#10140: Base sage.geometry.cone on the Parma Polyhedra Library (PPL)
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Reporter: vbraun | Owner: mhampton
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-feature
Component: geometry | Keywords: ppl
Author: Volker Braun | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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Comment(by novoselt):
Wonderful speed gain! However, when do you expect PPL to become a standard
library? It is my impression that currently it is difficult to add new
standard packages and it is more likely to become an optional one for a
while. In which case there should be an option to use PPL, but its
presence should not affect work of toric geometry.
Little picks at the patch:
1. I don't see why it is necessary to remove the possibility of `Cone`
construction from a `Polyhedron`.
1. I think that new possible input `C_Polyhedron` should be documented in
the INPUT section rather than a note in the end.
1. Is it possible to make `C_Polyhedrons` immutable (on demand)?
1. I prefer all line generators to be put in the end of ray list for non-
strictly convex cones, if they were determined automatically. Because if
one works with faces of such a cone, then all these generators are the
same and, therefore, others are more "important". That's very minor, of
course.
1. I am trying to follow PEP8 style guide
http://www.python.org/dev/peps/pep-0008/ which says: When raising an
exception, use "raise `ValueError`('message')" instead of the older form
"raise `ValueError`, 'message'". New line 1167 tries to change this
recommended form to an old one ;-)
1. Looking at what you have done in facet normals, maybe we should change
`cone.dual_lattice()` method to always return ZZ^n^ if there is no dual
method for the lattice? Thinking of the class group situation, it seems
like a more sensible default.
1. I think cones should not be printed explicitly (i.e. using "print")
when `ValueError` is raised due to attempt to intersect cones in lattices
of different dimension. The reason is that maybe some users want to
intercept this exception and deal with it in their own way without showing
any output. Also, I think that the check should be done not for equality
of lattice dimensions, but for equality of lattices themselves, because
cones of different lattices should not be intersected.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10140#comment:2>
Sage <http://www.sagemath.org>
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