Saddle shaped 3D Plot?

Hi there. I'm trying to determine if this equation does indeed make a "saddle" shapped 3D plot in MATLAB.

Somehow, my code below says that the way the variables are inputted are invalid. Can anyone help?

clc
clear all

x = input('Give me the first number: ');
y = input('Give me the second number: ');

[Xm, Ym] = meshgrid(x,y)
Lm = x^2 - y^2

hdl = surf(Xm, Ym, Lm)

Answer 1

[Sammit Jain]

Here, try something like this:

x = 1:10;
y = -10:10;
[Xm, Ym] = meshgrid(x,y);
Lm = Xm.^2 - Ym.^2;
hdl = surf(Xm, Ym, Lm);

Now, let's get to why you were getting errors: 1. When you create meshgrids, you want to define an entire grid, so you need a range of values for both coordinates. 2. The variables you will use to calculate the z values (dependent on x and y) needs to use the mesh variables, and not the ones you defined earlier. 3. Remember to use element-wise operations in your Lm definition, as you want to collectively apply the operation to all elements (square in this case)

Note: Try out different values of x and y to see what you get. I got desirable results with these values.

Hope this helps. Cheers.

[Phuc Nguyen]

hi may i ask what if i want the program to ask the user to input the range of the values for both coordinates.

I wrote one but the program returned error.