Generalized logarithmic derivative estimates of Gol'dberg-Grinshtein type

被引:23
作者
Heittokangas, J
Korhonen, R
Rättyä, J
机构
[1] Univ Joensuu, Dept Math, FIN-80101 Joensuu, Finland
[2] Univ Illinois, Dept Math, Urbana, IL 61801 USA
[3] Loughborough Univ Technol, Dept Math Sci, Loughborough LE11 3TU, Leics, England
关键词
D O I
10.1112/S0024609303002649
中图分类号
O1 [数学];
学科分类号
0701 ; 070101 ;
摘要
For f meromorphic in the complex plane and W meromorphic in the unit disc, sharp upper bounds are obtained for m (r, f((k))/f((j))) = 1/2pi integral(0)(2pi) log(+) \f((k))(re(itheta))/f((j))(re(itheta))\ dtheta, r < infinity and m (r, phi((k))/phi((j))) = 1/2pi integral(0)(2pi) log(+) \phi((k))(re(itheta))/phi((j))(re(itheta))\ dtheta, r < 1 where k and j are integers satisfying k > j greater than or equal to 0. The results generalize the logarithmic derivative estimate due to Gol'dberg and Grinshtein to derivatives of higher order.
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页码:105 / 114
页数:10
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