4.23 fan

In order to use convex objects in Singular, Singular has to be build from sources together with gfanlib, a C++ library for convex geometry by Anders N. Jensen. Please check the readme file for installation instructions.

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

4.23.1 fan related functions