Open Unit Disk Research Articles

Applications of (M,N)-Lucas Polynomials for a Certain Family of Bi-Univalent Functions Associating λ-Pseudo-Starlike Functions with Sakaguchi Type Functions

In this article, we use the (M,N)-Lucas Polynomials to determinate upper bounds for the Taylor-Maclaurin coefficients $\left|a_{2}\right|$ and $\left| a_{3}\right|$ for functions belongs to a certain family of holomorphic and bi-univalent functions associating $\lambda$-pseudo-starlike functions with Sakaguchi type functions defined in the open unit disk $\mathbb{D}$. Also, we discuss Fekete-Szeg\"{o} problem for functions belongs to this family.

Finite Sum of Integral Operators from the Fractional Cauchy Spaces to Bloch-Type and Zygmund-Type Spaces

The family of fractional Cauchy transforms, defined on the open unit disc in the complex plane, is of classical and modern interest. Membership of an analytic function in the family is determined by the requirement that the function can be expressed as an integral of a certain kernel against a complex Borel measure on the disc. Such an integral representation imposes a growth condition on the function and its derivatives. This exposes a connection between the families of Cauchy transforms and familiar spaces of analytic functions, such as the Bloch spaces and the Zygmund space. The notion of a composition operator has been a fruitful area of study. More generally, many authors have studied weighted composition operators, the differentiation operator, integral-type operators, and various products of such operators, acting from one normed linear space of analytic functions to another such space. A common theme of such works is to characterize the operator-theoretic notions of boundedness and compactness in terms of the inducing symbols of the operator. We extend these studies to a specific linear transformation which will be defined as the sum of finitely many integral operators. Our conclusions include a complete characterization of boundedness and compactness of the integral sum, acting from the fractional Cauchy spaces to the Bloch-type and Zygmund-type spaces.

Majoration of the modulus of the Schwarzian of certain quasi-conformal maps

In this work, we have proposed a majoration of the modulus of the Schwarzian of certain quasi-conformal maps, defined in the open unit disk ∆ = z ∈ C : |z| < 1}. Using the Schwarzian, we have found some relations linking the Taylor coefficients of these maps.

New Results on Differential Subordination and Superordination for Multivalent Functions Involving New Symmetric Operator

This article aims to significantly advance geometric function theory by providing a valuable contribution to analytic and multivalent functions. It focuses on differential subordination and superordination, which characterize the interactions between analytic functions. To achieve our goal, we employ a method that relies on the characteristics of differential subordination and superordination. As one of the latest advancements in this field, this technique is able to derive several results about differential subordination and superordination for multivalent functions defined by the new operator within the open unit disk . Additionally, by employing the technique, the differential sandwich outcome is achieved. Therefore, this work presents crucial exceptional instances that follow the results. The findings of this paper can be applied to a wide range of mathematical and engineering problems, including system identification, orthogonal polynomials, fluid dynamics, signal processing, antenna technology, and approximation theory. Furthermore, this work significantly advances the knowledge and understanding of the analytical functions of the unit and its interactive higher relations. The characteristics and consequences of differential subordination theory are symmetric to those of differential superordination theory. By combining them, sandwich-type theorems can be derived.

Invariant subspaces of analytic perturbations

Analytic perturbations are understood here as shifts of the form M z + F M_z + F , where M z M_z is the unilateral shift and F F is a finite rank operator on the Hardy space over the open unit disk. Here the term “a shift” refers to the multiplication operator M z M_z on some analytic reproducing kernel Hilbert space. In this paper, first, a natural class of finite rank operators is isolated for which the corresponding perturbations are analytic, and then a complete classification of invariant subspaces of those analytic perturbations is presented. Some instructive examples and several distinctive properties (like cyclicity, essential normality, hyponormality, etc.) of analytic perturbations are also described.

Properties and Applications of Complex Fractal–Fractional Operators in the Open Unit Disk

A fractal–fractional calculus is presented in term of a generalized gamma function (ℓ−gamma function: Γℓ(.)). The suggested operators are given in the symmetric complex domain (the open unit disk). A novel arrangement of the operators shows the normalization associated with every operator. We investigate a number of significant geometric features thanks to this. Additionally, some integrals, such the Alexander and Libra integral operators, are associated with these operators. Simple power functions are among the illustrations that are provided. Additionally, the formulation of the discrete ℓ−fractal–fractional operators is conducted. We demonstrate that well-known examples are involved in the extended operators.

