On the growth of entire and meromorphic functions of infinite order
Let \(\phi\) (x) be a positive increasing function satisfying \(\int^{\infty}dx/\phi (x)<\infty\). It is shown that if f is a meromorphic function, then there exists a set E of logarithmic density 1 such that \[ \lim_{r\to \infty,r\in E}\frac{\log M(r)}{T(r)\phi (\log T(r))\log (\phi (\log T(r)))}=0. \] Here M(r) and T(r) denote the maximum modulus and Nevanlinna characteristic of f. If f is entire, then \[ \lim_{r\to \infty,r\in E}\frac{\log M(r)}{T(r)\phi (\log T(r))}=0. \] The proof depends on the Poisson-Jensen formula, a growth lemma for real functions, and - in the case that f is meromorphic - Cartan's lemma. Next it is shown that the condition that \(\int^{\infty}dx/\phi (x)<\infty\) cannot be weakened. To construct examples which show this, the authors first use conformal mappings of strips to construct a function which is harmonic in the plane except on certain curves where it is subharmonic or superharmonic. Then they approximate this function by log\(| f|\) where f is meromorphic and has zeros (respectively poles) on these curves. The estimation of the asymptotic behavior of the conformal mapping of the strip seems to require some regularity hypothesis on \(\phi\) (x) which is not stated in the paper, but will be given in a forthcoming correction (same journal, to appear).
scientific article; zbMATH DE number 4190097
scientific article