International Refereed Journal of Engineering and Science (IRJES) ISSN (Online) 2319-183X, (Print) 2319-1821 Volume 2, Issue 5(May 2013), PP.08-15 www.irjes.com
On A Class Of đ?’‘ −Valent Functions Involving Generalized Hypergeometric Function Chena Ram And Saroj Solanki Department of Mathematics and Statistics, Jai Narain Vyas University Jodhpur, (Rajasthan), India.
Abstract: Invoking the Hadamard product (or convolution), a class of p-valent functions has been introduced. The coefficient bounds, extreme points, radii of close-to-convex, starlikeness and convexity are obtained for the same class of functions. Distortion theorem and fractional differ-integral operators are also obtained. Key words: đ?‘?-valent function; Analytic function; Hadamard product; Generalized hyper-geometric functions; Linear operator; Starlike function; Convex function; Fractional differential and integral operator.
I. Introduction Let đ??´(đ?‘›, đ?‘?) denote the class of functions đ?‘“(đ?‘§) of the form ∞
đ?‘“ đ?‘§ = đ?‘§đ?‘? +
đ?‘Žđ?‘› +đ?‘? đ?‘§ đ?‘›+đ?‘? , đ?‘?, đ?‘› ∈ N = 1,2, ‌ ‌ ,
(1.1)
đ?‘› =1
which are analytic and đ?&#x2018;? â&#x2C6;&#x2019;valent in the unit disk đ?&#x2022;&#x152; = { đ?&#x2018;§ â&#x2C6;ś đ?&#x2018;§ < 1}. A function đ?&#x2018;&#x201C;(đ?&#x2018;§) â&#x2C6;&#x2C6; đ??´ (đ?&#x2018;&#x203A;, đ?&#x2018;?) is said to be đ?&#x2018;? â&#x2C6;&#x2019;valent starlike of order đ?&#x203A;ż (0 â&#x2030;¤ đ?&#x203A;ż < đ?&#x2018;?) if and only if Re
đ?&#x2018;§đ?&#x2018;&#x201C; â&#x20AC;˛ (đ?&#x2018;§)
> đ?&#x203A;ż , đ?&#x2018;§ â&#x2C6;&#x2C6; đ?&#x2022;&#x152;; 0 â&#x2030;¤ đ?&#x203A;ż < đ?&#x2018;? .
đ?&#x2018;&#x201C;(đ?&#x2018;§ )
(1.2)
We denote by đ?&#x2018;&#x2020;đ?&#x2018;&#x203A; đ?&#x2018;?, đ?&#x203A;ż the subclass of đ??´(đ?&#x2018;&#x203A;, đ?&#x2018;?) consisting of functions which are đ?&#x2018;? â&#x2C6;&#x2019;valent starlike of order đ?&#x203A;ż. Also a function đ?&#x2018;&#x201C; đ?&#x2018;§ â&#x2C6;&#x2C6; đ??´(đ?&#x2018;&#x203A;, đ?&#x2018;?) is said to be in the class đ??žđ?&#x2018;&#x203A; đ?&#x2018;?, đ?&#x203A;ż if and only if Re 1 +
đ?&#x2018;§đ?&#x2018;&#x201C; â&#x20AC;˛â&#x20AC;˛ (đ?&#x2018;§) đ?&#x2018;&#x201C; â&#x20AC;˛(đ?&#x2018;§ )
> đ?&#x203A;ż , (đ?&#x2018;§ â&#x2C6;&#x2C6; đ?&#x2022;&#x152;; 0 â&#x2030;¤ đ?&#x203A;ż < đ?&#x2018;?).
(1.3)
A function đ?&#x2018;&#x201C; đ?&#x2018;§ â&#x2C6;&#x2C6; đ??žđ?&#x2018;&#x203A; đ?&#x2018;?, đ?&#x203A;ż is called đ?&#x2018;? -valent convex function of order đ?&#x203A;ż (0â&#x2030;¤ đ?&#x203A;ż < đ?&#x2018;?), if đ?&#x2018;&#x201C; đ?&#x2018;§ â&#x2C6;&#x2C6; đ??žđ?&#x2018;&#x203A; đ?&#x2018;?, đ?&#x203A;ż ď&#x192;ł đ?&#x2018;§đ?&#x2018;&#x201C; â&#x20AC;˛ (đ?&#x2018;§) â&#x2C6;&#x2C6; đ?&#x2018;&#x2020;đ?&#x2018;&#x203A; đ?&#x2018;?, đ?&#x203A;ż , â&#x2C6;&#x20AC; đ?&#x2018;&#x203A; â&#x2C6;&#x2C6; đ?&#x2018; . For a function đ?&#x2018;&#x201C;(đ?&#x2018;§) is given by (1.1) and đ?&#x2018;&#x201D;(đ?&#x2018;§) â&#x2C6;&#x2C6; đ??´ đ?&#x2018;&#x203A;, đ?&#x2018;? is given by
(1.4)
â&#x2C6;&#x17E;
đ?&#x2018;?
đ?&#x2018;?đ?&#x2018;&#x203A;+đ?&#x2018;? đ?&#x2018;§ đ?&#x2018;&#x203A;+đ?&#x2018;? ,
đ?&#x2018;&#x201D; đ?&#x2018;§ =đ?&#x2018;§ +
đ?&#x2018;? ,đ?&#x2018;&#x203A; â&#x2C6;&#x2C6; N ,
(1.5)
đ?&#x2018;&#x203A; =1
we define the Hadamard product of đ?&#x2018;&#x201C; đ?&#x2018;§ and đ?&#x2018;&#x201D; đ?&#x2018;§ as â&#x2C6;&#x17E;
đ?&#x2018;?
