Not so many candidates. I guess this is one of the following
Trac #26546: matrix_gfpn_dense: refactor field_to_int()
Trac #23214: enhance sparse integer matrix with linbox (+ cleaning)
Le 09/10/2019 à 18:31, Dima Pasechnik a écrit :
This is now https://trac.sagemath.org/ticket/28586
It would be great not to have to do git bisect on this, anyone can point
out to a suspect ticket?
Thanks!
On Thu, Oct 10, 2019 at 12:06 AM Robert Samal <robert.sa...@gmail.com>
wrote:
Indeed it works in Sage 8.4.
Thanks!
On Wednesday, October 9, 2019 at 8:34:41 AM UTC-7, Dima Pasechnik wrote:
This got broken in Sage 8.5.
(still works in 8.4)
On Wed, Oct 9, 2019 at 6:09 AM David Joyner <wdjo...@gmail.com> wrote:
On Wed, Oct 9, 2019 at 1:33 AM Robert Samal <rober...@gmail.com> wrote:
Sorry, F=GF(3), I made my original example shorter and didn't read it
properly.
So the full problematic code is
B=matrix(GF(3), 2,2,[1,0,1,0], sparse=True)
v=vector(GF(3), [1,1])
B.solve_right(v)
Yes. I can confirm it works with "sparse=True" removed *or* if GF(3) is
replaced by ZZ.
So there's an easy workaround but maybe the docs or the code has a bug?
Thanks for reporting.
Thanks,
Robert
On Tuesday, October 8, 2019 at 5:17:59 PM UTC-7, Robert Samal wrote:
I am trying to solve a rather large linear systems of equations of
GF(3). As the matrices are sparse, I thought that adding "sparse=True" to
the constructor of the matrix could be of help. However, I ran to a strange
error message.
B=matrix(GF(3), 2,2,[1,0,1,0], sparse=True)
v=vector(F, [1,1])
B.solve_right(v)
The above code yields the following
TypeError: Cannot convert sage.matrix.matrix_modn_sparse.Matrix_modn_sparse to
sage.matrix.matrix_integer_sparse.Matrix_integer_sparse
I am hesitant to paste the whole error message here, but it ends with reference
to file
SageMath/local/lib/python2.7/site-packages/sage/matrix/matrix_modn_sparse.pyx in
sage.matrix.matrix_modn_sparse.Matrix_modn_sparse._solve_matrix_linbox
(build/cythonized/sage/matrix/matrix_modn_sparse.cpp:11633).
I am using Sage 8.9, but the same issue was on 8.7 as well.
Few other observations:
-- works as expected for dense matrices -- or for sparse ones over integers
-- the same issue occurs whether y is a vector or a matrix
-- It behaves the same for systems with no solution.
Is there some hidden limitation of sparse matrices over finite fields?
I.e., is it a bug or feature? :-)
I tried to RTFM, but couldn't find this discussed. The page for sparse matrices
over
finite fields does not exactly promise the solve method, but it does not
mention it
would not work either. Is it possible to achieve what I want by other means (in
Sage).
Thanks.
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