Fan subdivision should check rays

[vbraun]

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,)

[novoselt]

Horrible! Will fix shortly.

[jdemeyer]

Milestone sage-4.7.3 deleted

[novoselt]

Happy holidays, Volker! Could you please check this one-liner?-)

[vbraun]

Sorry, forgot! Positive review!