function art3(a,v)

x = v(:,1);
y = v(:,2);
z = v(:,3);

[i,j,v] = find(a);
E = [i,j];



figure(1)
hold on
clf
plot3(x,y,z,'o');
hold on
for i = 1:length(E)
  plot3(x(E(i,:))',y(E(i,:))',z(E(i,:))');
end

