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Sharp norm estimate of Schwarzian derivative for a class of convex functions

100%

Kanas S., Sugawa T.

Annales Polonici Mathematici

2011

tom 101

nr 1

75-86

We establish a sharp norm estimate of the Schwarzian derivative for a function in the classes of convex functions introduced by Ma and Minda [Proceedings of the Conference on Complex Analysis, Int. Press, 1992, 157-169]. As applications, we give sharp norm estimates for strongly convex functions of order α, 0 < α < 1, and for uniformly convex functions.

Variability regions of close-to-convex functions

81%

Kato T., Sugawa T., Wang L.-M.

Annales Polonici Mathematici

2014

tom 111

nr 1

89-105

M. Biernacki gave in 1936 concrete forms of the variability regions of z/f(z) and zf'(z)/f(z) of close-to-convex functions f for a fixed z with |z|<1. The forms are, however, not necessarily convenient to determine the shape of the full variability region of zf'(z)/f(z) over all close-to-convex functions f and all points z with |z|<1. We propose a couple of other forms of the variability regions and see that the full variability region of zf'(z)/f(z) is indeed the complex plane minus the origin. We also apply them to study the variability regions of log[z/f(z)] and log[zf'(z)/f(z)].

Ograniczanie wyników

2 Annales Polonici Mathematici

2 Sugawa T.

1 Kanas S.

1 Kato T.

1 Wang L.-M.

1 2014

1 2011

Wyniki wyszukiwania

Sharp norm estimate of Schwarzian derivative for a class of convex functions

Variability regions of close-to-convex functions