Given an Arithmetic function, (or even better who's values are integers), how can I tell if it has an Analytic continuation to the whole plane, or maybe half plane?
I guess it might be too general a question.
-
$\begingroup$ this is not what you are asking for but you may look into en.wikipedia.org/wiki/Nevanlinna%E2%80%93Pick_interpolation $\endgroup$– KoushikDec 9, 2013 at 6:38
1 Answer
There are many such analytic continuations (though almost surely none of them interesting). You can always find an entire function taking whatever sequence of values you want. More precisely, given a sequence $\{z_1,z_2,\dots,\}$ of distinct complex numbers such that $|z_j|\to\infty$, and a second sequence $\{w_1,w_2,\dots\}$ of complex numbers, there exist uncountably many entire functions $f$ such that $f(z_j)=w_j$ for each $j$. So for example, there exist uncountably many entire functions $f$ such that $f(n)=\phi(n)$ for each positive integer $n$.
-
2$\begingroup$ I see, it's existence is an application of one theorem in Complex analysis. It's sad, since I hope to check the property of the function by considering it's Analytic continuation. One further question, how can I give a Analytic continuation explicitly? Or some interesting Analytic continuation. $\endgroup$ Dec 9, 2013 at 6:45
-
1