division by 0

[anonymous]

Input for Voronoi:

points.push_back(point(1, 1)); points.push_back(point(3, 1)); points.push_back(point(1, 3)); points.push_back(point(3, 3)); points.push_back(point(-1, 1)); points.push_back(point(1, -1)); points.push_back(point(5, 1)); points.push_back(point(3, -1)); points.push_back(point(-1, 3)); points.push_back(point(1, 5)); points.push_back(point(5, 3)); points.push_back(point(3, 5)); VD vd; construct_voronoi(points.begin(), points.end(), &vd);

I get a division by 0. Is this normal? What are the restrictions on the points?