I'm not sure what you're aiming to do, but you could use the hold function to plot two or more graphs on the same graph, like this:
figure
hold on;
plot(x1, y1)
plot(x2, y2)
Or you could use a subplot to put two or more graphs separately on one window:
figure
subplot(m,n,p1) % m is num of rows, n is num of columns, p is the index
plot(x1,y1)
subplot(m,n,p2)
plot(x2,y2)
It depends on what you want your output to look like.
