Abstract
In this paper, the authors define a new generic class of functions involving a certain modified Fox–Wright function. A useful identity using fractional integrals and this modified Fox–Wright function with two parameters is also found. Applying this as an auxiliary result, we establish some Hermite–Hadamard-type integral inequalities by using the above-mentioned class of functions. Some special cases are derived with relevant details. Moreover, in order to show the efficiency of our main results, an application for error estimation is obtained as well.
1. Introduction and Preliminaries
In many problems in mathematics and its applications, fractional calculus has a crucial role (see [1,2,3,4,5,6]). The analysis of the uniqueness of fractional ordinary differential equations can be accomplished by using fractional integral inequalities (see [7,8,9]).
Integral inequalities play a major role in the fields of differential equations and applied mathematics (see [10,11]). Moreover, they are linked with such other areas as differential equations, difference equations, mathematical analysis, mathematical physics, convexity theory, and discrete fractional calculus (see [12,13,14,15,16,17,18]).
Convexity is a fascinating and natural concept; it is beneficial in optimization theory, the theory of inequalities, numerical analysis, economics, and in other fields of pure and applied mathematics.
The notion of the h–convex function is introduced below.
Definition 1.
(see [19]). Let be a function. A function is said to be h–convex if
holds true for every and
The following class of functions was introduced by Awan et al. (see [20]) and was demonstrated to play an important role in optimization theory and mathematical economics.
Definition 2.
A function is called exponentially convex if
holds true for all and
The most significant inequality about a convex function on the closed interval is the Hermite–Hadamard integral inequality (that is, the trapezium inequality). This two-sided inequality is expressed as follows:
The two-sided inequality (1) has become a very important foundation within the field of mathematical analysis and optimization. Several applications of inequalities of this type have been derived in a number of different settings (see [21,22,23,24,25,26,27,28,29]).
In the context of fractional calculus, the standard left and right-sided Riemann–Liouville () fractional integrals of order are given, respectively, by
where is a function defined on the closed interval and is the classical (Euler’s) gamma function.
Regarding information for some of the fractional integral operators, including those that are known as Erdélyi–Kober, Riemann–Liouville (), Weyl and Liouville–Caputo () operators, see [30,31,32,33,34].
There are many directions in which one can introduce a new definition of fractional derivatives and fractional integrals, which are related to or inspired by (for example) the definitions (see [35,36]), with reference to some general classes into which such fractional calculus operators can be classified. In applied mathematics, it is important to consider particular types of fractional calculus operators which are suited to the fractional-order modeling of a given real-world problem.
We now recall the familiar Fox–Wright hypergeometric function (with p numerator and q denominator parameters), which is given by the following series (see [5] (p. 67, Equation (1.12(68))) and [37] (p. 21, Equation (1.2(38)))):
where the parameters
and the coefficients
satisfy the following condition:
Here and in what follows, we have made use of the general Pochhammer symbol defined by
it being assumed conventionally that and understand tacitly that the -quotient in (5) exists.
The following modified version of the Fox–Wright function in (3) was introduced, as long ago as 1940, by Wright [38] (p. 424), who partially and formally replaced the -quotient in (3) by a sequence based upon a suitably-restricted function as follows (see also [39], where the same definition is reproduced without giving credit to Wright [38]):
If, in Wright’s definition (6) from 1940 (see [38] (p. 424)), we take and
then Wright’s definition (6) would immediately yield the familiar Fox–Wright hypergeometric function defined by (3). The one- and two-parameter Mittag–Leffler functions and , and indeed also almost all of the parametric generalizations of the Mittag–Leffler type functions, can be deduced as obvious special cases of the Fox–Wright hypergeometric function defined by (3) (see [40] for details).
We are now in the position to introduce a new generic class of functions involving the modified Fox–Wright function
Definition 3.
Let be two functions and If ψ satisfies the following inequality,
for all and where then ψ is called an exponentially –nonconvex function.
Remark 1.
Upon setting
and
in Definition 3, we then obtain Definition 2.
Remark 2.
Some special cases of our Definition 3 are listed below:
- (I)
- Taking we have an exponentially –nonconvex function.
- (II)
- Choosing and , we obtain an exponentially –nonconvex function.
- (III)
- Setting and for we obtain an exponentially –Breckner-nonconvex function.
- (IV)
- Putting and for we obtain an exponentially –Godunova–Levin–Dragomir-nonconvex function.
- (V)
- Taking we obtain an exponentially –nonconvex function.
Our paper has the following structure: in Section 2, we first find a useful identity using fractional integrals with two parameters and involving the modified Fox–Wright function Applying this as an auxiliary result, we give some Hermite–Hadamard-type integral inequalities pertaining to exponentially –nonconvex functions, and some special cases are derived in details. In Section 3, the efficiency of our main results is demonstrated with an application for error estimation. Section 4 presents the conclusion of this paper.
