Some Results on Hermite-Hadamard Type Inequality through Convexity
Shahid Qaisar1, Sabir Hussain1,
1College of Mathematics and Statistics, Chongqing University, Chongqing, P. R. China
Abstract
Our aim in this article to establish various inequalities for some differentiable mapping that are connected with illustrious Hermite-Hadamard integral inequality for mapping whose absolute values of derivatives are convex. The new integral inequalities are then applied to some special means and as well as numerical integration to obtain some better estimates.
Keywords: Hermite-Hadamard type inequality, convex functions, special means, Hölder’s integral inequality, power-mean inequality, Quadrature formula
Turkish Journal of Analysis and Number Theory, 2014 2 (2),
pp 53-59.
DOI: 10.12691/tjant-2-2-5
Received March 05, 2014; Revised April 13, 2014; Accepted April 21, 2014
Copyright © 2013 Science and Education Publishing. All Rights Reserved.Cite this article:
- Qaisar, Shahid, and Sabir Hussain. "Some Results on Hermite-Hadamard Type Inequality through Convexity." Turkish Journal of Analysis and Number Theory 2.2 (2014): 53-59.
- Qaisar, S. , & Hussain, S. (2014). Some Results on Hermite-Hadamard Type Inequality through Convexity. Turkish Journal of Analysis and Number Theory, 2(2), 53-59.
- Qaisar, Shahid, and Sabir Hussain. "Some Results on Hermite-Hadamard Type Inequality through Convexity." Turkish Journal of Analysis and Number Theory 2, no. 2 (2014): 53-59.
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1. Introduction
The role of mathematical inequalities within the mathematical branches as well as in its various application should not be underestimated. The appearance of the new mathematical inequality often puts on the firm foundation for the heuristic algorithms and techniques utilized within applied sciences. Among other one of the main inequality, which provides for us an explicit error bounds in the trapezodial and midpoint rules of a smooth function, called Hermite-Hadamard’s inequality defined as [[1], p. 53]:
![]() | (1.1) |
where is a convex function. Both inequalities hold in the reversed direction for f to be concave. We note that Hermite-Hadamard’s inequality may be regarded as a refinement of the concept of convexity and it follows easily from Jensen inequality. Inequality (1.1) has received renewed attention in recent years and a remarkable variety of refinements and generalization have been discovered [2, 7, 10, 11] and the refrences cited therein.
Theorem 1.1. ([3]) Let be a differentiable function on
(interior of
)
with
if the mapping
is convex on
and then we have the following inequality:
![]() | (1.2) |
Theorem 1.2. ([3]) Let be a differentiable function on
(interior of
)
with
if the mapping
is convex on
for some fixed p>1 and then we have the following inequality:
![]() | (1.3) |
In similar manner to Dragomir and Agarwal methodology, inequalities for differentiable convex mappings associated with the left-hand side of Hermite-Hadamard’s (midpoint) inequality was verified by Kirmaci ,by means of the following illustration:
Theorem 1.3. ([5]) Let be a differentiable mapping on
with
If
is convex on [a,b] then we have:
![]() | (1.4) |
Theorem 1.4. ([4]) Let be a differentiable function on
(interior of
)
with
If the mapping
is convex on
for some fixed p>1,and then we have the following inequality:
![]() | (1.5) |
Theorem 1.5. ([4]) Let be a differentiable function on
(interior of
)
with
If the mapping
is convex on
for some fixed
and
is a linear map, we have the following inequality:
![]() | (1.6) |
In most recent years, For additional findings relating to the Hermite-Hadamard integral inequality for utilizing different kind of convexity, readers are directed to ([12-17][12]). This work is organized in the following way. After this Introduction, in Section 2 main results are presented.In Section 3 application to special means are considered. Finally Section 4, error is estimated for the generalized quadrature formula.
2. Main results
To prove our main result, we need some important lemma.
Lemma 2.1. Let be differentiable function on
where
is with
If
Then the following inequality holds:
![]() | (2.1) |
Proof. Using integrating by parts, and by making use of the substitution
![]() |
we have
![]() |
analougusoly,
![]() |
This proves as required.
