Hi,

Thanks for the patch, I'll have a look at the comparison functions
when I have some time, surely next week.
Where can I find the one defined by Sage ?

I have another question: are the source codes of GiNaC and pynac still
"synchronized" in some way ?
I saw that some recent changes are similar in both git repositories,
but as I was going through the source code, I saw that
numeric::do_print_csrc is defined in GiNaC but not in pynac.

Regards,

On 12 sep, 15:40, Burcin Erocal <bur...@erocal.org> wrote:
> Hi Jean-Pierre,
>
> On Thu, 9 Sep 2010 02:13:27 -0700 (PDT)
>
> Jean-Pierre Flori <jpfl...@gmail.com> wrote:
> > I created a Ticket on Sage's Trac:
> >http://trac.sagemath.org/sage_trac/ticket/9880
>
> > It could be a problem with the comparison function
> > "expair_rest_is_less" used by "std::sort" function like in the
> > following link:
> >http://gcc.gnu.org/ml/gcc-bugs/2010-08/msg01163.html
>
> This is indeed the problem. Thanks for tracking it down.
>
> In the process of adapting GiNaC for use in Sage, I changed the
> comparison functions to give a consistent order between different runs.
> Apparently, the new comparison functions I wrote are not consistent.
>
> For a long time, I wanted to rip out these new functions, and use them
> only for printing. The following patch is a first step towards this:
>
> http://sage.math.washington.edu/home/burcin/pynac/pynac_order.patch
>
> After applying this patch to pynac (see here [1] for instructions on
> how to set up a pynac development environment), the segfault you
> reported, and the bug at #9046 goes away.
>
> Note that this is very much a work in progress. I didn't take care to
> make sure these comparison functions are consistent either. In the
> process of copying things over, I even flipped a few signs in the
> results.
>
> This needs much work to be finished, we need to make sure the order
> is consistent and correct, and it matches the one currently used by
> Sage. The issue of accessing the operands of a symbolic expression also
> needs to be sorted out, but that's merely a user interface issue.
>
> I'd appreciate help with any of this, since I don't have much time to
> spend on Sage/pynac these days. I'd be glad to answer any questions
> though.
>
> Cheers,
> Burcin

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