Conversely, every holomorphic function on the upper half-plane which is uniformly square-integrable on every horizontal line will arise in this manner.
Furthermore, holomorphy is a necessary condition for a function to have an antiderivative, since the derivative of any holomorphic function is holomorphic.
This zeta-function universality states that there exists some location on the critical strip that approximates any holomorphic function arbitrarily well.
