As it happens you don't need to, at the command prompt now type:

If you want them on the same plot you will needCode:>>plot(x,(f(x+0.1)-f(x))/0.1,'r') >>plot(x,(f(x+0.01)-f(x))/0.01,'g') >>plot(x,(f(x+0.001)-f(x))/0.001,'b') >>plot(x,(f(x+0.0001)-f(x))/0.0001,'m')

before hand, (and sort out axes)Code:>>hold on

CB