#13191: Construct a 2-d fan from rays only
--------------------------------+-------------------------------------------
Reporter: vbraun | Owner: AlexGhitza
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-5.2
Component: geometry | Resolution:
Keywords: toric | Work issues: completeness bug
Report Upstream: N/A | Reviewers: Andrey Novoseltsev
Authors: Volker Braun | Merged in:
Dependencies: #12544 | Stopgaps:
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Changes (by novoselt):
* work_issues: => completeness bug
Comment:
{{{
sage: Fan2d([(0,1)])
Rational polyhedral fan in 2-d lattice N
sage: _.is_complete()
True
}}}
Selecting distinct rays is a bit convoluted, but especially strange is
repeating this selection on sorted rays which are already distinct just to
trigger the complete removal of a single ray. How about something like
this:
{{{
...
n = len(rays)
if n == 1 or n == 2 and rays[0] == -rays[1]:
cones = [(i, ) for i in range(n)]
return RationalPolyhedralFan(cones, rays, lattice, False)
import math
sorted_rays = sorted(...)
cones = []
...
# there are definitely some 2-d cones now
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13191#comment:6>
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