[Python-Dev] Re: the "3*x works w/o __rmul__" bug

[Alex Martelli]

On Tuesday 28 October 2003 08:24 pm, Fernando Perez wrote:
> Hi all,
>
> I just wanted to add a small comment on this discussion, which I'd been
> following via the newsgroup mirror.

Thanks for your comments!  I didn't even know we HAD an ng mirror...


> Python is picking up a lot of steam in the scientific computing community,
> and in science it is quite common to encounter non-commutative
> multiplication. Just to remind Guido from his old math days :), even for
> square matrices, AB!=BA in most cases.  The Matrix class supplied with

Yes, of course, you're right.  However, the most specific problem is: do
you know of ANY use cases where
   A*x
and
   x*A
should give different results, or the former should succeed and the latter
should fail, *when x is an integer*?

If you can find any use case for that, even in an obscure branch of
maths, then clearly the urgency of fixing this bug goes WAY up.

Otherwise -- if having the problem specifically for an integer x ONLY
should not affect anything -- the bug is basically only going to show
up in software that's under development and not yet completed, or
else not fully correct.  I _still_ want to fix it, but... the urgency of doing
so is going to be different, as I'm sure you'll understand!


Thanks again for your help -- we DO need to hear from users!!!

Alex