#11358: matrix multiplication over ZZ sometimes gives incorrect results
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Reporter: tomc |
Owner:
Type: defect |
Status: needs_work
Priority: critical |
Milestone: sage-5.0
Component: linear algebra |
Resolution:
Keywords: matrix multiplication, multi-modular, integers, ZZ | Work
issues:
Report Upstream: N/A |
Reviewers:
Authors: |
Merged in:
Dependencies: |
Stopgaps: #12710
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Changes (by dsm):
* status: needs_review => needs_work
Comment:
The patch does seem to eliminate the original bug for me, but there's
still some strangeness for different _extend methods:
{{{
sage: set_random_seed(0)
sage: from sage.ext.multi_modular import MultiModularBasis_base
sage: m = MultiModularBasis_base(0);
sage: m._extend_moduli(100)
sage: len(m), len(set(m))
(101, 99)
sage: [k for k in m if list(m).count(k) > 1]
[30859, 3217, 30859, 3217]
}}}
{{{
sage: set_random_seed(1)
sage: from sage.ext.multi_modular import MultiModularBasis_base
sage: m = MultiModularBasis_base(0);
sage: m._extend_moduli_to_count(100)
100
sage: len(m), len(set(m))
(100, 97)
sage: [k for k in m if list(m).count(k) > 1]
[4001, 5309, 23293, 4001, 23293, 5309]
}}}
So I think that two of the three _extend methods still don't give results
that I'd expect.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11358#comment:21>
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