Surface plot generation for a 3-variable function

Greetings, Could you please advise how to generate a surface plot for a 3- variable function. (The meshgrid and function are working properly but the surf() function keeps throwing out error and no graph appears)

u=1000:4:3000;

v=400:1.6:1200;

w=0.25:0.001:0.75;

[x,y,z]=meshgrid(u,v,w);

g=x*x+y*y-z*z;

surf(u,v,g)

Thanks!

Also Could you let me know how to plot surf(u,w,g) and surf (v,w,g) in separate graphs.

Answer 1

[Walter Roberson]

surf can only be used for rectangular (2d) data arrays.

For 3d data arrays your choices include

• isosurface
• slice
• volumeviewer or underlying functionality can be called directly in very recent releases
• vol3d v2 from File Exchange
• scatter3 and encode the value by color or size

Answer 2

[VBBV]

Try to use a for loop to plot the resulting expression in 3rd dimension as shown below since surf function plots 2D matrices only

u=100:5:300;
v=40:1.6:120;
w=0.25:0.1:0.75;
[x,y,z]=meshgrid(u,v,w);
g=x.^2+y.^2-z.^2;
hold on
for k = 1:length(size(z,3))
 surf(u,v,g(:,:,k))
end
colorbar
shading interp
view(3)
grid