I have a question about notation specifically square brackets $[$ and round brackets $($.
My textbook doesn't explain any of this and I cannot find a reliable source online to confirm the difference.
So my question is: What is the difference between round brackets and square brackets in terms of notation in Field Theory? For example, I see $F(x)$ and $F[x]$ in my textbook and I've always assumed they were the same thing. But apparently they're not. Is there ever a time they're the same?
I wanted to know the difference, it may be a silly question but it's something I want to make sure I understand.