Changes between Initial Version and Version 2 of Ticket #29176
 Timestamp:
 03/19/20 14:55:32 (13 months ago)
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Ticket #29176

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toneeds_review

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Authors
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Jonathan Kliem
 Property Cc jipilab ghLaisRast added

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public/29176
 Property Keywords cdd incidence matrix added

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33b59112324e37dcbdab7706047e47cf9dbf5568

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Ticket #29176 – Description
initial v2 1 The following should give two nonempty regions: 1 We fix a bug that was exposed computing an inexact Voronoi Diagram (see below). 2 3 `cdd` already computes the incidence matrix, we expose it in this ticket. 4 5 When deciding whether or not a vertex lies on a hyperplane for inexact polyhedra, we allow numerical noise up to absolute value of `1e6`. This might be a bad choice depending on the size of the polyhedron as witnessed in the following example: 6 7 {{{ 8 9 sage: e = [[11582947.657000002, 5374.38, 4177.06, 1.0], [11562795.9322, 5373.62, 4168.38, 1.0]] 10 sage: p = Polyhedron(ieqs=e); p 11 A 3dimensional polyhedron in RDF^3 defined as the convex hull of 1 vertex, 2 rays, 1 line 12 sage: p.incidence_matrix() 13 [0 0] 14 [0 0] 15 [0 1] 16 [0 0] 17 }}} 18 19 Setting the cache of incidence matrix to the matrix that `cdd` already computed for us produces the correct output: 20 21 {{{ 22 sage: p.incidence_matrix() 23 [1 1] 24 [1 0] 25 [0 1] 26 [1 1] 27 }}} 28 29 This fixes the error reported here: 30 31 https://ask.sagemath.org/question/49749/voronoidiagramreturnsemptyregions/ 32 33 The following should give two nonempty regions 2 34 3 35 {{{ … … 11 43 }}} 12 44 13 This way reported here:45 With this ticket we obtain: 14 46 15 https://ask.sagemath.org/question/49749/voronoidiagramreturnsemptyregions/ 47 {{{ 48 sage: R 49 {P(2687.19000000000, 2088.53000000000): A 2dimensional polyhedron in RDF^2 defined as the convex hull of 1 vertex, 1 ray, 1 line, 50 P(2686.81000000000, 2084.19000000000): A 2dimensional polyhedron in RDF^2 defined as the convex hull of 1 vertex, 1 ray, 1 line} 51 }}}