Last year after less than two days I could finish a calculation and write to William:
> -------- Original Message -------- > Subject: dance(10) > Date: Thu, 09 Mar 2006 00:10:19 +0100 > From: Jaap Spies <[EMAIL PROTECTED]> > To: William Stein <[EMAIL PROTECTED]> > > William, > > Some time ago, dance(10) finished: > > sage: time dance(10) > [1, 90, 3405, 71040, 901152, 7225344, 36862960, 117340800, 221170456, > 220658800, 87396728] > h^10 - 35*h^9 + 675*h^8 - 8610*h^7 + 78435*h^6 - 523467*h^5 + > 2562525*h^4 - 9008160*h^3 + 21623220*h^2 - 31840760*h + 21750840 > CPU times: user 141822.70 s, sys: 18387.03 s, total: 160209.74 s > Wall time: 165997.13 > > > Jaap To day I got with sage-2.8.8.1: > sage: time dance(10) > > > ------------------------------------------------------------ > Unhandled SIGSEGV: A segmentation fault occured in SAGE. > This probably occured because a *compiled* component > of SAGE has a bug in it (typically accessing invalid memory) > or is not properly wrapped with _sig_on, _sig_off. > You might want to run SAGE under gdb with 'sage -gdb' to debug this. > SAGE will now terminate (sorry). > ------------------------------------------------------------ With sage -gdb: > sage: time dance(9) > h^9 - 27*h^8 + 414*h^7 - 4158*h^6 + 29421*h^5 - 148743*h^4 + 530796*h^3 - > 1276992*h^2 + 1866384*h - 1255608 > CPU times: user 1786.82 s, sys: 23.05 s, total: 1809.87 s > Wall time: 1831.52 > > sage: time dance(10) > > Program received signal SIGSEGV, Segmentation fault. > [Switching to Thread -1208523072 (LWP 30162)] > 0x0064d473 in strlen () from /lib/libc.so.6 > (gdb) The program (see below) uses methods from sage.matrix.matrix2.pyx Jaap ########################################################################## # Copyright (C) 2006 Jaap Spies, [EMAIL PROTECTED] # # Distributed under the terms of the GNU General Public License (GPL): # # http://www.gnu.org/licenses/ ########################################################################## """ Usage from sage sage: attach 'dancing.sage' sage: dance(4) h^4 - 2*h^3 + 9*h^2 - 8*h + 6 """ # use variable 'h' in the polynomial ring over the rationals h = QQ['h'].gen() def dance(m): """ Generates the polynomial solutions of the Dancing School Problem Based on a modification of theorem 7.2.1 from Brualdi and Ryser, Combinatorial Matrix Theory. See NAW 5/7 nr. 4 december 2006 p. 285 INPUT: integer m OUTPUT: polynomial in 'h' EXAMPLE: sage: dance(4) h^4 - 2*h^3 + 9*h^2 - 8*h + 6 AUTHOR: Jaap Spies (2006) """ n = 2*m-2 M = MatrixSpace(ZZ, m, n) A = M([0 for i in range(m*n)]) for i in range(m): for j in range(n): if i > j or j > i + n - m: A[i,j] = 1 rv = A.rook_vector() # print rv s = sum([(-1)^k*rv[k]*falling_factorial(m+h-k, m-k) for k in range(m+1)]) print s --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@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-devel URLs: http://sage.scipy.org/sage/ and http://modular.math.washington.edu/sage/ -~----------~----~----~----~------~----~------~--~---
