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by joswig
21 Jun 2013, 09:23
Forum: Helpdesk
Topic: Check, if inequality induces a facet
Replies: 2
Views: 6745

Re: Check, if inequality induces a facet

If a given inequality is a facet of the feasible region can be decided by a linear program. This is dual to deciding whether one point from a set of points is a vertex of the convex hull. That latter problem is equivalent to deciding whether or not there is a hyperplane which separates that one poin...
by joswig
05 May 2013, 22:50
Forum: Helpdesk
Topic: Voronoi Tessellation with "cdd" and "beneath_beyond"
Replies: 9
Views: 10898

Re: Voronoi Tessellation with "cdd" and "beneath_beyond"

There is one facet per point plus one extra facet for the FAR_FACE (in this case the FAR_FACE is a facet). But you do not have to worry about lifting. polytope > my $points=new Matrix<Rational>([[1,-1,-1],[1,1,-1],[1,-1,1],[1,1,1],[1,0,0]]); $vd=new VoronoiDiagram(SITES=>$points); prefer_now "b...
by joswig
05 May 2013, 11:45
Forum: Helpdesk
Topic: Voronoi Tessellation with "cdd" and "beneath_beyond"
Replies: 9
Views: 10898

Re: Voronoi Tessellation with "cdd" and "beneath_beyond"

Ewgenij's recommendation polytope > $Verbose::rules=3; polytope > my $points=new Matrix<Rational>([[1,-1,-1],[1,1,-1],[1,-1,1],[1,1,1],[1,0,0]]); $p=new Polytope<Rational>(POINTS=>$points); prefer_now "beneath_beyond";$p->DUAL_GRAPH->ADJACENCY; save($p,"OUTPUT.xml"); results in r...
by joswig
02 May 2013, 16:51
Forum: Helpdesk
Topic: Partial results from FACETS
Replies: 1
Views: 4605

Re: Partial results from FACETS

Unfortunately, the current setup does not allow for much logging information for the convex hull computations. I clearly understand that this is desirable though. We started to look into some possibilities. Stay tuned. We do not allow partial output. This has to do with the overall design of polymak...
by joswig
27 Mar 2013, 19:34
Forum: Helpdesk
Topic: Homology
Replies: 5
Views: 6856

Re: Homology

The data type of the HOMOLOGY property is a bit special; actually it is Array<HomologyGroup<Integer>>. This is how you can address an individual group: topaz > $rp2=projective_plane(); topaz > print $rp2->HOMOLOGY->[1]; {(2 1)} 0 Each homology group more or less works like an array (of a pair and a ...
by joswig
26 Mar 2013, 23:44
Forum: Helpdesk
Topic: Problems with the visualisation of a fan
Replies: 2
Views: 4414

Re: Problems with the visualisation of a fan

when I visualise a fan via jreality, the output has way more cones than I expect. It seems that cones with more than three rays are subdivided, so that each cone has only three rays. Is that a feature or a bug? With the jReality window active press "alt-shift-left", which opens an extra p...
by joswig
24 Mar 2013, 22:08
Forum: Helpdesk
Topic: lrs_alloc_dat(NULL) -> segfault
Replies: 1
Views: 3707

Re: lrs_alloc_dat(NULL) -> segfault

It seems you are using a version of lrslib other than the one shipped with polymake. Your patch is not necessary for polymake's lrslib. The polymake version fixes a few glitches of the original.
by joswig
10 Mar 2013, 12:28
Forum: Helpdesk
Topic: does SymmetricFan work?
Replies: 1
Views: 3660

Re: does SymmetricFan work?

Please give your complete code example. I suspect that LINEALITY_SPACE is missing in your input. RAYS only do not work.
by joswig
07 Mar 2013, 23:35
Forum: Helpdesk
Topic: Vertex labels vs indices
Replies: 3
Views: 5708

Re: Vertex labels vs indices

What about the following? topaz > $sc=new SimplicialComplex(INPUT_FACES=>[[5,6,8],[6,8]]); topaz > print rows_labeled($sc->FACETS,undef,$sc->VERTEX_INDICES); 0:5 6 8 The second parameter "undef" can be replaced by something meaningful if you also want to give names to the facets.
by joswig
13 Feb 2013, 10:46
Forum: Helpdesk
Topic: compute volume using callable library
Replies: 8
Views: 8770

Re: compute volume using callable library

Must I always use Polytope<Rational>? Well, if you want to get exact results: yes. However, I should also point out that there are other exact data types, such as QuadraticExtension<Rational>. The data type Polytope<Float> must be used with care since the combinatorics of such polytopes might not b...

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