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/CAAWYfq3sD5Sf3i%3DxV3fs29os7_4CC-28iGZPH9RJVDj_8npgzA%40mail.gmail.com.
