SOME RESULTS ON THE HYPER-ORDER OF SOLUTIONS OF HOMOGENE-OUS LINEAR DIFFERENTIAL EQUATIONS WITH MEROMORPHIC COEFFICIENTS

  • MANSOURIA SAIDANI
    Department of Mathematics, Laboratory of Pure and Applied Mathematics, University of Mostaganem (UMAB), B. P. 227 Mostaganem, ALGERIA
    saidaniman@yahoo.fr
  • BENHARRAT BELA¨IDI
    Department of Mathematics, Laboratory of Pure and Applied Mathematics, University of Mostaganem (UMAB), B. P. 227 Mostaganem, ALGERIA.
    benharrat.belaidi@univ-mosta.dz

Abstract

The purpose of this paper is the study of the growth of solutions of higher order linear differential equations f(k) + (Dk−1 + Bk−1eQk−1(z))f(k−1) + · · · + (D1 + B1eQ1(z)) f′ + (D0 + A1eP1(z) + A2eP2(z)) f = 0, where Ai(z) (̸≡ 0) (i = 1, 2), Bj(z) (̸≡ 0) (j = 1, ..., k − 1), Dm (z) (m = 0, ..., k−1) are meromorphic functions of finite order less than n, Pi (z) = ai,nzn+· · ·+ai,0 and Qj (z) = bj,nzn+· · ·+bj,0 are polynomials with degree n ≥ 1 such that ai,q, bj,q (i = 1, 2; j = 1, ..., k −1; q = 0, 1, ..., n) are complex numbers. Our results extend the previous results due to Habib and Bela¨ıdi [3], [11], [12] and Beddani and Hamani [4].

Cuvinte cheie

order of growth hyper-order exponent of convergence of zero sequence differential equation meromorphic function