English

Criteria for univalence, Integral means and Dirichlet integral for Meromorphic functions

Complex Variables 2017-05-11 v1

Abstract

Let A(p)\mathcal{A}(p) be the class consisting of functions ff that are holomorphic in \ID{p}\ID\setminus \{p\}, p(0,1)p\in (0,1) possessing a simple pole at the point z=pz=p with nonzero residue and normalized by the condition f(0)=0=f(0)1f(0)=0=f'(0)-1. In this article, we first prove a sufficient condition for univalency for functions in A(p)\mathcal{A}(p). Thereafter, we consider the class denoted by Σ(p)\Sigma(p) that consists of functions fA(p)f \in \mathcal{A}(p) that are univalent in \ID\ID. We obtain the exact value for \dsmaxfΣ(p)Δ(r,z/f)\ds\max_ {f\in \Sigma(p)}\Delta(r,z/f), where the Dirichlet integral Δ(r,z/f)\Delta(r,z/f) is given by Δ(r,z/f)=\dsz<r(z/f(z))2dxdy,(z=x+iy), 0<r1. \Delta(r,z/f)=\ds\iint_{|z|<r} |\left(z/f(z)\right)'|^2 \,dx\, dy, \quad(z=x+iy),~0<r\leq 1. We also obtain a sharp estimate for Δ(r,z/f)\Delta(r,z/f) whenever ff belongs to certain subclasses of Σ(p)\Sigma(p). Furthermore, we obtain sharp estimates of the integral means for the aforementioned classes of functions.

Keywords

Cite

@article{arxiv.1705.03663,
  title  = {Criteria for univalence, Integral means and Dirichlet integral for Meromorphic functions},
  author = {Bappaditya Bhowmik and Firdoshi Parveen},
  journal= {arXiv preprint arXiv:1705.03663},
  year   = {2017}
}

Comments

11 pages, Bulletin of the Belgian Math. Soc. Simon Stevin, To appear