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OldPolyhedra :: vertexFacetMatrix

vertexFacetMatrix -- computes the vertex-facet-relations matrix

Synopsis

Description

vertexFacetMatrix computes the matrix M where the columns are indexed by the facets and the rows are indexed by the vertices of P and has 1 as an entry if the corresponding facet contains this vertex and 0 otherwise.

i1 : P = cyclicPolytope(3,5)

o1 = {ambient dimension => 3           }
      dimension of lineality space => 0
      dimension of polyhedron => 3
      number of facets => 6
      number of rays => 0
      number of vertices => 5

o1 : Polyhedron
i2 : vertexFacetMatrix P

o2 = | 0 1 2 3 4 5 6 |
     | 1 1 1 1 0 0 1 |
     | 2 1 0 0 0 1 1 |
     | 3 1 1 0 1 1 0 |
     | 4 0 1 1 1 0 0 |
     | 5 0 0 1 1 1 1 |

              6        7
o2 : Matrix ZZ  <--- ZZ

Ways to use vertexFacetMatrix :

For the programmer

The object vertexFacetMatrix is a method function.