I am a student currently studying Computational Models. I still don't have a full understanding of the subject and was wondering about languages of the form $L = \left \{(n,w) | f(n) = w \right \}$ which we didn't discuss in class.
For starters, consider the language:
L = {$(n,w)$ $|w$ is a binary representation of the n-th Fibonacci number}
And the decision problem: "is $(n,w) \in L$?"
Is this problem a member of $P$ - The class of decision problems which has a deterministic Turing machine that decides it in poynomial time?
I suspect this is correct since it has a closed formula, but am not sure of the capabilities of Turing machines in calculating this kind of functions.
Thanks