#10268: adding GiNaC method to simplify_rational
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Reporter: bgoodri | Owner: burcin
Type: enhancement | Status: needs_work
Priority: minor | Milestone: sage-4.6.2
Component: symbolics | Keywords:
Author: Ben Goodrich | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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Changes (by bgoodri):
* cc: was (added)
Comment:
Replying to [comment:5 burcin]: cc'ing William for clarification
> I haven't looked into the functionality in `normal.cpp` much, but one of
William's goals was to make it call Singular (or the Factory library) to
factor multivariate polynomials instead of the code in ginac. This library
generally performs much better and it is actively being developed.
Do you really want to do full factorization in `simplify_rational()`. I
think neither Maxima nor GiNaC do that, only square-free factorization and
gcd cancellation. We could add an option to do full factorization of the
numerator and denominator before returning. If so, would it make more
sense to first backport the functionality in factor.cpp from GiNaC 1.5.x
to the pynac fork than to code a pynac-libSingular link?
Also, I think this might be a bit separate from the issue I was hitting.
When I ran test.sage last night under trace() with the enter key wedged
down, by the morning it had called gcd() over 30,000 times and hadn't even
passed the rational expression to GiNaC yet. This is a waste because
GiNaC's normal() function was going to do 1 gcd cancellation anyway. So,
it seems what we need is an option to prevent sage from trying to find the
gcd of every subexpression.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10268#comment:6>
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