How to plot z = x^2 * y

x = linspace(-10, 10, 50);                                 
y = linspace(-10, 10, 50);                                 
[X,Y] = meshgrid(x,y); 
Z = X.^2. * Y;

figure(1)
surf(X, Y, Z)

Don't know why the output just shows a flat surface

Answer 1

[Voss]

You have an extra space between "." and "*"

Z = X.^2. * Y;
%        ^ space breaks up the .* operator

That causes Z to be the matrix product (*) of X.^2. and Y, which happens to result in a matrix containing one unique value very close to 0:

x = linspace(-10, 10, 50);                                 
y = linspace(-10, 10, 50);                                 
[X,Y] = meshgrid(x,y);

Z = X.^2. * Y;
unique(Z)

ans = -5.6843e-13

Remove the extra space, and you'll get Z to be the element-wise product (.*) of X.^2 and Y, as intended:

Z = X.^2.* Y;
surf(X, Y, Z)