# Singular

#### D.13.2.28 isCanonical

Procedure from library `polymake.lib` (see polymake_lib).

Usage:
isCanonical(p); p polytope

Return:
1, if p has exactly one interior lattice point; 0 otherwise

Example:
 ```LIB "polymake.lib"; ==> Welcome to polymake version ==> Copyright (c) 1997-2015 ==> Ewgenij Gawrilow, Michael Joswig (TU Darmstadt) ==> http://www.polymake.org intmat M[6][4]= 1,1,1,2, 1,-1,-1,-2, 1,1,0,0, 1,-1,0,0, 1,0,1,0, 1,0,-1,0; polytope p = polytopeViaPoints(M); isCanonical(p); ==> polymake: used package ppl ==> The Parma Polyhedra Library (PPL): A C++ library for convex polyhedra ==> and other numerical abstractions. ==> http://www.cs.unipr.it/ppl/ ==> ==> polymake: WARNING: rule latte.integer_points: N_INTERIOR_LATTICE_POINTS \ : CONE_AMBIENT_DIM, CONE_DIM, FACETS | INEQUALITIES failed: can't parse o\ utput from LattE's 'count' ==> polymake: WARNING: rule latte.ehrhartpoly: LATTICE, EHRHART_POLYNOMIAL_C\ OEFF : CONE_AMBIENT_DIM, FACETS | INEQUALITIES failed: could not parse ou\ tput from latte at /usr/share/polymake/apps/polytope/rules/latte.rules li\ ne 231. ==> 1 isReflexive(p); ==> 0 intmat N[3][3]= 1,2,0, 1,0,2, 1,-2,-2; polytope q = polytopeViaPoints(N); isCanonical(q); ==> polymake: WARNING: rule latte.integer_points: N_INTERIOR_LATTICE_POINTS \ : CONE_AMBIENT_DIM, CONE_DIM, FACETS | INEQUALITIES failed: can't parse o\ utput from LattE's 'count' ==> polymake: WARNING: rule latte.ehrhartpoly: LATTICE, EHRHART_POLYNOMIAL_C\ OEFF : CONE_AMBIENT_DIM, FACETS | INEQUALITIES failed: could not parse ou\ tput from latte at /usr/share/polymake/apps/polytope/rules/latte.rules li\ ne 231. ==> 0 ```