Abstract
In this article, we use the concept of symmetric q-calculus and convolution in order to define a symmetric q-differential operator for multivalent functions. This operator is an extension of the classical Ruscheweyh differential operator. By using the technique of differential subordination, we derive several interesting applications of the newly defined operator for multivalent functions.
Keywords:
analytic functions; symmetric q-calculus; symmetric q-differential operator; multivalent functions; convolution; subordination MSC:
30C45; 30C50
1. Introduction
The study of q-calculus has motivated scholars due to its wide range of applications in different areas of mathematics and physics. Jackson [1,2] was the first to consider the q-calculus theory in order to define the q-derivative and the q-integral operator. Meanwhile, in [3], Ismail et al. used and defined q-starlike functions in the field of Geometric function theory and investigated some interesting applications. Later on, Srivastava [4], used the q-calculus in the context of univalent functions theory and he developed many important results. The q-analogue of Ruscheweyh differential operator was introduced by Kanas and Raducanu [5] while in [6], Srivastava et al. introduced the q-Noor integral operator and studied some of its applications for bi-univalent functions. In particular, Srivastava [7,8] pointed out many applications and mathematical explanations of q-derivatives in Geometric function theory. In recent years, many researchers have defined a number of q-differential and integral operators and have published many important results associated with q-starlike and the Janowski functions (for details, see [9,10,11,12,13,14]).
Let and be the q-number for and be the factorial and
The q-Gamma function is defined as:
Jackson [1] defined the q-difference operator for analytic functions in the following form:
Additionally, we have
It can be observed that
The symmetric q-calculus has been found to be very useful in different areas, such as fractional calculus and quantum mechanics. The applications of quantum mechanics are discussed in q-symmetric variational calculus in [15] while in [16], Lavagno discussed the symmetric q-calculus in the field of basic-deformed quantum mechanics. More recently, Kanas et al. [17] investigated some new applications of the symmetric q-derivative related to the conic domain and studied a new subclass of analytic functions in the open unit disk U. Khan et al. [18] investigated the new version of generalized symmetric conic domains using the basic concepts of symmetric q-calculus and studied a new subclass of q-symmetric starlike functions. Recently, a number of authors used the q-symmetric operator and studied some new subclasses of analytic functions, (see [19,20,21]). Here, we present the basic concepts of symmetric q-calculus, which will be useful for our subsequent work.
The symmetric q-number can be defined as:
and the symmetric q-number shift factorial is given by
It can be noted that
It is worth mentioning that the symmetric q-number cannot reduce to q-number.
Kamel and Yosr [22] defined the symmetric q-derivative operator for the analytic function, which can be written as follows:
and
It can be observed that
Let represents the set of all functions p, which satisfies the conditions and . Let and be analytic in U. If there exists a Schwarz function u, such that , then we will say that is subordinate to (written as for .
Assume that denote the class of multivalent functions of the form:
The convolution of two functions for is defined as:
where
Janowski [23] defined the function The image of the unit disc under the mapping is the disk symmetrical with respect to the real axis, with its center at for , and the end points of the diameter are
In our current investigation, we aim to use basic concepts of symmetric q-calculus and the convolution theory to define a new operator for multivalent analytic functions.
Definition 1.
Let Then, the symmetric q-differential operator is defined as:
where
By using the definition of convolution, it can be noted that
From (3), the following identity can be easily verified:
For , and Identity (4), implies that
which is the well-known relation studied by Ruscheweyh in [24].
Remark 1.
If and , the q-differential operator reduces to the Ruscheweyh differential operator introduced by Ruscheweyh in [24].
2. Lemmas
To prove our main results, we need the following Lemmas:
Lemma 1
([11]). If an analytic function and
then
Lemma 2
Lemma 3
Lemma 4
([27]). The function
is univalent in if and only if γ is either in closed disk
We can prove Lemmas 5 and 6 using the similar method of Lemmas proved in [11].
Lemma 5.
Let be analytic and convex univalent in with . Additionally, let be analytic in . If
then
Proof.
Suppose that is analytic and convex univalent in and is analytic in . Letting in (6)
Then, from Lemma in [28], we obtain
□
Lemma 6.
Let be univalent in and let and be analytic in domain D containing with when Set
and suppose that
- (i)
- is starlike univalent in ℑ.
- (ii)
- .
If is analytic in , with , , and
then and is the best dominant.
Proof.
We can prove Lemma 6 using a method similar to the one shown in Lemma 5. □
3. Main Results
Theorem 1.
Let , and . If satisfies
then
where
Proof.
Let
For , and by taking the logarithmic differentiation of (10), we get
Using the identity (4), we get
Let . Then,
From (4), (10) and (11), we have
Now, by applying the Lemma 5, we have
Using the definition of subordination, we get
In view of and , it follows from (13) that
Since
Therefore, the inequality (9) is proved.
To show the sharpness of (9), we define as:
For this function, we find that
So,
This completes the proof. □
Corollary 1.
Let , and . If satisfies
then
Corollary 2.
Let , and . If satisfies
then
Corollary 3.
Let and If satisfies
then,
Proof.
Following the same steps detailed in the proof of Theorem 1 and by considering
the differential subordination (12) becomes
Therefore,
□
Theorem 2.
Let and and γ be a complex number with satisfying either
or
If satisfies the condition
then
Proof.
Let
Assume that
Then, is univalent and we will show that , , and satisfy the conditions of Lemma 6. Note that the function
is univalent starlike in U and
By using the Lemma 6, we obtain the required result. □
Corollary 4.
Let and . Let γ be a complex number with that satisfies either
or
If satisfies the condition
Then,
Theorem 3.
Let , and −1. If each of satisfy
then
where
and
4. Conclusions
By taking inspiration from recent studies on q-calculus and convolution operators for univalent functions, we have defined a new convolution operator for multivalent analytic functions. This newly defined operator for multivalent functions is an extension of the classical Ruscheweyh derivative operator. In this paper, we have successfully derived several properties for a class of multivalent analytic functions connected with a new operator by using the subordination theory. We also highlighted some consequences of our main results, which are stated in the form of corollaries.
Author Contributions
These authors contributed equally to this work. All authors have read and agreed to the published version of the manuscript.
Funding
This work was supported by the Deanship of Scientific Research, the Vice Presidency for Graduate Studies and Scientific Research, King Faisal University, Saudi Arabia (Grant No. 2317).
Data Availability Statement
No new data were created or analyzed in this study. Data sharing is not applicable to this article.
Acknowledgments
The authors would like to thank the editor and the anonymous reviewers for their constructive comments and suggestions, which helped us to improve the manuscript. This work was supported by the Deanship of Scientific Research, the Vice Presidency for Graduate Studies and Scientific Research, King Faisal University, Saudi Arabia (Grant no. 2317).
Conflicts of Interest
The authors declare that they have no competing interest regarding the publication of this paper.
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