On Nov 5, 11:27 pm, Martin Albrecht <[EMAIL PROTECTED]>
wrote:
Hello,
> > Let G be some Gröbner basis, obtained with Singular (via the
> > interface). I'd like to have a list comprising the exponent vector (as
> > a python list/tuple of integers) of each standard monomial for G, in a
> > fixed weighted degree d.
>
> > So, i could use weightKB(G, d, <intvec of degree weights>) via the
> > interface and get the exponent vectors from there. But this involves a
> > lot of communication between Sage and Singular and therefore is slow.
>
> But this one returns all the information you need at once, doesn't it? If so,
> I'd call it, then get the result as a string and perform string parsing on
> the result. Sometimes it also makes sense to have Singular pre-process the
> data for you such that it is easier to parse.
>
> > Do you have hints how to get the data in the quickest way? E.g.,
> > Michael wrote something about the interface behaving quadratic.
>
> I would also be interested in this.
For details see http://trac.sagemath.org/sage_trac/ticket/502
>
> > Does that mean it is better to send many small and simply structured data
> > packages through the interface, rather than sending few huge and
> > complicated data packages?
>
> Definitely not! Each send/receive is an interprocess communication via the
> operation system which is quite expensive given small sets of data. You
> certainly want to limit the number of communication acts.
>
> > weightKB is in Singular's standard.lib, hence, is interpreted code. I
> > thought it might be worth-while to implement the same thing in cython
> > (hence, compiled), but on the other hand, in order to do so one would
> > need to send information on the leading monomials of G from Singular
> > to Sage, which, again, is slow.
>
> This depends on the GB you have. If you just need it in a commutative
> polynomial ring you can call Ideal.groebner_basis('libsingular:std') or
> Ideal.groebner_basis('libsingular:slimgb') on your ideal. If your idea has to
> be a singular object (because it is e.g. in a non-commutative ring) it is
> probably better to stick to Singular for this task as the communication
> overhead would probably kill all your Cython speedups.
>
> Martin
>
Cheers,
Michael
> --
> name: Martin Albrecht
> _pgp:http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x8EF0DC99
> _www:http://www.informatik.uni-bremen.de/~malb
> _jab: [EMAIL PROTECTED]
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