#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 | Keywords: matrix multiplication,
multi-modular, integers, ZZ
Work_issues: | Upstream: N/A
Reviewer: | Author:
Merged: | Dependencies:
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Comment(by was):
*ping* why is this ticket dead? It seems very, very important, but
everybody forgot about it a year ago?!
Replying to [comment:15 tomc]:
> Note that the situation we are discussing is very unlikely to ever occur
in practice, as the default
> values of _lbound and _ubound are repectively 2**10 and 2**15 and
> there are many primes in between 2**10 and 2**15.
This is completely false. There are hardly any primes in that range:
{{{
sage: len(prime_range(2^10,2^15))
3340
}}}
The linear algebra in Sage is currently very broken in practice, perhaps
due to various optimizations and re-implementations that have
fundamentally broken things. For example, I'm constantly hitting a
problem of "not enough primes" (see #10281), even for matrices over QQ.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11358#comment:17>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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