MATLAB Mathematics - SERC - Index of

Interpolation
In this example, V is a 13-by-3 matrix, the 13 rows are the coordinates of the 13
Voronoi vertices. The first row of V is a point at infinity. C is a 9-by-1 cell array,
where each cell in the array contains an index vector into V corresponding to
one of the 9 Voronoi cells. For example, the 9th cell of the Voronoi diagram is
C{9} = 2 3 4 5 6 7 8 9 10 11 12 13
If any index in a cell of the cell array is 1, then the corresponding Voronoi cell
contains the first point in V, a point at infinity. This means the Voronoi cell is
unbounded.
To view a bounded Voronoi cell, i.e., one that does not contain a point at
infinity, use the convhulln function to compute the vertices of the facets that
make up the Voronoi cell. Then use patch and other plot functions to generate
the figure. For example, this code plots the Voronoi cell defined by the 9th cell
in C:
X = V(C{9},:); % View 9th Voronoi cell.
K = convhulln(X);
figure
hold on
d = [1 2 3 1]; % Index into K
for i = 1:size(K,1)
j = K(i,d);
h(i)=patch(X(j,1),X(j,2),X(j,3),i,'FaceAlpha',0.9);
end
hold off
view(3)
axis equal
title('One cell of a Voronoi diagram')
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