From: "Ian St. John" <istjohn@high-sense.com>
Subject: Re: Fortran or Ada?
Date: 1998/10/06
Date: 1998-10-06T00:00:00+00:00 [thread overview]
Message-ID: <361a94ca.0@news.passport.ca> (raw)
In-Reply-To: 6vdfq4$p1$1@nnrp1.dejanews.com
dewarr@my-dejanews.com wrote in message <6vdfq4$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*'.
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.. ****
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 ` 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 ` 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
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 ` 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 ` dewarr
1998-10-05 0:00 ` Ian St. John
1998-10-06 0:00 ` dewarr
1998-10-06 0:00 ` Ian St. John [this message]
1998-10-08 0:00 ` Gary L. Scott
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? Toon Moene
1998-10-06 0:00 ` Jonathan Guthrie
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
1998-10-05 0:00 ` Richard D Riehle
1998-10-05 0:00 ` dewarr
1998-10-06 0:00 ` 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
-- 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 ` Dean F. Sutherland
1998-09-24 0:00 ` Gisle S{lensminde
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 robin
1998-10-05 0:00 Condic, Marin D.
1998-10-05 0:00 Robert I. Eachus
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