I opened a ticket on trac regarding this problem: http://trac.sagemath.org/sage_trac/ticket/11652
* rafaeldleon <[email protected]> [2011-07-28 18:00:25 -0700]: > Dear Julian, > > Thank you very much for your help. It seems like an error to me too. > I am using your solution in my code and is working nicely. > > Should we report this error in any other place? > > Thank you again, > > Rafael > > On Jul 25, 4:42 pm, Julian Rüth <[email protected]> wrote: > > Apparently, this is caused by a problem in degree() which is used in > > polynomial(). In your example: > > > > sage: pol2.degree(q) > > 0 > > sage: pol2.degree(p) > > 3 > > > > You get the expected behavior if you bring q into pol2.parent() > > explicitly: > > > > sage: q=pol2.parent()(q) > > sage: pol2.degree(q),pol2.polynomial(q) > > (3, 4*q^3 + 3*q + 2) > > > > So, this seems like an error to me. In the implementation of degree() > > the line reading > > > > return singular_polynomial_deg(p, (<MPolynomial_libsingular>x)._poly, r) > > > > should probably be changed (x is the generator passed to the method). > > But maybe somebody who knows more about the singular/sage connection can > > say more about this. > > > > cheers, > > julian > > > > * rafaeldleon <[email protected]> [2011-07-25 12:31:29 -0700]: > > > > > > > > > > > > > > > > > Hello all, > > > > > I don t know if the following is an error in the implementation of the > > > method polynomial > > > or if I am using it in a way that is not intended, but it seems that > > > the use of the method > > > polynomial changes when I am in a polynomial ring with 2 or with 3 > > > variables. > > > > > pol and pol2 are the "same" polynomial in rings with 3 or 2 variables > > > resp. and > > > the method pol.polynomial(q) and pol2.polynomial(q) return different > > > answers. > > > > > sage: R.<p,q,t>=ZZ[] > > > sage: pol=2+3*q+4*q^3;pol > > > 4*q^3 + 3*q + 2 > > > sage: parent(pol) > > > Multivariate Polynomial Ring in p, q, t over Integer Ring > > > sage: pol2=pol.polynomial(t).coefficients()[0];pol2 > > > 4*q^3 + 3*q + 2 > > > sage: parent(pol2) > > > Multivariate Polynomial Ring in p, q over Integer Ring > > > sage: pol2.polynomial(q) > > > 2 > > > sage: pol.polynomial(q) > > > 4*q^3 + 3*q + 2 > > > > > Can anyone give me some insight about why I am getting these > > > different answers? > > > > > Thanks! > > > > > Rafael > > > > > -- > > > To post to this group, send email to [email protected] > > > To unsubscribe from this group, send email to > > > [email protected] > > > For more options, visit this group > > > athttp://groups.google.com/group/sage-support > > > URL:http://www.sagemath.org > > -- > To post to this group, send email to [email protected] > To unsubscribe from this group, send email to > [email protected] > For more options, visit this group at > http://groups.google.com/group/sage-support > URL: http://www.sagemath.org -- To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
