dualCone -- computes the dual Cone

i1 : C = posHull matrix {{1,2},{2,1}}

o1 = {ambient dimension => 2           }
      dimension of lineality space => 0
      dimension of the cone => 2
      number of facets => 2
      number of rays => 2

o1 : Cone

i2 : Cv = dualCone C

o2 = {ambient dimension => 2           }
      dimension of lineality space => 0
      dimension of the cone => 2
      number of facets => 2
      number of rays => 2

o2 : Cone

i3 : rays Cv

o3 = | 2  -1 |
     | -1 2  |

              2        2
o3 : Matrix ZZ  <--- ZZ