Some remarks of the Carath\'{e}odory's inequality on the right half plane
Commun. Korean Math. Soc. 2020 Vol. 35, No. 1, 201-215
https://doi.org/10.4134/CKMS.c180469
Published online January 31, 2020
B\"{u}lent Nafi \"{O}rnek
Amasya University
Abstract : In this paper, a boundary version of Carath\'{e}odory's inequality on the right half plane for $p$-valent is investigated. Let $Z(s)=1+c_{p}\left( s-1\right) ^{p}+c_{p+1}\left( s-1\right) ^{p+1}+\cdots$ be an analytic function in the right half plane with $\Re Z(s)\leq A$ $\left( A>1\right) $ for $\Re s\geq 0$ . We derive inequalities for the modulus of $Z(s)$ function, $|Z^{\prime }(0)|$, by assuming the $Z(s)$ function is also analytic at the boundary point $s=0$ on the imaginary axis and finally, the sharpness of these inequalities is proved.
Keywords : Schwarz lemma on the boundary, Carath\'{e}odory's inequality, analytic function
MSC numbers : Primary 30C80, 32A10
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