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Register a new userA Novel Subclass of Univalent Functions Involving Operators of Fractional Calculus
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In this paper, we introduce and investigate a novel class of analytic and univalent functions of negative coefficients in the open unit disk. For this function class, we obtain characterization and distortion theorems as well as the radii of close-to-convexity, starlikeness and convexity by using fractional calculus techniques.
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In this paper, by making use of a certain family of fractional derivative operators in the complex domain, we introduce and investigate a new subclass $mathcal{P}_{tau,mu}(k,delta,gamma)$ of analytic and univalent functions in the open unit disk $mathbb{U}$. In particular, for functions in the class $mathcal{P}_{tau,mu}(k,delta,gamma)$, we derive sufficient coefficient inequalities, distortion theorems involving the above-mentioned fractional derivative operators, and the radii of starlikeness and convexity. In addition, some applications of functions in the class $mathcal{P}_{tau,mu}(k,delta,gamma)$ are also pointed out.
We consider an integral transform introduced by Prabhakar, involving generalised multi-parameter Mittag-Leffler functions, which can be used to introduce and investigate several different models of fractional calculus. We derive a new series expression for this transform, in terms of classical Riemann-Liouville fractional integrals, and use it to obtain or verify series formulae in various specific cases corresponding to different fractional-calculus models. We demonstrate the power of our result by applying the series formula to derive analogues of the product and chain rules in more general fractional contexts. We also discuss how the Prabhakar model can be used to explore the idea of fractional iteration in connection with semigroup properties.
Let $mathcal{S}$ denote the family of all functions that are analytic and univalent in the unit disk $mathbb{D}:={z: |z|<1}$ and satisfy $f(0)=f^{prime}(0)-1=0$. In the present paper, we consider certain subclasses of univalent functions associated with the exponential function, and obtain the sharp upper bounds on the initial coefficients and the difference of initial successive coefficients for functions belonging to these classes.
Let $es$ be the class of analytic and univalent functions in the unit disk $|z|<1$, that have a series of the form $f(z)=z+ sum_{n=2}^{infty}a_nz^n$. Let $F$ be the inverse of the function $fines$ with the series expansion %in a disk of radius at least $1/4$ $F(w)=f^{-1}(w)=w+ sum_{n=2}^{infty}A_nw^n$ for $|w|<1/4$. The logarithmic inverse coefficients $Gamma_n$ of $F$ are defined by the formula $logleft(F(w)/wright),=,2sum_{n=1}^{infty}Gamma_n(F)w^n$. % In this paper, we determine the logarithmic inverse coefficients bound of $F$ for the class In this paper, we first determine the sharp bound for the absolute value of $Gamma_n(F)$ when $f$ belongs to $es$ and for all $n geq 1$. This result motivates us to carry forward similar problems for some of its important geometric subclasses. In some cases, we have managed to solve this question completely but in some other cases it is difficult to handle for $ngeq 4$. For example, in the case of convex functions $f$, we show that the logarithmic inverse coefficients $Gamma_n(F)$ of $F$ satisfy the inequality [ |Gamma_n(F)|,le , frac{1}{2n} mbox{ for } ngeq 1,2,3 ] and the estimates are sharp for the function $l(z)=z/(1-z)$. Although this cannot be true for $nge 10$, it is not clear whether this inequality could still be true for $4leq nleq 9$.
Inspired by the recent works of Srivastava et al. (HMS-AKM-PG), Frasin and Aouf (BAF-MKA) and others (Ali-Ravi-Ma-Mina-class,Caglar-Orhan,Goyal-Goswami,Xu-HMS-AML,Xu-HMS-AMC), we propose to investigate the coefficient estimates for a general class of analytic and bi-univalent functions. Also, we obtain estimates on the coefficients |a2| and |a3| for functions in this new class. Some interesting remarks, corollaries and applications of the results presented here are also discussed.
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