#16464: cyclotomic_cosets for any finite ring
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Reporter: | Owner:
vdelecroix | Status: needs_info
Type: | Milestone: sage-6.3
enhancement | Resolution:
Priority: major | Merged in:
Component: | Reviewers:
number theory | Work issues:
Keywords: | Commit:
Authors: | b07ad014b69fc326233a570e41fbdad93402049c
Vincent Delecroix | Stopgaps:
Report Upstream: N/A |
Branch: |
public/16464 |
Dependencies: |
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Comment (by vdelecroix):
Replying to [comment:12 ncohen]:
> A new commit, with two questions :
>
> 1)
>
> {{{
> + if n <= 2 or not n.is_prime():
> + raise ValueError("the argument n must be an odd prime")
> }}}
>
> Why don't you test that `n` is odd ?
Hum. If n is prime and not 2 it is necessarily odd.
> 2) Why would this be allowed ? It really does NOT have the same
behaviour.
>
> {{{
> - n = max(S1+S2)+1
> - if not(is_a_splitting(S1,S2,n)):
> + n = len(S1) + len(S2) + 1
> + if not is_a_splitting(S1,S2,n):
> }}}
It does. `is_a_splitting(S1,S2,n)` answers `True` if the input is a
partition `(S1,S2)` of `{1,...,n-1}` (+ a condition on the partition). So
I just changed the code to avoid the concatenation and the max.
Do you agree?
--
Ticket URL: <http://trac.sagemath.org/ticket/16464#comment:15>
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