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by joswig
14 Feb 2019, 20:47
Forum: Helpdesk
Topic: Problems with tropical polytopes with rational vertices
Replies: 4
Views: 40

Re: Problems with tropical polytopes with rational vertices

Which version of polymake are you using? We just released version 3.3, and there it works. It is possible that in some older versions the types get messed up. Beware that the property POINTS takes a small object of type Matrix<TropicalNumber<Min>>. Object of type Rational should automatically conver...
by joswig
07 Feb 2019, 13:59
Forum: Helpdesk
Topic: Strugles with VERTICES_IN_FACETS
Replies: 2
Views: 61

Re: Strugles with VERTICES_IN_FACETS

My purpose is to compute a cone $c pointed at some vertex $v of a polytope $p, such that its rays are the affine hull of the facets of $p incident to $v, and such that $p itself is not contained in $c. Sorry, I do not understand what you want to compute. Do you want to compute the intersection of t...
by joswig
23 Sep 2018, 17:47
Forum: General Discussion
Topic: Math StackExchange Q&A - infinite family of self-dual polytopes
Replies: 1
Views: 6515

Re: Math StackExchange Q&A - infinite family of self-dual polytopes

Thanks for letting us now (and mentioning polymake). I like the Sierpinksi pattern!
by joswig
27 Aug 2018, 16:40
Forum: Helpdesk
Topic: Facets calculated on 2nd try (not on 1st try)
Replies: 1
Views: 7250

Re: Facets calculated on 2nd try (not on 1st try)

I looked into this, but I cannot reproduce your error. Sorry. Please install a version of polymake on your system, cf. https://polymake.org/doku.php/download/start . The shell.polymake.org version has a number of limitations and is proof-of-concept only. For instance, there is an upper limit on the ...
by joswig
25 Jul 2018, 22:57
Forum: Helpdesk
Topic: 2-codimensional tropical hypersurfaces
Replies: 1
Views: 1020

Re: 2-codimensional tropical hypersurfaces

Your input needs to be homogenized.
by joswig
04 Jun 2018, 14:03
Forum: Helpdesk
Topic: ERROR: no matching overloaded instance of...
Replies: 3
Views: 1330

Re: ERROR: no matching overloaded instance of...

I'm getting errors of the form ERROR: no matching overloaded instance of... a lot, and I'm not sure how to interpret them. To give a bit more context: polymake supports operator overloading and polymorphism. That is, the function to be called is not only determined by the name of the function but a...
by joswig
26 Feb 2018, 16:51
Forum: Helpdesk
Topic: Discrepancy in computing facets of a mixed integer program
Replies: 29
Views: 5087

Re: Discrepancy in computing facets of a mixed integer program

OK, I did one test with your example.

Code: Select all

polytope> $lp=lp2poly "/tmp/problem.lp";

Code: Select all

polytope> print $lp->LP->MINIMAL_VALUE; 2917698461538468882086/17303076923076959125

Code: Select all

polytope> print convert_to<Float>($lp->LP->MINIMAL_VALUE); 168.623099493198
So cplex seems to be right about the LP.
by joswig
26 Feb 2018, 16:46
Forum: Helpdesk
Topic: Discrepancy in computing facets of a mixed integer program
Replies: 29
Views: 5087

Re: Discrepancy in computing facets of a mixed integer program

In the meantime, assuming you have access to an MIP solver (and therefore an LP solver) at your end that can read in the files I provided in the OP, I would be really grateful if any of the polymake developers can verify if the discrepancy exists on 3.2. My OP is detailed enough to be able to repli...
by joswig
02 Feb 2018, 10:12
Forum: Helpdesk
Topic: Error when using projection command
Replies: 3
Views: 1848

Re: Error when using projection command

Please recall that projecting a polytope down by one dimension might (asymptotically) square the number of facets. Loosing nine dimension this might result in an enormous number of facets. As a side comment: exploiting the reverse is the idea behind the so-called "extended formulations"; see, e.g., ...
by joswig
23 Jan 2018, 20:42
Forum: General Discussion
Topic: Lattice points at the intersection of 3 hyperplanes
Replies: 10
Views: 4826

Re: Lattice points at the intersection of 3 hyperplanes

If you replace what obviously needs to be replaced in $p = new Polytope(INEQUALITIES=>{non-negativity constraints}, EQUATIONS=>{three hyperplanes}); print $p->LATTICE_POINTS; then this should do the trick. Several caveats: (1) depending on your hyperplanes the result may be unbounded. (2) Deciding w...

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