#17695: Slightly fasten is_cyclotomic()
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Reporter: bruno | Owner:
Type: enhancement | Status: needs_review
Priority: minor | Milestone: sage-6.5
Component: number theory | Resolution:
Keywords: cyclotomic | Merged in:
polynomials | Reviewers:
Authors: Bruno Grenet | Work issues:
Report Upstream: N/A | Commit:
Branch: | f79eeaaa630b1bd966a25a2f7b0f7a5f1dda3378
u/bruno/slightly_fasten_is_cyclotomic__| Stopgaps:
Dependencies: |
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Comment (by bruno):
Replying to [comment:10 vdelecroix]:
> Replying to [comment:9 bruno]:
> > For concreteness, what do you propose to do now? If I understand
correctly, you propose to wait for #17631 and then make `is_cyclotomic()`
directly call the pari functions, and not introduce the tiny change I
made? I am fine with that, just wanted to be sure!
>
> For now, we can already do the thing I proposed with the gp interface
(and return the certificate instead of `True`/`False`). And we can also
add a `TODO` section in the documentation saying that we should move to
the pari interface as soon as #17631 is ready.
I am not sure to agree since it actually makes the function slower:
{{{#!python
sage: p = cyclotomic_polynomial(150)
sage: %timeit p.is_cyclotomic()
100 loops, best of 3: 2.75 ms per loop
sage: %timeit p._gp_().poliscyclo()
100 loops, best of 3: 3.96 ms per loop
}}}
As an aside, isn't it a problem for a method named `is_cyclotomic()` to
return an integer rather than a boolean? Of course, the certificate is
interesting to have, and one can still test with `is_cyclotomic()` as
before. It is just that I expect a method `is_...()` to return a boolean.
Maybe I am wrong...
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Ticket URL: <http://trac.sagemath.org/ticket/17695#comment:11>
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