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 ## but the following worked sage: K =graphs.CompleteGraph(3) sage: B =K.am() sage: Id = identity_matrix(3) sage: (t*Id-B).det() t^3 - 3*t - 2 sage: C = graphs.CubeGraph(3) sage: C 3-Cube: Graph on 8 vertices sage: Id = identity_matrix(8) sage: (t*Id-C.am()).det() t^8 - 12*t^6 + 30*t^4 - 28*t^2 + 9 # and the cycle on 9 vertices hangs --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
