#10046: Polyhedron's incidence_matrix performs poorly on some numerical input
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Reporter: mhampton | Owner: mhampton
Type: defect | Status: needs_review
Priority: major | Milestone: sage-4.6.1
Component: geometry | Keywords:
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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Comment(by mhampton):
I disagree, and I would like to fix this problem. For rigorous
computation I don't trust numerical computation of convex hulls anyway,
unless there is some additional way to certify the correctness. The
numerical routines are important for having fast graphical output.
The current behavior is just terrible, and I think this is a real
improvement for lots of actual use cases.
To keep the main Polyhedron logic clean I will put in
_init_from_cdd_output as follows:
{{{
skip_to('H-representation')
self._Hrepresentation = Sequence([])
equations = cdd_linearities()
skip_to('begin')
l = cddout.pop(0).split()
assert self._ambient_dim == int(l[1])-1, "Different ambient
dimension?"
for i in range(int(l[0])):
l = cddout.pop(0)
data = cdd_convert(l)
if self._cdd_type == 'real':
normal_norm = vector(data[1:]).norm()
data = [x/normal_norm for x in data]
if i in equations:
Equation(self, data);
else:
Inequality(self, data);
}}}
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10046#comment:10>
Sage <http://www.sagemath.org>
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