1. The problem statement, all variables and given/known data For example: the function is A0sin(w0*t - B*z) If I take the partial derivative with respect to z, how do you go about this? In my years at uni, I don't know if this has ever come up. 2. Relevant equations 3. The attempt at a solution My initial thoughts are that it is either 0, or to use the chain rule, although I'm having trouble thinking of how I would do that in this case. Any help is greatly appreciated, thanks!