#18373: special resultants ``composed_op``
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Reporter: pernici | Owner:
Type: | Status: new
enhancement | Milestone: sage-duplicate/invalid/wontfix
Priority: major | Resolution:
Component: algebra | Merged in:
Keywords: | Reviewers:
Authors: | Work issues:
Report Upstream: N/A | Commit:
Branch: | Stopgaps:
Dependencies: |
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Changes (by pernici):
* commit: add79ac36e8eac6ae522e94b03f2ec9e776d8ee8 =>
* branch: u/pernici/ticket/18373 =>
* milestone: sage-6.7 => sage-duplicate/invalid/wontfix
Old description:
> added ``composed_op``, using the algorithm in
> A. Bostan, P. Flajolet, B. Salvy and E. Schost,
> "Fast Computation of special resultants",
> Journal of Symbolic Computation 41 (2006), 1-29
>
> These special resultants are useful to compute the minimal polynomials,
> see #18242
>
> For instance
>
> {{{
> sage: p1 = minpoly(cos(pi/43))
> sage: p2 = minpoly(cos(pi/47))
> sage: time r1 = p1.composed_op(p2, '+')
> Wall time: 108 ms
> sage: time r2 = p1.composed_op(p2, '+', algorithm="resultant")
> Wall time: 52.3 s
> sage: r1 == r2.monic()
> True
> sage: r1.is_irreducible()
> True
> sage: r1.degree()
> 483
> }}}
> so `r1` is the minimal polynomial of `cos(pi/43) + cos(pi/47)`
New description:
--
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Ticket URL: <http://trac.sagemath.org/ticket/18373#comment:3>
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