#17366: for multivariate polynomial rings, degree method should convert its
argument
-------------------------------------+-------------------------------------
Reporter: jhpalmieri | Owner:
Type: defect | Status: needs_review
Priority: major | Milestone: sage-6.5
Component: algebra | Resolution:
Keywords: | Merged in:
Authors: John Palmieri | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/jhpalmieri/degree_convert_element| 65e68e16e2bffc1fcfb6fe5328c6ca5c0695ddbc
Dependencies: | Stopgaps:
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Comment (by jhpalmieri):
Making this change in `multi_polynomial_libsingular.pyx` breaks a doctest
which is supposed to test exactly this:
{{{
The following example is inspired by trac 11652::
sage: R.<p,q,t> = ZZ[]
sage: poly = p+q^2+t^3
sage: poly = poly.polynomial(t)[0]
sage: poly
q^2 + p
There is no canonical coercion from ``R`` to the parent of
``poly``, so
this doesn't work::
sage: poly.degree(q)
Traceback (most recent call last):
...
TypeError: argument must canonically coerce to parent
}}}
At #11652, there was some debate about this, and the conclusion was that
coercion was appropriate, not conversion. (In the above example, q
obviously converts to an element of the parent of `poly`, but there is no
coercion.)
--
Ticket URL: <http://trac.sagemath.org/ticket/17366#comment:8>
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