x and y coordinates of nodes of the voronoi mosaic. Each node is a
circumcircle center of some triangle from the Delaunay triangulation.
node
logical vector, indicating real nodes of the voronoi
mosaic. These nodes are the centers of circumcircles of triangles with
positive area of the delaunay triangulation.
If node[i]=FALSE, (c[i],x[i]
n1,n2,n3
indices of neighbour nodes. Negative indices indicate
dummy points as neighbours.