On Wed, Feb 27, 2019 at 1:02 PM Daniel Krenn <kr...@aon.at> wrote: > > Say we have > > sage: P = polytopes.simplex(2) > sage: P.faces(1) > (<0,1>, <0,2>, <1,2>) > > Is there an easy way in SageMath to compute the in- or outward surface > normal vector of these faces of P? (in contrast to doing it all from > scratch). If not, are there methods that might help, so that not > everything needs to be built from scratch? > > Note: What I search for, is a method that works for a general compact > polyghedron in any dimension and their faces of dimension-1.
In the full-dimensional case, say, P=polytopes.cube() P.inequalities() is more or less what you need (as they correspond to the facets, a.k.a. faces of codimension 1) e.g. P.inequalities()[0].vector()[1:] (0, 0, -1) is one of the 6 normal vectors. I suppose in non-full-dimensional case you still can use P.inequalities() as above, projecting them on the affine hull of P. Dima > > Best > > Daniel > > -- > You received this message because you are subscribed to the Google Groups > "sage-support" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to sage-support+unsubscr...@googlegroups.com. > To post to this group, send email to sage-support@googlegroups.com. > Visit this group at https://groups.google.com/group/sage-support. > For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To post to this group, send email to sage-support@googlegroups.com. Visit this group at https://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/d/optout.
