#18613: Errors with is_isomorphic() for trivial cones
-------------------------------------+-------------------------------------
Reporter: mjo | Owner:
Type: defect | Status: needs_work
Priority: major | Milestone: sage-6.9
Component: geometry | Resolution:
Keywords: cone | Merged in:
Authors: Andrey | Reviewers:
Novoseltsev | Work issues:
Report Upstream: N/A | Commit:
Branch: | c02beeea863a04328e39dd88b476ee1cfdc8fefa
u/novoselt/errors_with_is_isomorphic___for_trivial_cones| Stopgaps:
Dependencies: |
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Comment (by novoselt):
Yet another bug uncovered by this ticket. In clean 6.9.beta0 I get
{{{
sage: sage: polytope = LatticePolytope(
....: ...
[(-3,0,-1,-1),(-1,2,-1,-1),(0,-1,0,0),(0,0,0,1),(0,0,1,0),
....: ... (0,1,0,0),(0,2,-1,-1),(1,0,0,0),(2,0,-1,-1)])
sage: sage: coarse_fan = FaceFan(polytope)
sage: sage: P2 = toric_varieties.P2()
sage: sage: proj24 = matrix([[0,0],[1,0],[0,0],[0,1]])
sage: proj24
[0 0]
[1 0]
[0 0]
[0 1]
sage: proj24.pivots()
(0, 1)
sage: sage: fm = FanMorphism(proj24, coarse_fan, P2.fan(),
subdivide=True)
sage: fm.matrix()
[0 0]
[1 0]
[0 0]
[0 1]
sage: fm.matrix().pivots()
(0, 1, 2, 4)
}}}
so pivots are obviously screwed up somewhere. With my changes this affects
the rank computation as well. Now to figure out the fix...
--
Ticket URL: <http://trac.sagemath.org/ticket/18613#comment:15>
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