#15790: GCD of sparse univariate polynomials over ZZ
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Reporter: bruno | Owner:
Type: defect | Status: needs_review
Priority: minor | Milestone: sage-6.4
Component: basic arithmetic | Resolution:
Keywords: sparse | Merged in:
polynomial, gcd | Reviewers:
Authors: Bruno Grenet | Work issues:
Report Upstream: N/A | Commit:
Branch: | ec2ef11336040e95c8cdf1bed7523006747b5ab1
u/bruno/gcd_of_sparse_univariate_polynomials_over_zz| Stopgaps:
Dependencies: |
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Comment (by bruno):
Replying to [comment:15 tscrim]:
> Do you have a heuristic for determining when one algorithm is faster
than another (when the base ring is `ZZ`)? It doesn't have to be a
particularly good one, but considering the time differences you're
getting, it seems like we should have some automatic choice of algorithm.
I don't have one. Based on the comments on
https://groups.google.com/forum/#!topic/sage-devel/6qhW90dgd1k, I add the
possibility for the "dense" algorithm to use NTL instead of FLINT. After
some tests, I chose a heuristic for using NTL rather than FLINT
(basically, FLINT is faster for low-degree polynomials and ''not-too-
sparse'' ones). Then the "dense" algorithm is almost always faster than
"pseudo-division" but for some very specific examples (I haven't been able
to build other ones): `gcd(x^N-1,x^M-1)` with both `N` and `M` pretty
large. An the ratio is not hundreds anymore, but approx. 10.
--
Ticket URL: <http://trac.sagemath.org/ticket/15790#comment:17>
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