# How to draw a ball by plot3?

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Xizeng Feng on 18 Feb 2022
Answered: J. Alex Lee on 28 Oct 2022
I am learning the MATLAB,

DGM on 19 Feb 2022
Edited: DGM on 19 Feb 2022
I choose to assume that a request to plot a solid volume with a line/point plotting tool should suggest that the usage of the term "ball" is informal and that a spherical shell is an acceptable interpretation of the wording:
nturns = 20;
pointsperturn = 50;
r = 1;
th = linspace(0,2*pi*nturns,pointsperturn*nturns);
phi = linspace(-pi/2,pi/2,pointsperturn*nturns);
[x y z] = sph2cart(th,phi,r);
plot3(x,y,z)
axis equal
grid on Xizeng Feng on 19 Feb 2022
thank you very much!

KSSV on 18 Feb 2022
m = 100; n = 100; p = 100 ;
[X,Y,Z] = ndgrid(-m:m,-n:n,-p:p) ;
x = X(:) ;
y = Y(:) ;
z = Z(:) ;
r = sqrt(x.^2+y.^2+z.^2) ;
idx = r <= 10 ;
plot3(x(idx),y(idx),z(idx),'.r')
axis equal Xizeng Feng on 19 Feb 2022
like this for example. J. Alex Lee on 28 Oct 2022
like this? but it doesn't use plot3
[x,y,z] = sphere(64);
p = surf(x,y,z,"FaceColor","interp","EdgeColor","none");
p.CData = rand(size(p.ZData));
colormap gray
axis equal
lighting phong
camorbit(60,0)
axis off 