On Wed, Apr 21, 2010 at 8:06 PM, Elizabeth <papag...@earthlink.net> wrote: > I'd like to know if there is a way to define a variable in Sage as non- > commuting. > I am trying to multiply a few matrices together and take the trace, > *but* the matrix entries are non-commuting elements. So, I need Sage > to leave a term like a*x*a as-is and not change it to x*a^2.
You could work over the FreeAlgebra: sage: R.<a,b> = FreeAlgebra(QQ, 2) sage: a*b + b*a a*b + b*a sage: s = matrix(R) sage: s = matrix(R, [[a,b],[b,a]]); s [a b] [b a] sage: s*s [a^2 + b^2 a*b + b*a] [a*b + b*a a^2 + b^2] sage: b*s*s [ b*a^2 + b^3 b*a*b + b^2*a] [b*a*b + b^2*a b*a^2 + b^3] --Mike -- 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
