Re: Ariane5 FAQ

[snarflemike@yahoo.com (Mike Silva)]

Hyman Rosen <hyrosen@mail.com> wrote in message news:<1058969472.350716@master.nyc.kbcfp.com>...
> 
> I'm not saying that the Ariane 4 people did anything unsuitable for
> the Ariane 4. But doing it this way made the code brittle.
> The investigation board said
>     "No reference to justification of this decision was found
>      directly in the source code. Given the large amount of
>      documentation associated with any industrial application,
>      the assumption, although agreed, was essentially obscured,
>      though not deliberately, from any external review."
> 
> This is exactly the kind of coding practice that leads to problems
> like integer overflow, buffer overflow, and Y2K issues. Shortcuts
> are taken in order to optimize a program for local conditions, but
> the dependencies are not communicated properly to people who then
> go on to use the code in situations where the local conditions no
> longer apply.

So you are arguing that, lacking written documentation to the
contrary, any piece of code should be assumed capable of handling all
possible input values in a way that is appropriate to all possible
systems in which the code is employed.  Tell me, honestly, would you
fly in a rocket designed under such assumptions?

No matter how many times you argue your case (and you do get points
for tenaciousness!) the fact is that the code did the right thing for
the Ariane-4 system, and the Ariane-5 people had no legitimate reason
to assume that what the code did would also be right in the Ariane-5
system.  As has been pointed out, there were other portions of the
(correct) Ariane-4 software which were also used without legitimate
justification in the -5, and would probably also, in their turn, have
destroyed the -5.