Time for action - making a surface plot

1. 1. First we define the domain:

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

1. 2. Then we generate the mesh grids:

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

1. 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;

1. 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 is a matrix. Also, notice that surface uses the mesh grids and the resulting Z matrix as inputs.

You can, of course, change the different properties—just like we did for two-dimensional plotting. For example:

octave:106> surface(X,Y,Z, "linwidth", 4)
octave:107> set(gca, "linewidth", 2, "fontsize", 20, "xlim", [-2 2])
octave...