#9337: Add toric divisors
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Reporter: vbraun | Owner: AlexGhitza
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-4.6
Component: algebraic geometry | Keywords:
Author: Volker Braun | Upstream: N/A
Reviewer: Andrey Novoseltsev | Merged:
Work_issues: |
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Changes (by vbraun):
* status: needs_work => needs_review
* work_issues: doctest failures =>
Comment:
I fixed the doctests, that was just a minor issue. Thanks for catching it!
The divisor code already assumes at places that the divisor is reduced (we
should probably call this "collected", but I'll stick with it for now),
for example in the original code to extract the coefficient. In general I
think allowing unreduced divisors is going to be a huge pitfall for future
contributors as well as a performance impediment. If one really wanted
non-reduced divisors then one needs a flag to remember whether one already
did the reduction to avoid doing it over and over. On a final word of
warning:
{{{
sage: FormalSum([[1,2],[1,2]],reduce=False) == FormalSum([[2,2]])
False
}}}
The `reduce()` method is inherited from `FormalSum`, there is nothing more
to it. We could add a base class `ReducedFormalSum` without this method if
it bugs you, but I think thats not worth the effort.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/9337#comment:50>
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