%an example of a 3D surface plot
x_space = [-2.5:0.1:2.5];
y_space = [-2.5:0.1:2.5];
[X, Y] = meshgrid(x_space, y_space);
%We get X, Y - the coordinate arrays for the mesh
% USE THOSE TO COMPUTE THE Z VALUES!
Z = 0.5*X.*Y;
mesh(X,Y,Z); %can use surf or mesh
axis equal;
axis([-3,3,-3,3,-7,7,-5, 5]);
%set up: x-axis: -3 to 3
%        y-axis: -3 to 3
%        z-axis: -9 to 9
%color axis: blue at -10, red at 10