GNU Octave

Time for action – making a surface plot

1. First we define the domain:

   octave:102> x = [-2:0.1:2]; y = x;
   

2. Then we generate the mesh grids:

   octave:103> [X Y] = meshgrid(x,y);
   

3. We can now calculate the range of f for all combinations of x and y values in accordance with Equation (3.4):

   octave:104> Z = X.^2 – Y.^2;
   

4. To make a surface plot of the graph we use:

   octave:105> surface(X,Y, Z)
   

   The result is shown below:

   

What just happened?

In Command 103, X is simply a matrix, where the rows are copies of x, and Y is a matrix where the columns are copies of the elements in y. From X and Y, we can then calculate the range as done in Command 104. We see that Z