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Publications Influence

Three families of two-parameter means constructed by trigonometric functions

- Zhen-Hang Yang
- Mathematics
- 19 November 2013

In this paper, we establish three families of trigonometric functions with two parameters and prove their monotonicity and bivariate log-convexity. Based on them, three two-parameter families of… Expand

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Some properties of the divided difference of psi and polygamma functions

- Zhen-Hang Yang
- Mathematics
- 1 November 2017

Abstract Let ψ n = ( − 1 ) n − 1 ψ ( n ) for n ≥ 0 , where ψ ( n ) stands for the psi and polygamma functions. For p , q ∈ R and ρ = min ( p , q ) , let D [ x + p , x + q ; ψ n − 1 ] ≡ − ϕ n ( x )… Expand

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The monotonicity and convexity for the ratios of modified Bessel functions of the second kind and applications

- Zhen-Hang Yang, S. Zheng
- Mathematics
- 23 January 2017

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Necessary and Sufficient Condition for Schur Convexity of the Two-Parameter Symmetric Homogeneous Means

- Zhen-Hang Yang
- Mathematics
- 2011

An necessary and sufficient condition for Schur convexity of the two-parameter symmetric homogeneous means is given, which improves Witkowski's result. As an application, Schur convexity of the… Expand

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On approximating the arithmetic-geometric mean and complete elliptic integral of the first kind

- Zhen-Hang Yang, W. Qian, Yu-Ming Chu, W. Zhang
- Mathematics
- 15 June 2018

Abstract In the article, we prove that the double inequalities 1 + ( 6 p − 7 ) r ′ p + ( 5 p − 6 ) r ′ π tanh − 1 ( r ) 2 r K ( r ) 1 + ( 6 q − 7 ) r ′ q + ( 5 q − 6 ) r ′ π tanh − 1 ( r ) 2 r ,… Expand

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Sharp Gautschi inequality for parameter 0

- Zhen-Hang Yang, E. Zhang, Y. Chu
- Mathematics
- 2017

In the article, we present the best possible parameters a,b on the interval (0,∞) such that the Gautschi double inequality [(xp +a) − x]/a < ex ∫ ∞ x e−t p dt < [(xp +b) − x]/b holds for all x > 0… Expand

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On rational bounds for the gamma function

- Zhen-Hang Yang, W. Qian, Yu-Ming Chu, W. Zhang
- Mathematics, Medicine
- Journal of inequalities and applications
- 8 September 2017

AbstractIn the article, we prove that the double inequality
x2+p0x+p0<Γ(x+1)<x2+9/5x+9/5$$ \frac{x^{2}+p_{0}}{x+p_{0}}< \Gamma(x+1)< \frac{x^{2}+9/5}{x+9/5} $$ holds for all x∈(0,1)$x\in(0, 1)$,… Expand

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On approximating the error function

- Zhen-Hang Yang, W. Qian, Y. Chu, E. Zhang
- Mathematics
- 2018

*Correspondence: chuyuming2005@126.com 1School of Mathematics and Computation Sciences, Hunan City University, Yiyang, 413000, China Full list of author information is available at the end of the… Expand

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Approximations for certain hyperbolic functions by partial sums of their Taylor series and completely monotonic functions related to gamma function

- Zhen-Hang Yang
- Mathematics
- 15 September 2016

Abstract In this paper, we establish some lower and upper bounds for certain hyperbolic functions in terms of partial sums of their Taylor series. These allow us to present two completely monotonic… Expand

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Monotonicity and sharp inequalities related to gamma function

- Zhen-Hang Yang, Jing-Feng Tian
- Mathematics
- 2018

In this paper, we investigate the monotonicity pattern of the function x → lnΓ(x+1) ln (x2 +a)− ln (x+a) on (0,1) for a 1 and resolve an open problem. From which we prove that the double inequality (… Expand

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