I am trying to make a 3D plot of the function j, that has an input of u1, u2. I would like to plot the function such that I do not need to make an assignment to either u1 or u2. I have tried to make u1, u2, vectors and then plot the function using the surf function. However, I have been unsccessful so far. If anyone can help me, it will be greatly appreciated, thank you.
clc, clear, close all
[u1,u2] = meshgrid(-2:.2:2);
syms u1 u2
j = @(u1,u2) (u1^2+3*u1-4)*(u2^2-u2+6);