Hi Enrique, On 2015-02-19, Enrique Artal <[email protected]> wrote: > 1. For the first one, it was already reported, with an open ticket, but > I am worried about it since it produces wrong outputs.
If there is an open ticket for it, then there is no need to report it again. However, if it gives wrong results and is not fixed soon then I think there should be a different ticket adding a "stopgap" (that will print a warning to the user that the computation may have a wrong result. Has the stopgap ticket not been opened as well? > Maybe the point is that for Singular the actual ring defined as > R is not the polynomial ring but the localization by the order That's very likely the problem. And I think that the cleanest solution would be to take this into account by changing the string representation of a polynomial ring in local ordering: It should not be called "polynomial ring over ... with generators ..." but "localisation at ... of polynomial ring over ... with generators ...". > (i.e., we > can divide by any non-zero polynomial whose leading term is a constant); > in > fact, for algorithmic purposes one always works with polynomials (taking > out the possible denominators wisely), but the ring is not a polynomial. I > guess that a small change in the way of dividing polynomial would suffice. Very probably not. We would need to deviate from the polynomial backend (i.e., Singular) fairly much to implement this, which would be complicated and slow. > 2. When doing some test for the above problem I realize that > *R.<x>=PolynomialRing(QQ,order='neglex') > *does not take into account the order (the above *f* is not a unit). Yes, it is, since the ring is in fact localised. > This is not really an issue, the problem is the fact that the function > accept the entry *order* but it ignores it silently. Ahm, why do you think it is ignored? Best regards, Simon -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
