I've opened https://trac.sagemath.org/ticket/32961 to deal with this. At least we should check that the number of entries can be handled by the current implementation.
On Thu, Dec 2, 2021 at 11:31 AM Dima Pasechnik <dimp...@gmail.com> wrote: > > On Thu, Dec 2, 2021 at 11:17 AM 'jonatha...@googlemail.com' via > sage-devel <sage-devel@googlegroups.com> wrote: > > > > FF = GF(next_prime(1000000)) > > M = Matrix(FF, [[1, 2], [3, 4]]) > > M.__init__?? > > > > reveals that the indices are casted into a long. This might be the problem. > > right, seems to be the right place > > sage: M*N > 5600000000 > sage: 2^32 # long is 4 bytes, i.e. maximal value it holds is 2^32-1 > 4294967296 > > It's probably not the only place where <long> is used for indexing of > matrices (which are stuffed into 1-dim. arrays) > > Dima > > > > > Using Py_ssize_t or size_t might have been a better choice. > > > > Jonathan > > dim...@gmail.com schrieb am Mittwoch, 1. Dezember 2021 um 20:56:16 UTC+1: > >> > >> > >> > >> On Wed, Dec 1, 2021 at 4:39 PM Anton Mellit <mel...@gmail.com> wrote: > >> > > >> > When I create a very large matrix (the threshold may be 2^32 entries) > >> > from a list of vectors, the elements are not copied over correctly. > >> > Here is a "small" example: > >> > > >> > FF = GF(next_prime(1000000)) > >> > M = 70000 > >> > N = 80000 > >> > v1 = vector(FF, [FF(k) for k in range(N)]) > >> > v2 = vector(FF, [N] * N) > >> > vecs = [v1 + v2*FF(i) for i in range(M)] > >> > mat = matrix(FF, M, N, vecs) > >> > mat[0] == vecs[0] > >> > > >> > the last line returns "false". > >> > I understand the bug is not so easy to reproduce: the code above runs > >> > for about 40 minutes and needs about 50G of RAM. In fact, it is also > >> > strange that it takes so long: all the lines until "mat = matrix(FF, M, > >> > N, vecs)" take only about a minute. It shouldn't take so much more time > >> > to simply copy a bunch of vectors than it took to compute them. > >> > > >> Matrices in Sage are not just array, they come with parents - vector > >> spaces of matrices of this size. > >> Perhaps it's where the time bottleneck is - in creating the parent, that > >> code wasn't obviously optimised for these kinds of dimensions. > >> > >> As to the error... Hard to say, one needs to look at the code (and find a > >> machine to reproduce the example). > >> > >> Dima > >> > >> > >> > Sage version: 9.3 running on a 64 bit linux system > >> > > >> > > >> > -- > >> > 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+...@googlegroups.com. > >> > To view this discussion on the web visit > >> > https://groups.google.com/d/msgid/sage-devel/d06f39c6-f066-4e83-a2c1-2bbcba345f36n%40googlegroups.com. > > > > -- > > 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 view this discussion on the web visit > > https://groups.google.com/d/msgid/sage-devel/9c38f81a-f471-41e1-a36f-07b618232f47n%40googlegroups.com. -- 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 view this discussion on the web visit https://groups.google.com/d/msgid/sage-devel/CAAWYfq1SP17NR%3DnKjoRSspYhUfJ5wUtTKk4iFgCCEtZ5r_Ts0Q%40mail.gmail.com.
