On Feb 19, 6:38 am, ObsessiveMathsFreak <obsessivemathsfr...@gmail.com> wrote: > Basically, I want to restrict the variables of a multivariate > polynomial to a certain set of symbols. > > B.variables() should return > [x,y] > instead of > [a,x,y] > > How can this be done.
Maybe I misunderstand you, but this approach works fine in sage 4.8, and probably earlier: sage: R.<a> = QQ[] sage: P.<x,y> = R[] sage: f = a*x^2 - 2*y sage: f.variables() (x, y) That said, I can't factor a^2*x^2-y^2 going this route, because this type of polynomial tries to interact with a specific (different) backend. > (Incidentally, the Sage polynomial/ring documentation is absolute and > utter bedlam. Is it not possible for ordinary mortals to work with > polynomials without having to declare polynomials rings over > integers. ) Again, maybe I misunderstand you, but the polynomial rings given above are not over the integers, and there are examples of this in the documentation: http://www.sagemath.org/doc/constructions/rings.html#polynomial-rings Which I accessed via clicking on "Help/Documentation" from the home page, then on "View the online documentation", then on "Constructions", then on "Polynomial Rings". Could you be more specific as to where the bedlam lies? There's a doc days coming up, and I'm sure people working on documentation could use advice. regards john perry -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org