#18442: Implement a barycentric subdivision method for Polyhedron class
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Reporter: jipilab | Owner:
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-6.8
Component: geometry | Resolution:
Keywords: polytope, | Merged in:
barycentric subdivision | Reviewers:
Authors: Jean-Philippe | Work issues:
Labbé | Commit:
Report Upstream: N/A | 996a8a4205d9f959af8e4841e39d16f66a06fe92
Branch: | Stopgaps:
public/ticket/18442 |
Dependencies: |
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Comment (by jipilab):
The problem pointed out is created by the following behavior:
sage: P = polytopes.regular_polygon(5)
sage: a_vertex = P.vertices()[0]
sage: for facet in P.Hrepresentation():
print facet.contains(a_vertex), facet.interior_contains(a_vertex)
True False
True True
True False
True True
True True
sage: P = polytopes.regular_polygon(5, base_ring=RDF)
sage: a_vertex = P.vertices()[0]
sage: for facet in P.Hrepresentation():
print facet.contains(a_vertex), facet.interior_contains(a_vertex)
True True
True True
True True
True True
True True
The last behavior is indeed problematic since we can not recognize the
vertices by the containment using the specific methods. Is this a bug?
Basically, I would never really do computation in RDF using polytopes or
do it in very specific contexts. In the context of barycentric subdivision
also.
For the sake of this patch, perhaps taking a regular pentagon is not
ideal, although it aloud to show this problem.
I could simply replace this example with a square.
--
Ticket URL: <http://trac.sagemath.org/ticket/18442#comment:19>
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