Chapter 4: Programming in Matlab - College of the Redwoods

Section 4.1 Logical Arrays 283
That checks.
Next, create the rectangular grid and evaluate z at each point (x, y) in the
grid.
[x,y]=meshgrid(linspace(-1,1,50));
z=f(x,y);
Now, find those values of the grid that satisfy y < x and y > −x.
k=(y-x);
We want to eliminate from the mesh all points that do not satisfy this requirement.
z(~k)=NaN;
We can now draw the resulting mesh, label the axes, and provide an orientation.
mesh(x,y,z)
xlabel(’x-axis’)
ylabel(’y-axis’)
zlabel(’z-axis’)
box on
view(145,20)
The result is shown in Figure 4.5(a).
An interesting view is provided by the following command, the result of which
is shown in Figure 4.5(b). In this view, we’ve declined to rotate the xy-axes, but
elevated our eye 90 ◦ , so that we are gazing directly down at the xy-plane. This
view clearly shows that we have sketched the surface of a region in the rectangular
domain restricted to (x, y) pairs satisfying y < x and y > −x.
view(0,90)