On the Nevanlinna characteristic of f(z+η) and difference equations in the complex plane

Abstract

We investigate the growth of the Nevanlinna Characteristic of f(z+η) for a fixed ηin this paper. In particular, we obtain a precise asymptotic relation between T(r,f(z+η) and T(r,f), which is only true for finite order meromorphic functions. We have also obtained the proximity function and pointwise estimates of f(z+η)/f(z) which is a version of discrete analogue of the logarithmic derivative of f(z). We apply these results to give growth estimates of meromorphic solutions to higher order linear difference equations. This also solves an old problem of Whittaker concerning a first order difference equation. We show by giving a number of examples that all these results are best possible in certain senses. Finally, we give a direct proof of a result by Ablowitz, Halburd and Herbst.