clear all; close all;

x=linspace(-3,3,50);
y=x; z=x;

[X,Y,Z]=meshgrid(x,y,z);

u=cos(X).*cos(Y).*cos(Z);

isosurface(x,y,z,u,0.5), grid on
alpha(0.8), hold on
isosurface(x,y,z,u,-0.5)
isosurface(x,y,z,u,0.25)
isosurface(x,y,z,u,-0.25)

figure(2)
slice(x,y,z,u,[0 3],3,[0 -3])
colormap(hot)
shading interp

figure(3)
isosurface(x,y,z,u,0.5), grid on
alpha(0.8), hold on
isosurface(x,y,z,u,-0.5)
isosurface(x,y,z,u,0.25)
isosurface(x,y,z,u,-0.25)
slice(x,y,z,u,3,3,-3)
%colormap(hot)
%shading interp