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+unsubscr...@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/CAAWYfq0m0FyTqHnvgys40dj69kO4_DdyMWhG72B%2Bybvc63v8tg%40mail.gmail.com.
