#9972: Add fan morphisms
------------------------------------------------+---------------------------
Reporter: novoselt | Owner: mhampton
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-4.6.1
Component: geometry | Keywords:
Author: Andrey Novoseltsev, Volker Braun | Upstream: N/A
Reviewer: Volker Braun, Andrey Novoseltsev | Merged:
Work_issues: |
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Changes (by vbraun):
* status: needs_review => needs_work
Comment:
Ok now `image_cone` works but I can't compute the preimage:
{{{
sage: c = f.image_cone( Cone([(1,0),(0,1)]) )
sage: c
1-d cone of Rational polyhedral fan in 1-d lattice N
sage: f.preimage_cones(c)
---------------------------------------------------------------------------
TypeError Traceback (most recent call
last)
/home/vbraun/opt/sage-4.6/devel/sage-main/<ipython console> in <module>()
/home/vbraun/Sage/sage/local/lib/python2.6/site-
packages/sage/geometry/fan_morphism.pyc in preimage_cones(self, cone)
858 for dcone in dcones:
859 if
(possible_rays.issuperset(dcone.ambient_ray_indices())
--> 860 and
self.image_cone(dcone).is_face_of(cone)):
861 preimage_cones.append(dcone)
862 self._preimage_cones[cone] = preimage_cones
/home/vbraun/Sage/sage/local/lib/python2.6/site-
packages/sage/geometry/fan_morphism.pyc in image_cone(self, cone)
809 RISGIS = self._RISGIS()
810 CSGIS = set(reduce(operator.and_,
--> 811 (RISGIS[i] for i in
cone.ambient_ray_indices())))
812 image_cone =
codomain_fan.generating_cone(CSGIS.pop())
813 for i in CSGIS:
TypeError: reduce() of empty sequence with no initial value
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/9972#comment:51>
Sage <http://www.sagemath.org>
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