How to plot sphere in sphere coordinates?

Question

Niklas Kurz 2020-10-18

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/618008-how-to-plot-sphere-in-sphere-coordinates

评论： Bruno Luong 2020-10-21

I'm just trying to plot known sphere coordinates:

function sphere(r)
phi = linspace(0,2*pi);
theta = linspace(0,pi);
x = r*cos(phi).*sin(theta);
y = r*sin(phi).*sin(theta);
z = r*cos(theta);
plot3(x,y,z)
end

However this isn't doing the trick. What have I mathematically confounded?

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Answer 1

J. Alex Lee 2020-10-19

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https://ww2.mathworks.cn/matlabcentral/answers/618008-how-to-plot-sphere-in-sphere-coordinates#answer_517928

在 MATLAB Online 中打开

Your problem is not with conversion or plotting, but defining the coordinates that you want...

[phi,theta] = meshgrid(linspace(0,2*pi),linspace(0,pi));

Also if you didn't know:

https://www.mathworks.com/help/matlab/ref/sph2cart.html

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Niklas Kurz 2020-10-21

yea, but I wanted to go through the rough way ;)

You could have said additionally that I need to swap plot3(x,y,z) with mesh(x,y,z), but all in all you've been nudging me in the right direction. Thx

J. Alex Lee 2020-10-21

在 MATLAB Online 中打开

sure thing. if you decide you don't want the rough way and you haven't seen it, check

https://www.mathworks.com/help/matlab/ref/sphere.html

[X,Y,Z] = r*sphere(n)
mesh(X,Y,Z)
% surf(X,Y,Z) % filled in faces

Also check out

https://www.mathworks.com/matlabcentral/fileexchange/50105-icosphere

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Answer 2

Bruno Luong 2020-10-21

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https://ww2.mathworks.cn/matlabcentral/answers/618008-how-to-plot-sphere-in-sphere-coordinates#answer_520158

在 MATLAB Online 中打开

function sphere(r)
phi = linspace(0,2*pi);
theta = linspace(0,pi).'; % first change
x = r*cos(phi).*sin(theta);
y = r*sin(phi).*sin(theta);
z = r*cos(theta)+0*phi; % second change, make z same-size 2d array as x and y
plot3(x,y,z);
end