function xyz=emisfera(r) %# A radius value is given
[x,y,z] = sphere;      %# Makes a 21-by-21 point sphere
x = x(11:end,:);       %# Keep top 11 x points
y = y(11:end,:);       %# Keep top 11 y points
z = z(11:end,:);       %# Keep top 11 z points
xyz = [r*x,r*y,r*z];