Is there expression for an operator that gives for any analytic periodic function its period?
P.S.
In my view this probably means solving the following system of equations:
$$f^{(n)}(0)=f^{(n)}(T)$$
against $T$.
I just wonder whether the solution to this system can be written in a form of one expression.
P.P.S. Alternatively the equation can be written as
$$\Delta f(Tz)≡0$$