From 37a6f281cfd5700ceb23e078f7beeddde5b1d862 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Fr=C3=A9d=C3=A9ric=20Chapoton?= Date: Tue, 16 Dec 2014 02:37:18 +0100 Subject: [PATCH] trac #17474 adding double edges when non-generic form --- src/sage/geometry/polyhedron/base.py | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/src/sage/geometry/polyhedron/base.py b/src/sage/geometry/polyhedron/base.py index 66f1cde4680..c9c6bc7b8d0 100644 --- a/src/sage/geometry/polyhedron/base.py +++ b/src/sage/geometry/polyhedron/base.py @@ -3290,7 +3290,10 @@ def vertex_digraph(self, f, increasing=False): - ``increasing`` -- boolean (default ``False``) whether to orient edges in the increasing direction instead. - By default, an edge is oriented from `v` to `w` if `f(v-w) > 0`. + By default, an edge is oriented from `v` to `w` if + `f(v-w) \geq 0`. + + If `f(v)=f(w)`, then two opposite edges are created. EXAMPLES:: @@ -3309,7 +3312,7 @@ def vertex_digraph(self, f, increasing=False): for j in range(self.n_vertices()): vj = self.Vrepresentation(j) for vi in vj.neighbors(): - if (vi.vector() - vj.vector()).dot_product(f) > 0: + if (vi.vector() - vj.vector()).dot_product(f) >= 0: dg.add_edge(vi, vj) return dg