Hi, Dima; thanks for taking the time to help out a noob -- again. This is what I did:
sage: a,b,y,z=var('a,b,y,z') sage: p=z*x^2+x^2-(x^2+y^2)*(a*x-2*b*y)+z*y^2+y^2 sage: type(p) <type 'sage.symbolic.expression.Expression'> The book says that I should be able to do this: sage: p.collect(x).collect(y) And get this in return: sage: 2*b*y*x^2 + 2*b*y^3−(a*x−z−1)*x^2−(a*x−z−1)*y^2 But instead, I get: -a*x^3 + 2*b*x^2*y + 2*b*y^3 - (a*x - z - 1)*y^2 + x^2*z + x^2 ??? On Sun, Aug 19, 2018 at 10:46 AM, Dima Pasechnik <dimp...@gmail.com> wrote: > how is p created? what is the output of > > type(p) > > -- > You received this message because you are subscribed to the Google Groups > "sage-support" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to sage-support+unsubscr...@googlegroups.com. > To post to this group, send email to sage-support@googlegroups.com. > Visit this group at https://groups.google.com/group/sage-support. > For more options, visit https://groups.google.com/d/optout. > -- The Great Secret? "It is, and It isn't." -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To post to this group, send email to sage-support@googlegroups.com. Visit this group at https://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/d/optout.