#20086: rational powers in ZZ[X] and QQ[X]
-------------------------------------+-------------------------------------
Reporter: cheuberg | Owner:
Type: defect | Status: needs_review
Priority: major | Milestone: sage-7.1
Component: basic arithmetic | Resolution:
Keywords: | Merged in:
Authors: Clemens | Reviewers: Benjamin Hackl
Heuberger, Vincent Delecroix | Work issues:
Report Upstream: N/A | Commit:
Branch: | c8350c631287dd71a9b79fb422d769a1e480cdc8
u/behackl/polynomial/rational- | Stopgaps:
powers |
Dependencies: |
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Comment (by vdelecroix):
Nope. This is actually working because of a bug see #20214 ;-(. What I
wrote in the generic `nth_root` should always be an infinite loop (because
of `u.nth_root(n)`).
One possibility:
- make it work when `u.is_one()` is `True` (or more generally when
`u.multiplicative_order()` is finite)
- raise an error if `u` is not in the above case and there are some non
trivial factors
The aim of the second item is that in children classes (like polynomials)
you might want to do
{{{
def nth_root(self, n):
if self.degree() <= 0:
# factorize unit using base ring method
XXX
else:
return super(XXX).nth_root(self, n)
}}}
--
Ticket URL: <http://trac.sagemath.org/ticket/20086#comment:38>
Sage <http://www.sagemath.org>
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