Abstract
The main aim of this research paper is to introduce a new extension of the Gauss hypergeometric function and confluent hypergeometric function by using an extended beta function. Some functional relations, summation relations, integral representations, linear transformation formulas, and derivative formulas for these extended functions are derived. We also introduce the logarithmic convexity and some important inequalities for extended beta function.
Keywords:
classical Euler beta function; gamma function; Gauss hypergeometric function; confluent hypergeometric function; Mittag-Leffler function MSC:
33B15; 33C05; 33C15; 33E12
1. Introduction and Preliminaries
The theory of special functions, especially extensions of beta function, gamma function, hypergeometric functions has been one of the fastest rising investigate a topic in mathematical science because scientific researchers feel it is important to study the behavior of special functions with extended domains. Special functions are naturally generalizations of the elementary functions and they play a vital role in the solution of the differential equations due to which study of the generalizations of the special functions always important. In the past years, many extensions, properties, and applications of special functions have been discussed by many researchers and authors [1,2]. Here, we aim to study some results of the extended beta function and hypergeometric functions by using Wiman’s function.
To obtain our main results, we require prior knowledge of some special functions. First of all, throughout this present paper, there is a need to note the following notations: represents the real part of any complex number z, C represents a set of complex numbers, and represents a set of positive real numbers.
Classical Euler beta function and gamma function are defined as [3]:
where and ;
where .
Gauss hypergeometric function is defined as [4]:
where represents the Pochhammer symbol defined below:
Series representation and integral representation of Gauss hypergeometric function is defined as [4]:
where and .
Confluent hypergeometric function is defined as [4]:
Series representation and integral representation of confluent hypergeometric function is defined as [4]:
where ;
One parameter Mittag-Leffler function and two parameter Mittag-Leffler function (Wiman’s function) is defined as [5,6,7]:
where and ;
where , and .
Since 1900, many researchers have been working on extensions of special functions. Chaudhry is one of the mathematician who continuously worked on extensions of beta function and other special functions. In 1997, Chaudhry et al. extended the classical Euler beta function defined in Reference [8], and then, in 2004, he used this extended beta function to generalize the Gauss hypergeometric function and confluent hypergeometric function as [9]:
where , and ;
where , , ;
where and .
Remark 1.
Subsequently, Özergin et al. [10] have used confluent hypergeometric function to extend classic Euler beta function; moreover, the latter function was then exploited to generalize hypergeometric functions as follows:
where , and ;
where , and ;
where and .
Later, in 2014, Choi et al. [11] defined a generalization of extended beta function reported in (11), using it to broaden the definition of extended hypergeometric Gauss function and extended confluent hypergeometric as follows:
where , and ;
where , , and ;
where , and .
Remark 2.
In 2018, Shadab et al. [12] extended classic Euler beta function using one parameter Mittag-Leffler function; this generalization was then exploited to expand hypergeometric function of the Gauss and confluent hypergeometric function, thus allowing to study various properties and relationships of these functions:
where , and ;
where , , and ;
where , and .
Remark 3.
(i) If we set in (25) and (26), we get extended Gauss hypergeometric function and extended confluent hypergeometric function given by (12) and (13), respectively:
and
(ii) If we set and in (25) and (26), we get Gauss hypergeometric function and confluent hypergeometric function given by (4) and (7), respectively:
and
Very recently, Goyal et al. [13] introduced an extension of the beta function using the Wiman function, thus studying various properties and relationships of that function:
where , , and is 2-parameter Mittag-Leffler function given by (10).
In this paper, we discuss convexity and inequalities related to extended beta function given in (31). Now, we give some definitions about convex functions and show some results.
Definition 1.
(References [14,15]) Let Y be a convex set in a real vector space, and letbe a function. Then, g is called convex on Y if the inequality
holds for any and .
The function g is concave if the function is convex.
The function g is called logarithmically convex (or logarithmically concave, respectively) on Y if and ( , respectively) is convex (or concave, respectively) on Y.
Lemma 1.
(References [16,17,18]) (Chebyshev’s integral inequality)
Let be integrable functions. Assume that:
Let be a positive integrable function. Then:
Lemma 2.
(References [19,20]) (Hölder Inequality) Let and be positive numbers such that
Let be integrable functions. Then
2. Inequalities of Extended Beta function
Theorem 1.
Assume that:
- are non-zero and non-negative numbers such that ,
- and .
Then,
Proof.
Let be functions such that
Since
functions and have the same monotonicity (increasing or decreasing) on as .
Then, applying Chebyshev’s inequality given in (33), to , , and , we have:
□
Corollary 1.
Assuming that , and , then:
Proof.
Put and in theorem (1). Using symmetry property of extended beta function , we get our desired result:
□
Theorem 2.
The map is logarithmically convex on , with and . Moreover:
Proof.
Let and let with .
After some algebraic manipulation on the left-hand side terms of the extended beta function (31), we get
Then, from Definition (1), the function is logarithmically convex on .
If , we get our desired result:
□
3. Extension of Gauss Hypergeometric Function and Confluent Hypergeometric Function
In this section, we introduce a new extension of Gauss hypergeometric function and confluent hypergeometric function by using extended beta function given in (31). In integral representation of Gauss hypergeometric function and confluent hypergeometric function, we introduce Wiman’s function as a kernel.
Definition 2.
A new extended Gauss hypergeometric function is defined as follows:
where , , , and extended beta function.
After substitution of beta function value in terms of gamma function
in the above definition, we have another representation of a new extended Gauss hypergeometric function (39):
Definition 3.
A new extended confluent hypergeometric function is defined as follows:
where , , and extended beta function.
