swap_row does not work on modular matrices

[sagetrac-janwil123]

For some reason, swap_row does not work if the elements of the matrix are treated as integers modulo something. The code to reproduce the bug is the following:

A = matrix(ZZ, 2,[1,2,3,4])
B = copy(A)
B.swap_rows(0,1)
print B,'\n'
B.swap_columns(0,1) # So far so good
print B,'\n'
C = A.apply_map(lambda x:mod(x,8))
C.swap_rows(0,1) # This line does not work
print C,'\n'
C.swap_columns(0,1) # But this one does
print C

The bug reproduces every time on Mac OSX 10.6, SAGE version 4.3.1.

Component: linear algebra

Author: Mike Hansen

Reviewer: Nicolas Borie

Merged: sage-4.3.4.alpha1

Issue created by migration from https://trac.sagemath.org/ticket/8264

[mwhansen]

comment:1

Attachment: trac_8264.patch.gz

[mwhansen]

Author: Mike Hansen

[sagetrac-nborie]

comment:2

The patch fix the ticket and add the good test.

Positive review from me.

[sagetrac-nborie]

Reviewer: Nicolas Borie

[mwhansen]

Merged: sage-4.3.4.alpha1