MATLAB Mathematics - SERC - Index of

2 Polynomials and Interpolation
7 3 1
5 7 1
7 4 3
4 7 8
2 6 1
6 5 1
4 6 2
6 4 8
6 7 5
7 6 8
Because the data is three-dimensional, the facets that make up the convex hull
are triangles. The 12 rows of C represent 12 triangles. The elements of C are
indices of points in X. For example, the first row, 3 1 5, means that the first
triangle has X(3,:), X(1,:), and X(5,:) as its vertices.
For three-dimensional convex hulls, you can use trisurf to plot the output.
However, using patch to plot the output gives you more control over the color
of the facets. Note that you cannot plot convhulln output for n > 3.
This code plots the convex hull by drawing the triangles as three-dimensional
patches:
figure, hold on
d = [1 2 3 1]; % Index into C column.
for i = 1:size(C,1) % Draw each triangle.
j= C(i,d); % Get the ith C to make a patch.
h(i)=patch(X(j,1),X(j,2),X(j,3),i,'FaceAlpha',0.9);
end
% 'FaceAlpha' is used to make it transparent.
hold off
view(3), axis equal, axis off
camorbit(90,-5); % To view it from another angle
title('Convex hull of a cube')
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