đ?&#x2018;&#x17D;đ?&#x2018;&#x203A; +đ?&#x2018;? đ?&#x2018;?đ?&#x2018;&#x203A;+đ?&#x2018;? đ?&#x2018;§ đ?&#x2018;&#x203A;+đ?&#x2018;? ,
đ?&#x2018;&#x201C;â&#x2C6;&#x2014;đ?&#x2018;&#x201D; đ?&#x2018;§ = đ?&#x2018;§ +
đ?&#x2018;§ â&#x2C6;&#x2C6; đ?&#x2022;&#x152;.
(1.6)
đ?&#x2018;&#x203A;=1
Let the subclass A đ?&#x2018;&#x203A;, đ?&#x2018;? is denoted by đ?&#x153;&#x2018; consisting of functions of the form â&#x2C6;&#x17E;
đ?&#x2018;?
đ?&#x2018;&#x17D;đ?&#x2018;&#x203A; +đ?&#x2018;? đ?&#x2018;§ đ?&#x2018;&#x203A; +đ?&#x2018;? ,
đ?&#x2018;&#x201C; đ?&#x2018;§ =đ?&#x2018;§ â&#x2C6;&#x2019;
đ?&#x2018;? , đ?&#x2018;&#x203A; â&#x2C6;&#x2C6; N; đ?&#x2018;&#x17D;đ?&#x2018;&#x203A; â&#x2030;Ľ 0 .
(1.7)
đ?&#x2018;&#x203A;=1
Invoking the Hadamard product, a linear operator đ??żđ?&#x2018;&#x2DC;đ?&#x2018;? đ?&#x2018;&#x17D;, đ?&#x2018;?, đ?&#x2018;? đ?&#x2018;&#x201C;(đ?&#x2018;§) is defined as đ??żđ?&#x2018;&#x2DC;đ?&#x2018;? đ?&#x2018;&#x17D;, đ?&#x2018;?, đ?&#x2018;? đ?&#x2018;&#x201C; đ?&#x2018;§ = (đ?&#x2018;§ đ?&#x2018;? 2đ?&#x2018;&#x2026;1 đ?&#x2018;&#x17D;, đ?&#x2018;?; đ?&#x2018;?; đ?&#x2018;&#x2DC;; đ?&#x2018;§ ) â&#x2C6;&#x2014; đ?&#x2018;&#x201C; đ?&#x2018;§ â&#x2C6;&#x17E; Î&#x201C; đ?&#x2018;? (đ?&#x2018;&#x17D;)đ?&#x2018;&#x203A; Î&#x201C; đ?&#x2018;? + đ?&#x2018;&#x2DC;đ?&#x2018;&#x203A; đ?&#x2018;&#x17D;đ?&#x2018;&#x203A;+đ?&#x2018;? đ?&#x2018;§ đ?&#x2018;&#x203A;+đ?&#x2018;? đ?&#x2018;? =đ?&#x2018;§ â&#x2C6;&#x2019; Î&#x201C;đ?&#x2018;? Î&#x201C; đ?&#x2018;? + đ?&#x2018;&#x2DC;đ?&#x2018;&#x203A; đ?&#x2018;&#x203A; ! â&#x2C6;&#x17E; đ?&#x2018;?
đ?&#x2018;&#x17D;đ?&#x2018;&#x203A;+đ?&#x2018;? đ??ľ đ?&#x2018;&#x203A; đ?&#x2018;§ đ?&#x2018;&#x203A; +đ?&#x2018;? ,
=đ?&#x2018;§ â&#x2C6;&#x2019;
(1.8)
đ?&#x2018;&#x203A;=1
(1.9)
đ?&#x2018;&#x203A; =1
where 2đ?&#x2018;&#x2026;1 đ?&#x2018;&#x17D;, đ?&#x2018;?; đ?&#x2018;?; đ?&#x2018;§ is generalized hypergeomertric function defined by Virchenko, Kalla and Al-Zamel [6] as, â&#x2C6;&#x17E; Î&#x201C;đ?&#x2018;? (đ?&#x2018;&#x17D;)đ?&#x2018;&#x203A; Î&#x201C; đ?&#x2018;? + đ?&#x2018;&#x2DC;đ?&#x2018;&#x203A; đ?&#x2018;§ đ?&#x2018;&#x203A; , đ?&#x2018;&#x2DC; â&#x2C6;&#x2C6; đ?&#x2018;&#x2026;, đ?&#x2018;&#x2DC; > 0, đ?&#x2018;§ < 1, (1.10) 2 đ?&#x2018;&#x2026;1 đ?&#x2018;&#x17D;, đ?&#x2018;?; đ?&#x2018;?; đ?&#x2018;&#x2DC;; đ?&#x2018;§ = Î&#x201C;đ?&#x2018;? Î&#x201C; đ?&#x2018;? + đ?&#x2018;&#x2DC;đ?&#x2018;&#x203A; đ?&#x2018;&#x203A; ! đ?&#x2018;&#x203A;=0
where (đ?&#x2018;&#x17D;)đ?&#x2018;&#x203A; is the pochhammer symbol defined as
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