Theorem 2.2. Let be a differentiable function on
where
is with
such that
If the mapping
is convex on
then we have the following inequality:
![]() | (2.2) |
Proof. Using Lemma 2.1 and taking the modulus, we have
![]() |
using the convexity of |f’|, we have
![]() | (2.3) |
![]() | (2.4) |
![]() | (2.5) |
![]() | (2.6) |
Combing the above inequalities (2.3), (2.4), (2.5), and (2.6), we obtain (2.2). This completes the proof.
Corollary 2.3 Under the conditions of Theorem 2.2,
![]() |
Using the convexity of for all
we have
![]() |
Proof . The assertion follows from Theorem 2.2 and utilizing the convexity of |f’|.
Theorem 2.4 Let be a differentiable function on
where
is with
such that
If the mapping
is convex on
then we have the following inequality:
![]() | (2.7) |
Proof. Using Lemma 2.1 and Hölder inequality we have
![]() |
using the convexity of , we have
![]() | (2.8) |
![]() | (2.9) |
![]() | (2.10) |
![]() | (2.11) |
Combing the above inequalities (2.8), (2.9), (2.10), and (2.11), we obtain (2.7). This completes the proof.
Theorem 2.5 Let be a differentiable function on
where
is with
such that
If the mapping
is convex on
for some fixed
then we have the following inequality:
![]() | (2.12) |
Proof. Using Lemma 2.1 and power mean inequality we have
![]() |
using the convexity of ,we have
![]() | (2.13) |
![]() | (2.14) |
![]() | (2.15) |
![]() | (2.16) |
Combing the above inequalities (2.13), (2.14), (2.15), and (2.16), we obtain (2.12). This completes the proof.
Theorem 2.6 Let be a differentiable function on
where
is with
such that
If the mapping
is concave on
for some fixed q>1, then we have the following inequality:
![]() | (2.17) |
Proof. Using Lemma 2.1 and well known Hölder inequality we have
![]() |
using the convexity of ,we have
![]() | (2.18) |
![]() | (2.19) |
![]() | (2.20) |
![]() | (2.21) |
Combing the above inequalities (2.18), (2.19), (2.20), and (2.21), we obtain (2.17). This completes the proof.
Corollary 2.7 Under the conditions of Theorem 2.6, assume that function is a linear map,
![]() |
Proof. It is a direct consequence of Theorem 2.6 and using the linearity of the function.
Theorem 2.8 Let be a differentiable function on
where
is with
such that
If the mapping
is concave on
for some fixed
then we have the following inequality:
![]() |
Proof. By the concavity of and Power-mean inequality we have
![]() |
And thus
![]() |
Using Lemma 2.1 and the Jensen’s integral inequality, we have
![]() |
Corollary 2.9 Under the conditions of Theorem 2.8,
![]() |
Proof. The assertion is a direct consequence of Theorem 2.8 and using the linearity of function.
3. Application to Some Special Means
Let us recall the following means for arbitrary real numbers a and b.
The Arithmetic mean
![]() |
The Harmonic mean
![]() |
Generalized-logarithmic mean
![]() |
The Logarithmic mean
![]() |
Now utilizing outcomes of Section 2, some new inequalities are derived for the above means.
Proposition . Let ,
and
then, we have
![]() | (3.1) |
Proof. By corollory 2.3 applied for the mapping
, we have the above inequality (3.1).This completes the proof.
Proposition . Let,
and
then, we have
![]() | (3.2) |
Proof. By corollory 2.3 applied for the mapping
, we have the above inequality (3.2). This completes the proof.
4. Application to Quadrature Formula
Let D be the partition of the interval [a,b], and consider the quadrature formula
![]() |
where
![]() |
For the quadrature version and denotes the approximation error.
Proposition 4.1. Let be a differentiable mapping on
(interior of
)
with
If the mapping
is convex on
then for every division
of
the following holds:
![]() | (4.1) |
Proof. Using Theorem 2.2 on the subintervals
of the division
we have
![]() | (4.2) |
![]() | (4.3) |
By combining (4.2) and (4.3), we obtain (4.1). This completes the proof.
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![]() | CrossRef | ||
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