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--- news:release_2_11 [2011/12/21 16:44] – draft for new features in Release 2.11 herr
+++ news:release_2_11 [2019/07/04 09:21] (current) – mradons
@@ Line 1: / Line 1: @@
 ====== New Features in Release 2.11 ======
-Release date: December xx, 2011.
+Release date: December 23, 2011.
-  * new big object SymmetricPolytope
+Release 2.11 is now available on the [[download:start|Downloads]] page. Here are the most important new features:
-  * improved shared library handling\\ e.g. for the interface from sage and gap, see [[http://forum.polymake.org/viewtopic.php?f=8&t=182|discussion about dlopen]] in the forum.
+  * improved shared library handling
+  * new big object ''SymmetricPolytope''
+  * computation of linear symmetries via ''SymPol''
   * solves a number of issues arising from empty polytopes
   * multitude of minor editions and bugfixes
+==== Improved shared library handling ====
+The support for loading the shared library on demand (via dlopen) is now improved. It is no longer necessary to specify RTLD_GLOBAL, the correct symbol visibility of libpolymake and libperl is now set automatically during the initialization of //polymake::Main// (see also the [[http://forum.polymake.org/viewtopic.php?f=8&t=182|discussion]] in the forum).
+==== New object class: SymmetricPolytope ====
+Release 2.11 provides a new "big object" class ''SymmetricPolytope''. These objects are defined via their GENERATING_GROUP and the input either of GEN_POINTS (and GEN_INPUT_LINEALITY), or of GEN_INEQUALITIES (and GEN_EQUATIONS). The GENERATING_GROUP property takes a permutation group object ''group::GroupOfPolytope'' acting on the coordinates of the points, or the inequalities, respectively. Having defined a SymmetricPolytope one can ask for the orbits of its vertices and its facets. They are stored as a property of the GENERATING_GROUP. Here is a brief example:
+<code>
+$g=new group::GroupOfPolytope(GENERATORS=>[[1,2,0],[1,0,2]],DOMAIN=>$polytope::domain_OnCoords);
+$p=new SymmetricPolytope<Rational>(GEN_POINTS=>[[1,1,2,0],[1,1,0,0],[1,0,0,0]],GENERATING_GROUP=>$g);
+print $p->VERTICES;
+$p->VISUAL;
+print $p->GENERATING_GROUP->VERTICES_IN_ORBITS;
+print $p->GENERATING_GROUP->FACETS_IN_ORBITS;
+</code>
+==== Computing linear symmetries ====
+Thanks to the new interface to ''SymPol'', a ''C++'' tool to work with symmetric polyhedra written by [[http://www.math.uni-rostock.de/~rehn/index.html|Thomas Rehn]] and [[https://www.mathematik.uni-rostock.de/struktur/professuren-apl-prof/geometrie/people/achill/|Achill Schürmann]], ''polymake'' is now able to compute linear symmetries of polyhedra.
+<code>
+$p=new Polytope<Rational>(POINTS=>cube(3)->VERTICES);
+linear_symmetries($p,1);
+</code>
+The symmetry group is stored in the property GROUP of the polytope ''$p''. The second parameter means that we are interested either in the permutation group acting on the facets (=0), or on the vertices (=1), as in our example. Asking for the generators of the group acting on the vertices we obtain the following output:
+<code>
+polytope > print $p->GROUP->GENERATORS;
+4 2 6 1 5 3 7
+1 4 5 2 3 6 7
+6 5 4 3 2 1 0
+6 0 4 3 7 1 5
+</code>
+Another new feature is the computation of stabilizers of sets and vectors. For example, we can compute the subgroup of the linear symmetries of ''$p'' leaving the set {1,2} invariant:
+<code>
+$s12=new Set<Int>(1,2);
+$stab12=group::stabilizer_of_set($p->GROUP,$s12);
+print $stab1->GENERATORS;
+</code>