Browsing by Author "Owa, Shigeyoshi"
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Generalized Hankel determinant for a general subclass of univalent functions
Yalçın, Sibel; Altınkaya, Şahsene; Owa, Shigeyoshi (Işık University Press, 2018)Making use of the generalized Hankel determinant, in this work, we consider a general subclass of univalent functions. Moreover, upper bounds are obtained for a3 − µa2 2, where µ ∈ R. 
New sufficient conditions for starlike and convex functions
Nishiwaki, Junichi; Owa, Shigeyoshi (Işık University Press, 2014)Let A be the class of analytic functions f(z) in the open unit disc. Applying the subordination, some sufficient conditions for starlikeness and convexity are discussed. 
Notes on certain harmonic starlike mappings
Yavuz Duman, Emel; Owa, Shigeyoshi (Işık University Press, 2014)Complexvalued harmonic functions that are univalent and sensepreserving in the unit disk D can be written in the form f = h + ¯g, where h and g are analytic in D. We give some inequalities for normalized harmonic functions ... 
Notes on starlike logharmonic functions of order α
For logharmonic functions f(z) = zh(z)g(z) in the open unit disk U, two subclasses H*LH(?) and G*LH(?) of S*LH(?) consisting of all starlike logharmonic functions of order ? (0 ? ? < 1) are considered. The object of ... 
Some properties concerning closetoconvexity of certain analytic functions
Nunokawa, Mamoru; Aydoğan, Seher Melike; Kuroki, Kazuo; Yıldız, İsmet; Owa, Shigeyoshi (Springer International Publishing AG, 2012)Let f(z) be an analytic function in the open unit disk D normalized with f(0) = 0 and f'(0) = 1. With the help of subordinations, for convex functions f(z) in D, the order of closetoconvexity for f(z) is discussed with ... 
Some results on a subclass of harmonic mappings of order alpha
Varol, Dürdane; Aydoğan, Seher Melike; Owa, Shigeyoshi (Işık University Press, 2014)Let SH be the class of harmonic mappings defined by SH = { f = h(z) + g(z) h(z) = z + ∑∞ n=2 anzⁿ, g(z) = b1z + ∑∞ n=2 bnzⁿ, b1 < 1 } where h(z) and g(z) are analytic. Additionally f(z) ∈ SH(α) ⇔  zh′ (z) − zg′(z) h(z) ...