Some Coefficient Problems for Subclasses of Holomorphic Functions in Complex Order Associating Sălăgeăn q-Differential Operator

A function with complex values and at every point of the specific domain contains a derivative is commonly known as analytic functions which is also referred as holomorphic functions. We begin by interpreting \(A\) as the class for all holomorphic functions \(L(\xi)\) with a Taylor series expansion written in the form: \[L(\xi) = \xi + \sum_{i=2}^{\infty} x_i \xi^i\] where \(x_i \in \mathbb{C}\) and \(\xi \in D\). \(D\) is the open unit disk where \(D = \{\xi : \xi \in \mathbb{C}, |\xi| < 1 \}\). Furthermore, we suggest the subclass of \(A\) that is univalent in \(D\) represented as \(S\). It is commonly known that the main subclasses of class \(S\) are the class of starlike functions and the class of convex functions. To develop and analyze the Fekete-Szegö problems, the theory of geometric function contributes significantly to this. Moreover, the frequent use of \(q\)-calculus as a general direction of research among mathematicians has caught our attention. In this research, we attained the initial coefficients, \(x_2\) and \(x_3\), and the upper bound for the functional \(|x_3 - \nu x_2^2|\) of functions \(L\) in the two new subclasses that are introduced by involving the Sălăgeăn \(q\)-differential operator, \(M_q^\eta L(\xi)\) and the definition of subordination.

Certain Subclass of Harmonic Multivalent Functions Defined by New Linear Operator

The main goal of the present paper is to introduce a new class of harmonic multivalent functions defined by a new linear operator in the open unit disc . Thus, some geometric properties have examined, including coefficient inequality, extreme points, convolution conditions, convex linear combinations, and integral transforms for the class .

Some Geometric Properties of Close- to- Convex Functions

The objective of this paper is to present some geometric properties of the close to convex function f when f is an analytic, univalent self-conformal mapping defined in the open unit disk D={z∈C: |z|<1}, and on the boundary of D. One of the goals of this work was determining the sharp bound for the function of form f(z)=z/(1-z)^2δ , 0<δ<1, when R(f^'/g^' (w_1))≥-2+δ/w_1 , for a some w_1∈∂D And another, if f has angular limit at p∈∂D . Then the inequality |(f^' (z))/(g^' (z) )|≥(-(1-2δ))/2(1+ δ) is sharp with extremal functions f(z)=z/(1-z)^2δ , and g(z)=z/(1+z), where 0<δ<1. Finally, if f is extended continuously to the boundary of D , then | (f^'/g^' )(p)|≥ |1-2δ|(|1-2δ|-2)/|p-δ | ; 0<δ<1.

Some Characteristics Properties for Linear Operator on Class of Multivalent Analytic Functions Defined by Differential Subordination

The purpose of this paper is to consider a linear operator and define a certain class of analytic and multivalent functions in the open unit disk associated with differential subordination. Also, we discuss some geometric properties for this class.

Certain theorems involving differential superordination and sandwich-type results

Abstract. To obtain the main result of the present paper, we use the technique of differential superordination. As special cases of our main result, we obtain sufficient conditions for f ∈ A to be φ−like, parabolic φ−like, starlike, parabolic starlike, close-to-convex and uniform close-to-convex. We also obtain sandwich-type results regarding these functions. For demonstration of the results, we have plotted the images of open unit disk under certain functions using Mathematica 7.0. Mathematics Subject Classification (2010): 30C80, 30C45. Keywords: Analytic function, differential superordination, φ−like function, starlike function, close-to-convex function.

On P-Stable Functions

Let h_1, h_2 be two analytic functions defined in the open unit disc Δ:={z∈C:|z|<1} which are normalized by the condition h_1 (0)=1=h_2 (0). Then h_1 is P-stable with respect to h_2, whenever (P_n (h_1,z))/(h_1 (z))≺1/(h_2 (z)) (z∈Δ),holds for all n∈N. Here ’≺’ stands for subordination and P_n (h,z)=P_n (z)*h(z) where P_n (z) denote the n-degree polynomial induced by the (n+1)th row entities in an admissible lower triangular matrix. The main purpose of this article is to prove that the function ((Az+1)/(Bz+1))^δ is P-stable with respect to (Bz+1)^(-δ), for δ∈(0,1] and -1≤B<A≤0 but not P-stable with respect to itself, when -1≤B<A<0 and δ∈(0,1]. As an application, considered different admissible lower triangular matrices to derive various results related on stability.

On the structure of the matrix in Sturm algorithm for determining the number of zeros in the open unit disk for a real polynomial

In 1984, C.W Schelin presented a numerical method for calculating the number of zeros of a real polynomial inside the unit disk using the argument principle and Cauchy index on [-1, 1] inspired by sturm’s algorithm [3], this method is based on calculation of the generalized Sturm sequence in Chebyshev form, however in some cases this algorithm does not efficient for this reason, it has been modified in another works [1], [2]. There are other numerical algorithms for calculating the number of zeros of a polynomial in the unit disk like shur -Cohn and Marden-Cohn but the numerical method presented in this study [1] is more efficient in cost of elementary operations (o (n2)). In this paper, we propose to improve this algorithm [1], to do this we study the matrix structure involved in the calculation of chebychev polynomials, for there on we prove that is a Toeplitz matrix which is known for their important properties in the complexity of calculations and we calculate its last line which is necessary to define the whole matrix to solve the linear system for calculating polynomials which are necessary to obtain Chebyshev sequence, this result will reduce calculation steps in this method [1]. This numerical algorithm may operate to study the stability of dynamical systems [2].

