On Tue, Jul 7, 2009 at 7:53 AM, Bjarke Hammersholt Roune<bjarke.ro...@gmail.com> wrote: > >> I very strongly agree that such a limitation is a major problem. >> The only way I can think of to deal with it, is if any such exponent >> appears, we switch to the polydict (nonsingular) representation, and >> everything gets way slower, and Groebner basis computations switch to >> a toy implementation + warning (or just fail with an error >> immediately?). >> > I think dynamically switching representations when running into > limitations of one representation is a very good solution, though I > think it will be difficult (though not impossible) to make this work > in practice. E.g. if Singular overflows in the middle of a > computation, then Sage would need to discover this, recover the state > things had before the computation, change to the polydict ring, and > then restart the same computation - specifically Sage would need to > know how to do this for each computation. This also presupposes that > overflow errors are always reported by Singular (and other software > with similar limitations), which seems not to be the case.
I think this is definitely possible. We add some extra code to __mul__ and a few other commands. > I'm going to check that the issues in the trac tickets above are > indeed due to Singular, then report them to the Singular team and ask > them whether it is a policy for Singular to always report overflow. If > the Singular team view silent overflow to be an important bug needing > fixing, then I don't think it's as much of a problem as I otherwise > would. I strongly suspect they *will* care and view this as important. You might mention that at least I do. >> However, much to my surprise the Sage-native polydict implementation >> is in fact broken even worse!!!! (please report this to trac). >> > As a friendly comment I experience this to be bossy. Oops, sorry. I should have written "please report this to trac, if you have the time and it isn't already there." I hope I haven't offended you, since that's not at all my intention. And I'm mostly certainly not the boss of you. > In any case, it's > been in trac since Sage Days 16, where you may have noticed that I > used polynomials for the small examples in my presentation of Frobby, > and then switched to a list-of-exponents representation for the > examples with large exponents - because it wouldn't work any other way > I could find after asking around. Yep, I remember that. > > http://trac.sagemath.org/sage_trac/ticket/6428 > Thanks. william --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to sage-devel-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
