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by xammy
13 Sep 2012, 14:14
Forum: Helpdesk
Topic: Testing for affine mapping between two polytopes
Replies: 1
Views: 3712

Testing for affine mapping between two polytopes

Hi,

is there any method (at best implemented in Polymake) that, given two polytopes P,Q, checks whether there exists an affine linear map pi with P = pi(Q)?
by xammy
13 Sep 2012, 14:12
Forum: Helpdesk
Topic: hypersimplex for special cases
Replies: 2
Views: 4841

Re: hypersimplex for special cases

Perfect! I'm happy now :)
by xammy
30 Aug 2012, 09:28
Forum: Helpdesk
Topic: hypersimplex for special cases
Replies: 2
Views: 4841

hypersimplex for special cases

Is there a specific reason why hypersimplex(0,d) and hypersimplex(d,d) are not allowed? Of course the resulting polytopes are just single points but I really "needed" them: For example, one can describe the even-parity polytope (convex hull of 0/1 points with even number of 1's) by a disju...
by xammy
29 May 2012, 12:58
Forum: Feature Requests
Topic: Wiki Request
Replies: 0
Views: 20948

Wiki Request

Hi everybody, I've written a small extension on extended formulations. Here is the data: Short description: A Polymake extension to compute slack factorizations from extended formulations and vice versa. Official link: https://github.com/xammy/polymake-extended-formulations/wiki Github code: https:/...
by xammy
16 Apr 2012, 08:18
Forum: Helpdesk
Topic: Creating a graph with edge properties
Replies: 7
Views: 9378

Re: Creating a graph with edge properties

Now multigraphs are implemented; ...
Very nice - I will start working on them as soon as I'm done with lots of other things! Thank you for the effort.
by xammy
28 Mar 2012, 16:58
Forum: Helpdesk
Topic: Creating a graph with edge properties
Replies: 7
Views: 9378

Re: Creating a graph with edge properties

Does graph::Graph allow parallel edges and loops?
Loops are allowed, but not parallel edges.
Then I have a problem indeed - without parallel edges not all matroid decompositions for the TU test extension may be displayed correctly.
by xammy
26 Mar 2012, 10:28
Forum: Helpdesk
Topic: Creating a graph with edge properties
Replies: 7
Views: 9378

Creating a graph with edge properties

Hi, I known how to create a new graph object visible in perl using the following code. perl::Object construct_graph(...) { Graph<> g(4); g.edge(0, 1); g.edge(1, 2); g.edge(2, 0); g.edge(0, 3); perl::Object result("graph::Graph<Undirected>"); result.take("ADJACENCY") << g; return ...
by xammy
08 Mar 2011, 14:40
Forum: Helpdesk
Topic: Passing integer by reference in extension
Replies: 3
Views: 5936

Re: Passing integer by reference in extension

Thank you for the helpful reply! I managed to get it working with perl::ListReturn. The only drawback is that there was another version of the routine which did not compute k (to save running time) which I removed now. But I think it's okay as the running time gain is not a lot.
by xammy
07 Mar 2011, 18:36
Forum: Helpdesk
Topic: Passing integer by reference in extension
Replies: 3
Views: 5936

Passing integer by reference in extension

Hello, I'm working on an extension and want to pass an integer argument by reference. I tried the following perl-glue code: UserFunction4perl("# Tests a given //matrix// for k-modularity, without certificates. It also computes k." "# @param Matrix<int> matrix" "# @param int&...

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