#9094: is_square and sqrt for polynomials and fraction fields
-------------------------------+--------------------------------------------
Reporter: robertwb | Owner: AlexGhitza
Type: defect | Status: needs_work
Priority: major | Milestone: sage-4.4.4
Component: algebra | Keywords:
Author: Robert Bradshaw | Upstream: N/A
Reviewer: John Cremona | Merged:
Work_issues: doctest failure |
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Changes (by newvalueoldvalue):
* status: needs_review => needs_work
* reviewer: => John Cremona
* work_issues: => doctest failure
* author: => Robert Bradshaw
Comment:
Looks good (and useful). Patch applies fine to 4.4.3. I tested all
sage/rings and had one failure (in a new doctest, on 64-bit ubuntu):
{{{
File "/storage/jec/sage-4.4.3/devel/sage-
tests/sage/rings/polynomial/polynomial_element.pyx", line 1262:
sage: (9 * f^10 * g^4).sqrt() == 3 * f^5 * g^2
Expected:
True
Got:
False
}}}
I have never been happy about doctests using random elements, however
deterministic they are supposed to be.
I would have tested for self==0 at the start of the sqrt function, but
that case will be caught quickly anyway, so no problem.
I have been working on a patch to add both all= and extend= parameters to
the sqrt function for AA and QQbar, having found how awkward it is when
the parameters are not uniform across types. Would it be worth adding an
extend= parameter here, even if a NotImplementedError is raised when it is
needed (i.e. for sqrt of a non-square when extend=True)?
So: needs work because of the doctest failure; up to you whether to do
the extend= thing.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/9094#comment:2>
Sage <http://www.sagemath.org>
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