On Tue, Sep 27, 2016 at 4:18 AM, William Stein <wst...@gmail.com> wrote:
> On Mon, Sep 26, 2016 at 6:55 PM, Jonathan Bober <jwbo...@gmail.com> wrote: > > On Mon, Sep 26, 2016 at 11:52 PM, William Stein <wst...@gmail.com> > wrote: > >> > >> On Mon, Sep 26, 2016 at 3:27 PM, Jonathan Bober <jwbo...@gmail.com> > wrote: > >> > In the matrix_integer_dense charpoly() function, there is a note in > the > >> > docstring which says "Linbox charpoly disabled on 64-bit machines, > since > >> > it > >> > hangs in many cases." > >> > > >> > As far as I can tell, that is not true, in the sense that (1) I have > >> > 64-bit > >> > machines, and Linbox charpoly is not disabled, (2) > >> > charpoly(algorithm='flint') is so horribly broken that if it were ever > >> > used > >> > it should be quickly noticed that it is broken, and (3) I can't see > >> > anywhere > >> > where it is actually disabled. > >> > > >> > So I actually just submitted a patch which removes this note while > >> > fixing > >> > point (2). (Trac #21596). > >> > > >> > However... > >> > > >> > In some testing I'm noticing problems with charpoly(), so I'm > wondering > >> > where that message came from, and who knows something about it. > >> > >> Do you know about "git blame", or the "blame" button when viewing any > >> file here: https://github.com/sagemath/sage/tree/master/src > > > > > > Ah, yes. Of course I know about that. And it was you! > > > > You added that message here: > > Dang... I had a bad feeling that would be the conclusion :-) Well, I'm sure you've done one or two things in the meantime that will allow me to forgive this one oversight. > In my defense, Linbox/FLINT have themselves changed a lot over the > years... We added Linbox in 2007, I think. > > Yes. As I said, this comment, and the design change, is ancient. In some limiting testing, linbox tends to be faster than flint, but has very high variance in the timings. (I haven't actually checked flint much.) Right now I'm running the following code on 64 cores, which should test linbox: import time @parallel def test(n): start = time.clock() f = B.charpoly() end = time.clock() runtime = end - start if f != g: print n, 'ohno' return runtime, 'ohno' else: return runtime, 'ok' A = load('hecke_matrix') A._clear_cache() B, denom = A._clear_denom() g = B.charpoly() B._clear_cache() import sys for result in test(range(100000)): print result[0][0][0], ' '.join([str(x) for x in result[1]]) sys.stdout.flush() where the file hecke_matrix was produced by sage: M = ModularSymbols(3633, 2, -1) sage: S = M.cuspidal_subspace().new_subspace() sage: H = S.hecke_matrix(2) sage: H.save('hecke_matrix') and the results are interesting: jb12407@lmfdb5:~/sage-bug$ sort -n -k 2 test_output3 | head 30 27.98 ok 64 28.0 ok 2762 28.02 ok 2790 28.02 ok 3066 28.02 ok 3495 28.03 ok 3540 28.03 ok 292 28.04 ok 437 28.04 ok 941 28.04 ok jb12407@lmfdb5:~/sage-bug$ sort -n -k 2 test_output3 | tail 817 2426.04 ok 1487 2466.3 ok 1440 2686.43 ok 459 2745.74 ok 776 2994.01 ok 912 3166.9 ok 56 3189.98 ok 546 3278.22 ok 1008 3322.74 ok 881 3392.73 ok jb12407@lmfdb5:~/sage-bug$ python analyze_output.py test_output3 average time: 53.9404572616 unfinished: [490, 523, 1009, 1132, 1274, 1319, 1589, 1726, 1955, 2019, 2283, 2418, 2500, 2598, 2826, 2979, 2982, 3030, 3057, 3112, 3166, 3190, 3199, 3210, 3273, 3310, 3358, 3401, 3407, 3434, 3481, 3487, 3534, 3546, 3593, 3594, 3681, 3685, 3695, 3748, 3782, 3812, 3858, 3864, 3887] There hasn't yet been an ohno, but on a similar run of 5000 tests computing A.charpoly() instead of B I have 1 ohno and 4 still running after 5 hours. (So I'm expecting an error in the morning...) I think that maybe I was getting a higher error rate in Sage 7.3. The current beta is using a newer linbox, so maybe it fixed something, but maybe it isn't quite fixed. Maybe I should use a small matrix to run more tests more quickly, but this came from a "real world" example. > -- > William (http://wstein.org) > > -- > You received this message because you are subscribed to the Google Groups > "sage-devel" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to sage-devel+unsubscr...@googlegroups.com. > To post to this group, send email to sage-devel@googlegroups.com. > Visit this group at https://groups.google.com/group/sage-devel. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