After substitution of beta function value in terms of gamma function, in the above definition, we have another representation of a new extended confluent hypergeometric function (41):
where , and
Definition 4.
(New) A new form of beta function is defined as:
Using the above relation, we have a new form of extended Gauss hypergeometric function and extended confluent hypergeometric function :
and
Remark 4.
We know that Gauss’s hypergeometric function does not change if the and parameters are swapped while keeping fixed. This symmetric property with respect to the parameters and can also be deduced from the new extended Gauss hypergeometric function (39):
The beta function (43) can be rewritten in a similar form:
Using the above relation (48), we can rewrite extended Gauss hypergeometric functionin a similar form:
Remark 5.
(i) If we setin (39) and (41), then, we get a new extension of Gauss hypergeometric function and confluent hypergeometric function given by (25) and (26), respectively:
and
(ii) If we set in (39) and (41), then we get extended Gauss hypergeometric function and extended confluent hypergeometric function given by (12) and (13), respectively:
and
(iii) If we set and in (39) and (41), then we get Gauss hypergeometric function and confluent hypergeometric function given by (3) and (6), respectively:
and
Theorem 3.
Consider and functions. Then, the following functional relations hold:
(1)
where , , and .
(2)
where , and .
Proof.
Then, using the value of beta function in terms of gamma function together with (39), allow us to get the desired result.
Remark 6.
we obtain another functional relation for :
Theorem 4.
Consider and functions. The following Sum relations hold:
(1)
where , , and .
(2)
where , and .
Proof.
Moreover, from (39)
Using value of beta function in terms of gamma function and value of gamma function in terms of Pochhammer symbol in the above equation, we get our desired statement:
Remark 7.
Theorem 5.
Consider and functions. The following Sum relations hold:
(1)
where , , , , and .
(2)
where , , , and .
Proof.
Remark 8.
we have another summation relation for :
Theorem 6.
Consider and functions. The following results hold:
(1)
where , , , and .
(2)
where , , and .
Proof.
From (39), we get our desired result:
Remark 9.
Theorem 7.
Consider and functions. The following integral representations hold:
(1)
where , , and .
(2)
where , and .
Proof.
Changing the order of integration and summation, we get:
Since
the last expression becomes the searched result:
Remark 10.
From (46), we observe that, for , the following integral representation holds:
Corollary 2.
Consider and functions. The following integral representations hold:
(1)
(2)
Corollary 3.
Consider and functions. The following integral representations hold:
(1)
(2)
Theorem 8.
The Mellin Transformations for and are given by:
(1)
where , , , and .
(2)
where , , and .
Proof.
From the definition of Mellin Transformation, we have:
Using (77) on the right-hand side, we have
Interchanging the order of integrations, the last expression reads as:
Let . Then:
From the known result in Reference [21]:
and, using it with in the above equation, we get
Finally, from integral representation of Gauss hypergeometric function (5), we get our desired result:
Remark 11.
Theorem 9.
The Pfaff’s transformations for is given by:
(1)
where , , and .
(2)
where , , and .
Proof.
From (77), we deduce:
Let . After some algebraic manipulation, the last expression reads as:
Thus, we get our desired result (91):
Moreover, using same property (46) on the right-hand side of the above equation, we get our statement (92):
□
Theorem 10.
The Euler’s transformation for is given by:
where , , and .
Proof.
Now, replacing with and z with , we complete the theorem’s proof:
□
Theorem 11.
For , we obtain the extension of Kummer transformation:
where , and .
Proof.
From (78), we get:
Let . After some algebraic manipulation, the last expression becomes:
Theorem 12.
Consider function. The following relation holds:
where , , and .
Proof.
Multiplying by and integrating the above equation with respect to z from to , we get:
Using (41) on the right-hand side of last expression, we obtain:
Then, changing order of integration and summation, we can read:
From definition of gamma function and from its relation with Pochhammer symbol
we obtain:
Finally, from (39), we get our desired result:
□
Theorem 13.
Consider and functions. The following differentiation formulas hold:
(1)
where , , , and .
(2)
where , , and .
Proof.
Replacing with m, we can read:
Using the property of Pochhammer symbol , and after manipulation, we obtain:
By exploiting (39), we get our statement:
4. Conclusions
We conclude our analysis by mentioning that the results obtained in this paper are new and potentially useful. First, we have investigated some inequalities of the extended beta function. Then, we have introduced a new extension of Gauss hypergeometric and confluent hypergeometric function and investigated some properties of these extended functions. We are also trying to find certain applications of the results obtained here in some significant research areas, such as statistics, physics, engineering, applied mathematics, and computer algebra. In the future, we will work on matrix forms of these extended functions and also try to develop algorithms for these extended functions by using maple computer software.
Author Contributions
Conceptualization, S.J. and R.G.; methodology, P.A.; software, S.J. and R.G.; validation, S.J., R.G., P.A., A.L. and C.C.; investigation, C.C.; formal analysis, P.A. and C.C.; resources, P.A.; data writing—original draft preparation, S.J.; writing-review and editing, S.J., R.G., P.A. and C.C.; visualization, P.A.; funding acquisition, P.A. and C.C. All authors have read and agreed to the published version of the manuscript.
Funding
Shilpi Jain is very thankful to SERB (project number: MTR/2017/000194) for providing the necessary facility and support during this work.
Acknowledgments
Shilpi Jain is very thankful to SERB (project number: MTR/2017/000194) for providing the necessary facility and support during this work and Rahul Goyal and Praveen Agarwal are thankful to NBHM(project number: 02011/12/2020NBHM(R.P)/R&DII/7867).
Conflicts of Interest
The authors declare no conflict of interest.
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