Applications of Generalized Hypergeometric Distribution on Comprehensive Families of Analytic Functions

A sequence of n trials from a finite population with no replacement is described by the hypergeometric distribution as the number of successes. Calculating the likelihood that factory-produced items would be defective is one of the most popular uses of the hypergeometric distribution in industrial quality control. Very recently, several researchers have applied this distribution on certain families of analytic functions. In this study, we provide certain adequate criteria for the generalized hypergeometric distribution series to be in two families of analytic functions defined in the open unit disk. Furthermore, we consider an integral operator for the hypergeometric distribution. Some corollaries will be implied from our main results.

Exploration of Multivalent Harmonic Functions: Investigating Essential Properties

Within this manuscript, we introduce an innovative subclass of multivalent harmonic functions, encompassing higher-order derivatives within the confines of an open unit disk. Our investigation extends to the analysis of coefficient bounds, growth estimates, starlikeness, and convexity radii uniquely associated with this particular class. Furthermore, we scrutinize the property of closure under convolution operations for this subclass.

Applications of Caputo-Type Fractional Derivatives for Subclasses of Bi-Univalent Functions with Bounded Boundary Rotation

In this article, for the first time by using Caputo-type fractional derivatives, we introduce three new subclasses of bi-univalent functions associated with bounded boundary rotation in an open unit disk to obtain non-sharp estimates of the first two Taylor–Maclaurin coefficients, |a2| and |a3|. Furthermore, the famous Fekete–Szegö inequality is obtained for the newly defined subclasses of bi-univalent functions. Several consequences of our results are pointed out which are new and not yet discussed in association with bounded boundary rotation. Some improved results when compared with those already available in the literature are also stated as corollaries.

FUZZY DIFFERENTIAL SUBORDINATION INVOLVING GENERALIZED NOOR-RUSCHEWEYH OPERATOR

A new operator Lnλ is introduced as a convex combination of Ruscheweyh derivative operator and Noor integral operator on the class A of analytic functions in the open unit disc E. The operator Lnλ is studied using fuzzy set theory and fuzzy differential subordination. All the results proved are sharp. Some interesting special cases are derived as corollaries for particular choices of the functions acting as fuzzy best dominant.

A New Class of Univalent Functions Defined by Differential Operator

In the present work, we submit and study a new class $\mathcal{S}_{\lambda, \alpha, b}^{z, m, t}(\beta, \gamma, \omega, \mu)$ containing analytic univalent functions defined by new differential operator $D_{\lambda, \alpha}^{z, m, t}$ in the open unit disk $E=\{s \in \mathbb{C}:|s|<1\}$. We get some geometric properties, such as, coefficient estimate, growth and distortion theorems, convex set, radii of convexity and starlikeness, weighted mean, arithmetic mean and partial sums for functions belonging to the class $\mathcal{S}_{\lambda, \alpha, b}^{z, m, t}(\beta, \gamma, \omega, \mu)$.

New Class of Multivalent Functions Defined by Generalized (p,q)-Bernard Integral Operator

Making use of the generalized $(p, q)$-Bernardi integral operator, we introduce and study a new class $\mathcal{F J}_{p, q}^m(\alpha, \delta, \lambda, \gamma)$ of multivalent analytic functions with negative coefficients in the open unit disk $E$. Several geometric characteristics are obtained, like, coefficient estimate, radii of convexity, close-to-convexity and starlikeness, closure theorems, extreme points, integral means inequalities, neighborhood property and convolution properties for functions belonging to the class $\mathcal{F} \mathcal{J}_{p, q}^m(\alpha, \delta, \lambda, \gamma)$.

New Class of Multivalent Functions Defined by Generalized (p,q)-Bernard Integral Operator

Making use of the generalized $(p, q)$-Bernardi integral operator, we introduce and study a new class $\mathcal{F J}_{p, q}^m(\alpha, \delta, \lambda, \gamma)$ of multivalent analytic functions with negative coefficients in the open unit disk $E$. Several geometric characteristics are obtained, like, coefficient estimate, radii of convexity, close-to-convexity and starlikeness, closure theorems, extreme points, integral means inequalities, neighborhood property and convolution properties for functions belonging to the class $\mathcal{F} \mathcal{J}_{p, q}^m(\alpha, \delta, \lambda, \gamma)$.