I wondering if there is a mathematician here that can help me. I need help setting up an XP curve that looks like a Sigmoid Function. I've found the equation for it and even videos about it but what I really need to know is how to take the derivative at any given point. I know what these words mean, but I haven't a clue as to how they actually work i.e. I don't know how to take a derivative. So if someone could walk me through the process I'd really appreciate the help!