四维曲面如何画？matlab

clc;
clear all
[theta,phi]=meshgrid(linspace(0,pi,50),linspace(0,2*pi,50));

z=cos(theta);

x=sin(theta).*cos(phi);

y=sin(theta).*sin(phi);

f=-1*((x.*y).^2+(y.*z).2+(z.*x).^2);

surf(sin(theta).*cos(phi).*f,sin(theta).*sin(phi).*f,cos(theta).*f,f)

结果