On Sep 29, 2008, at 10:51 AM, David Møller Hansen wrote:
> > Thank you for you answer Justin and I should also apologize for my > badly formulated question but you understood it correctly. > > I just can't get SAGE to eat the line you write f=x^2+x+F1(1), it > complains with: TypeError: unsupported operand parent(s) for '+': > 'Symbolic Ring' and 'Finite Field in a of size 2^7' Any time you see 'Symbolic Ring', or something similar, in an error message, you have run afoul of some short-cuts built into sage to make things simple for those who are "new" to sage, or are just using it as a quick and dirty calculator. The issue is that 'x' is predeclared as a symbolic calculus variable, and you want it to be an indeterminate for use in a polynomial ring. My reply earlier finessed the problem by not mentioning that I actually had this between defining F1 and defining f: sage: P1.<x>=PolynomialRing(F1) When you do this, your polynomial will actually be an element in F1 [x], and not some strange symbolic thing that doesn't play well with others :-} In short, the correct way to do what I showed earlier is sage: F1.<a> = GF(2^7) sage: P1.<x>=PolynomialRing(F1) sage: f=x^2+x+F1(1) sage: F2=F1.extension(f,'u') sage: F2 Univariate Quotient Polynomial Ring in u over Finite Field in a of size 2^7 with modulus u^2 + u + 1 sage: a in F2 True (which I just verified in a fresh run of sage 3.1.1). Sorry for the confusion. Justin -- Justin C. Walker, Curmudgeon-At-Large Director Institute for the Enhancement of the Director's Income -------- Here lies Lester Moore Two bullets from a .44 No less, no more -------- --~--~---------~--~----~------------~-------~--~----~ 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://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
