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JOURNALS // Matematicheskie Zametki // Archive

Mat. Zametki, 1976 Volume 19, Issue 4, Pages 525–530 (Mi mzm7770)

This article is cited in 4 papers

The logarithmic derivative of a meromorphic function

A. A. Gol'dberg, V. A. Grinshtein

L'vov State University

Abstract: A well-known lemma on the logarithmic derivative for a function $f(z)$, $f(0)=1$ ($0<r<\rho<R$), meromorphic in $\{|z|<R\le\infty\}$ is proved in the following form:
$$ m\Bigl(r,\frac{f'}f\Bigr)<ln+\Bigl\{\frac{T(\rho,f)}r\frac\rho{\rho-r}\Bigr\}+5,\!8501. $$

This estimate is more exact than the one previously obtained by Kolokol'nikov and is, in a certain sense, unimprovable.

UDC: 517.5

Received: 09.04.1975


 English version:
Mathematical Notes, 1976, 19:4, 320–323

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