- #1

- 933

- 56

Suppose we have a function ##\vartheta'(\vartheta) = \vartheta## and that ##\vartheta = \vartheta(\varphi)## and we know what ##\vartheta(\varphi)## is. How should I view ##\frac{\partial \vartheta'}{\partial \varphi}##? Should I set it equal to zero because ##\varphi## does not appear explicitely? But as I said, I

*know*what ##\vartheta(\varphi)## is in this particular case, and it is not even linear in ##\varphi##, so it doesn't make sense to say that its derivatives vanish.

Edit: I added a crucial correction to my post.