Thank you William. Unfortunately the coefficient command does not appear to allow me to determine what terms the coefficients are associated with. If I had the expression:
a*x^2+b*x*y +c*y^2 and the b term was zero the output would be [a,c] but I would not know if the zero element was a, b, or c. That's why I was trying to get coeff() to work because it allows me to check for each term individually. Is there a way to coerce the groebner_basis() output into the correct form to allow coeff() to work? David On Sep 14, 1:48 pm, "William Stein" <[EMAIL PROTECTED]> wrote: > On 9/14/07, David Stahl <[EMAIL PROTECTED]> wrote: > > > > > I am using the sage command groebner_basis(). > > > David > > OK, this just seems like a case of showing you an example will > answer the question. Let me know if it doesn't: > > sage: P.<a,b,c> = PolynomialRing(QQ,3, order='lex') > sage: I = sage.rings.ideal.Katsura(P,3) # regenerate to prevent caching > sage: g = I.groebner_basis() > sage: g[0].coefficients() > [84, -40, 1, 1] > sage: g[1].coefficients() > [7, 210, -79, 3] > sage: g[2].coefficients() > [1, 2, 2, -1] > sage: g > [84*c^4 - 40*c^3 + c^2 + c, 7*b + 210*c^3 - 79*c^2 + 3*c, a + 2*b + 2*c - 1] > > > > > > > On Sep 14, 1:05 pm, Martin Albrecht <[EMAIL PROTECTED]> > > wrote: > > > On Friday 14 September 2007, David Stahl wrote: > > > > > Can anyone tell me how to extract the coefficients from the results of > > > > groebner()? > > > > Dou you mean Ideal.groebner_basis i.e. the SAGE method or > > > SingularElement.groebner i.e. the Singular command? As you try to call > > > coeff > > > you probably refer tot he Singular function. Singular doesn't have a > > > command > > > coeff but it has a command coef (notice the single 'f'), described here: > > > >http://www.singular.uni-kl.de/Manual/3-0-3/sing_175.htm#SEC215 > > > > Martin > > > > -- > > > 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] > > -- > William Stein > Associate Professor of Mathematics > University of Washingtonhttp://wstein.org --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://sage.math.washington.edu/sage/ and http://sage.scipy.org/sage/ -~----------~----~----~----~------~----~------~--~---
