Hi Chris, On Thu, Mar 19, 2009 at 8:17 AM, Chris Godsil <cgod...@uwaterloo.ca> wrote: > > I want to compute determinants of matrix polynomials, for matrices up > to 20 x 20, say. > The attached transcript seems to indicate 9 or 10 might be my limit. > (Or it's late > and I am being stupd?) > > ---------------------------------------------------------------------- > | Sage Version 3.4, Release Date: > 2009-03-11 | > | Type notebook() for the GUI, and license() for information. | > ---------------------------------------------------------------------- > # intel mac pro, binary distribution > > sage: P = graphs.PetersenGraph() > sage: P.delete_edge([0,1]) > sage: P.degree() > [2, 2, 3, 3, 3, 3, 3, 3, 3, 3] > sage: P > Petersen graph: Graph on 10 vertices ## but P is not the Petersen > graph now > sage: A = P.am() > sage: Id = identity_matrix(10) > sage: R.<t> = QQ[] > sage: (t+1)^5 > t^5 + 5*t^4 + 10*t^3 + 10*t^2 + 5*t + 1 > sage: M = t*Id - A; M > > [ t 0 0 0 -1 -1 0 0 0 0] > [ 0 t -1 0 0 0 -1 0 0 0] > [ 0 -1 t -1 0 0 0 -1 0 0] > [ 0 0 -1 t -1 0 0 0 -1 0] > [-1 0 0 -1 t 0 0 0 0 -1] > [-1 0 0 0 0 t 0 -1 -1 0] > [ 0 -1 0 0 0 0 t 0 -1 -1] > [ 0 0 -1 0 0 -1 0 t 0 -1] > [ 0 0 0 -1 0 -1 -1 0 t 0] > [ 0 0 0 0 -1 0 -1 -1 0 t] > sage: M.det() ## and sage hangs
Well, it hangs for a while and then gives me this: sage: M.det() t^10 - 14*t^8 + 65*t^6 - 16*t^5 - 128*t^4 + 72*t^3 + 84*t^2 - 80*t + 16 -- Regards Minh Van Nguyen --~--~---------~--~----~------------~-------~--~----~ 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 URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
