#11902: Fan subdivision should check rays
----------------------------------+-----------------------------------------
Reporter: vbraun | Owner: AlexGhitza
Type: defect | Status: new
Priority: major | Milestone: sage-4.7.3
Component: algebraic geometry | Keywords:
Work_issues: | Upstream: N/A
Reviewer: | Author:
Merged: | Dependencies:
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The following should raise an error:
{{{
sage: fan = toric_varieties.P2().fan()
sage: fan.subdivide(new_rays=[(0,0)])
Rational polyhedral fan in 2-d lattice N
}}}
Right now, you only fall on your face once you try to do something with
this "subdivided" fan:
{{{
sage: _.cones()
---------------------------------------------------------------------------
KeyError Traceback (most recent call
last)
/home/vbraun/Sage/EllipticFibration/<ipython console> in <module>()
/home/vbraun/Sage/sage/local/lib/python2.6/site-
packages/sage/geometry/fan.pyc in cones(self, dim, codim)
1744 if "_cones" not in self.__dict__:
1745 levels = [(e.element for e in level) # Generators
-> 1746 for level in
self.cone_lattice().level_sets()]
1747 levels.pop() # The very last level is this FAN, not
cone.
1748 # It seems that there is no reason to believe that the
order of
/home/vbraun/Sage/sage/local/lib/python2.6/site-
packages/sage/geometry/fan.pyc in cone_lattice(self)
1682 """
1683 if "_cone_lattice" not in self.__dict__:
-> 1684 self._compute_cone_lattice()
1685 return self._cone_lattice
1686
/home/vbraun/Sage/sage/local/lib/python2.6/site-
packages/sage/geometry/fan.pyc in _compute_cone_lattice(self)
1099 # Make sure that rays are in the beginning in proper
order
1100 head = [rays_to_index[()]] # Empty face
-> 1101 head.extend(rays_to_index[(n,)] for n in
range(self.nrays()))
1102 new_order = head + [n for n in new_order if n not in
head]
1103 # "Invert" this list to a dictionary
/home/vbraun/Sage/sage/local/lib/python2.6/site-
packages/sage/geometry/fan.pyc in <genexpr>((n,))
1099 # Make sure that rays are in the beginning in proper
order
1100 head = [rays_to_index[()]] # Empty face
-> 1101 head.extend(rays_to_index[(n,)] for n in
range(self.nrays()))
1102 new_order = head + [n for n in new_order if n not in
head]
1103 # "Invert" this list to a dictionary
KeyError: (3,)
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11902>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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