Singular Manual: fan

| ## 4.25 fan In order to use convex objects in Singular, Singular uses gfanlib, a C++ library for convex geometry by Anders N. Jensen. Please check the readme file for installation instructions. The library gfan_lib provides this C++ library and an interface to it. Some functions require `polymake`: polymake_lib provides an interface to it. A polyhedral fan is a collection of cones closed under taking intersections and faces.
      fan f;                              // ambient dim 0, no cones, lineality
                                          // space = ambient space
      fan f = emptyFan(int n);            // ambient dim = n, no cones,
                                          // symmetry subgroup = <e>
      fan f = n;                          // synonymous convenience method for
                                          // 'fan f = emptyFan(n)'
      fan f = emptyFan(
                     optional intmat G);  // symmetry group generated by rows of
                                          // G; ambient dim = number of columns
                                          // of G
                // Here a row r = r_1, ...r_n represents the permutation
                // which takes i to r_i. SINGULAR will check for the validity
                // of the provided rows, i.e. whether {r_1,...,r_n} = {1,...,n}
      fan f = fullFan(int n);             // ambient dim = n, the fan consists of
                                          // one cone which equals the ambient
                                          // space, symmetry subgroup = <e>
      fan f = fullFan(
                     optional intmat G);  // symmetry group generated by rows of
                                          // G; ambient dim = number of columns
                                          // of G; the fan consists of one cone
                                          // which equals the ambient space
See also gfan_lib.

User manual for Singular version 4-2-0p1, 2020, generated by texi2html.