#6238: possible failure in is_planar(set_embedding=True, set_pos=False)
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Reporter: ncalexan | Owner: rlm
Type: defect | Status: new
Priority: major | Milestone: sage-4.0.2
Component: graph theory | Keywords:
Reviewer: | Author:
Merged: |
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{{{
sage: pari('v'), pari('w')
(v, w)
sage: w = QQ['w'].0
sage: v = QQ['w']['v'].0
sage: f = v^3 - (w^7 + w + 1)
sage: rts = list(set(f.discriminant().roots(QQbar, multiplicities=False)))
sage: rts = map(CDF, rts)
sage: xs = map(real_part, rts)
sage: ys = map(imag_part, rts)
sage: import delaunay
sage: DT = delaunay.Triangulation(xs, ys)
sage: G = Graph(DT.node_graph())
sage: G.set_pos(dict(enumerate(zip(xs, ys))))
sage: G.is_planar(set_embedding=True, set_pos=False)
True
sage: G.get_embedding()
{0: [2, 3, 6],
1: [5, 4, 2],
2: [6, 1, 4, 5, 3, 0],
3: [0, 2, 5],
4: [2, 1],
5: [3, 2, 1],
6: [0, 2]}
}}}
The first face does not have vertices in clockwise order. At least, not
for me :) Hard to see without show-ing the graph.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/6238>
Sage <http://sagemath.org/>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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