Question: How can I plot the derivative of a function? Following code for problem 5.9 in MatLab by Gilat 4th Ed: t=[0:1:20]; theta=pi*(1-exp(-0.2*t)); r=20+30*(1-exp(-0.1*t)); v=diff(theta) table=[t' theta' r'] polar(theta,r) polar(theta,v) Error message: ??? Error using ==> polar at 61 THETA and RHO must be the same size. Error in ==> Prob5_16 at 12 polar(theta,v) I have looked around for what may be the larger issue and it seems that when you use the "diff" function it shortens one dimension of the array (https://www.physicsforums.com/showthread.php?t=55524) Any help please? The link provides "an answer" but i don't understand what he means.