:00 ` Marc A. Criley
1998-09-24 0:00 ` Jeff Templon
1998-09-25 0:00 ` dewarr
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
1998-09-24 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 ` Dean F. Sutherland
1998-09-29 0:00 ` Gautier.DeMontmollin
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 [this message]
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
1998-10-06 0:00 ` Fortran or Ada? Michel OLAGNON
1998-10-07 0:00 ` Ian St. John
1998-09-29 0:00 ` Dean F. Sutherland
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
[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
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
-- strict thread matches above, loose matches on Subject: below --
1998-09-23 0:00 Marin David Condic, 561.796.8997, M/S 731-96
1998-09-24 0:00 Walt Brainerd
1998-09-25 0:00 ` dewarr
1998-09-25 0:00 ` Robert I. Eachus
1998-10-05 0:00 robin
1998-10-05 0:00 Condic, Marin D.
1998-10-05 0:00 Robert I. Eachus
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