Wolfgang Jenkner <wjenkner@inode.at> wrote:
>Bill Dubuque <wgd@zurich.csail.mit.edu> writes:
>>
>> Yes, I fixed all the "quotient is not exact" bugs
>> a long time ago in the commercial version.
>
> At the time of
>
> http://www.math.utexas.edu/pipermail/maxima/2002/002378.html
>
> I received a private email message which stated
>
> Oddly enough, the same bug occurs in the commercial macsyma.
>
> The bug in question is that in Maxima
>
> (C1) gcd:subres;
> (D1) SUBRES
> (C2) integrate(sin(3/2)/(1-cos(3/2)^2*sin(t)^2),t,0,2*%pi);
>
> gives the "quotient is not exact" error.
>
> So the last version of commercial macsyma doesn't have this bug?
The commercial version uses SPMOD as the default GCD algorithm,
which avoids this and many other related bugs.
Macsyma, like most other general purpose computer algebra systems,
was not designed correctly to handle computations in algebraic
number rings and fields. Indeed, many (but not all) of the original
designers of these systems lacked the mathematical background to
properly appreciate these issues. The end result is that these
systems have algorithms being incorrectly invoked in contexts
where they make no sense.
I've long desired to correct these problems in Macsyma but,
unfortunately, there was little demand for such by the powers
that be after its unfortunate commercialization (as a consultant
I was responsible for most of the hardcore math work in the
commercial Macsyma). If we could find someone to fund further work
I'd be delighted to continue work but, alas, I can't afford to do
much volunteer work in my present situation (the local high-tech
economy in (Mass) USA is by far the worst in my lifetime -
many are now struggling to survive since there has been very
little hiring after the big dot-com crash of 2000).
If anyone can revive Macsyma in any context (academic,
commercial) I'd be very interested in being involved.
I've invested far too many years (25) of my life to
stand by and let it all go to waste. Unfortunately, given
the present state of affairs, I don't know any way to make
a living on Macsyma. Perhaps someone in academia (Fateman,
Wang?) can manage to get funding to continue research.
-Bill Dubuque