2. Main Results and Their Consequences
The following notations are used below:
where
and is the interior of the closed interval with We denote by the space of integrable functions over We need to prove the following basic lemma.
Lemma 1.
Let the function be differentiable on and If then, for
Proof.
From Lemma 1, we can derive the following case:
Remark 3.
Taking in Lemma 1, we have
Our first main result is stated as Theorem 1 below.
Theorem 1.
Assume that are two continuous functions and let be a differentiable function on with Furthermore, let If is an exponentially –nonconvex function, then, for and it is asserted that
where
Proof.
Applying Lemma 1, the property of the modulus, Hölder’s inequality, and the exponential –nonconvexity of we have
which completes the proof of Theorem 1. □
Some corollaries and consequences of Theorem 1 are listed below:
Corollary 1.
Upon setting Theorem 1 yields
Corollary 2.
Choosing in Theorem 1 it is asserted that
Corollary 3.
Choosing
in Theorem 1 it is asserted that
where
Corollary 4.
Taking
in Theorem 1 the following inequality is deduced:
where
Corollary 5.
For
Theorem 1 yields
where
Our second main result is stated as Theorem 2 below.
Theorem 2.
Assume that are two continuous functions and is a differentiable function on with Furthermore, let If be an exponentially –nonconvex function; then, for and it is asserted that
where
Proof.
Applying Lemma 1, the property of the modulus, power-mean inequality and the exponential -nonconvexity of we obtain
The proof of Theorem 2 is completed. □
We now state several corollaries and consequences of Theorem 2.
Corollary 6.
Upon setting Theorem 2 yields
where
Corollary 7.
Choosing in Theorem 2 the following inequality holds true:
Corollary 8.
Choosing
Theorem 2 is reduced to the following inequality:
where
Corollary 9.
By putting
Theorem 2 yields the following inequality:
where
Corollary 10.
Upon letting
Theorem 2 yields the following inequality:
where
and
Remark 4.
If we take or or and in Theorem 1 and Theorem 2, then we can obtain some interesting results immediately. We omit their proofs here, and the details are left to the interested reader.
Remark 5.
If we choose in our results in this paper, then all of the consequent results will hold true for the –nonconvex functions.
3. Application
In this section, we present an application involving a new error estimation for the trapezoidal formula by using the inequalities obtained in Section 2. We fix the parameters and . We also suppose that the bounded sequence of positive real numbers is given.
Let
be a partition of the closed interval
For let us define
and
where is the remainder term and
From the above notations, we can obtain some new bounds regarding error estimation.
Proposition 1.
Assume that are two continuous functions. Furthermore, let be a differentiable function on with . Suppose that and that is an exponentially –nonconvex function. Then, for and it is asserted that
Proof.
Applying Theorem 1 on the subinterval of the closed interval and taking we obtain
Proposition 2.
Assume that are two continuous functions. Furthermore, let be a differentiable function on with Suppose that and that is an exponentially –nonconvex function. Then, for the following inequality holds true:
Proof.
Choosing in Theorem 2 and using the same technique as in our demonstration of Proposition 1, we obtain the desired inequality (26). □
Remark 6.
In view of Remark 2 we can establish new error estimations by using Proposition 1 and Proposition 2
4. Conclusions
In this paper, the authors have defined a new generic class of functions involving the modified Fox–Wright function as well as the so-called exponentially –nonconvex function. A useful identity has also been found by using fractional integrals and the function with two parameters and . We have established some Hermite–Hadamard-type integral inequalities by using the above class of functions and the aforementioned identity as an auxiliary result. Several special cases have been deduced as corollaries including relevant details. We have also outlined the derivations of several other corollaries and consequences for the interested reader. The efficiency of our main results has been shown by proving an application for error estimation.
Author Contributions
Conceptualization, H.M.S., A.K., P.O.M., D.B.; methodology, H.M.S., P.O.M., Y.S.H.; software, P.O.M., Y.S.H., A.K.; validation, P.O.M., Y.S.H.; formal analysis, P.O.M., Y.S.H., D.B.; investigation, H.M.S., P.O.M.; resources, P.O.M., A.K.; data curation, D.B., Y.S.H.; writing—original draft preparation, H.M.S., A.K., P.O.M.; writing—review and editing, D.B., Y.S.H.; visualization, Y.S.H.; supervision, H.M.S., Y.S.H., D.B. All authors have read and agreed to the final version of the manuscript.
Funding
This research received no external funding.
Institutional Review Board Statement
Not applicable.
Informed Consent Statement
Not applicable.
Data Availability Statement
Not applicable.
Acknowledgments
This research was supported by Taif University Researchers Supporting Project (No. TURSP-2020/155), Taif University, Taif, Saudi Arabia.
Conflicts of Interest
The authors declare no conflict of interest.
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