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In this paper, the logarithmically complete monotonicity property for a functions involving $q$-gamma function is investigated for $q\in(0,1).$ As applications of this results, some new inequalities for the $q$-gamma function are…

Classical Analysis and ODEs · Mathematics 2016-07-12 Khaled Mehrez

In this note we study the monotonicity of the function $x\mapsto \psi(1 +bx)^a/\psi(1 + ax)^b$. We also give the several inequalities involving the psi function, whic is the logarithmic derivative of the gamma function.

Classical Analysis and ODEs · Mathematics 2015-09-08 Barkat Ali Bhayo

In this short note we prove a conjecture for the interval $(0,1)$, related to a logarithmically completely monotonic function, presented in \cite{BG}. Then, we extend by proving a more generalized theorem. At the end we pose an open problem…

Classical Analysis and ODEs · Mathematics 2016-01-05 Valmir Krasniqi , Armend Sh. Shabani

In the article we present necessary and sufficient conditions for a function involving the logarithm of the gamma function to be completely monotonic and apply these results to bound the gamma function $\Gamma(x)$, the $n$-th harmonic…

Classical Analysis and ODEs · Mathematics 2014-12-02 Feng Qi

A class of functions involving the divided differences of the psi function and the polygamma functions and originating from Kershaw's double inequality are proved to be completely monotonic. As applications of these results, the…

Classical Analysis and ODEs · Mathematics 2011-05-13 Feng Qi , Bai-Ni Guo

In the paper the authors alternatively prove that the function $x^\alpha\big[\ln\frac{px}{x+p+1}-\psi_p(x)\big]$ is completely monotonic on $(0,\infty)$ if and only if $\alpha \le 1$, where $p\in\mathbb{N}$ and $\psi_p(x)$ is the…

Classical Analysis and ODEs · Mathematics 2014-08-13 Valmir Krasniqi , Feng Qi

This work has a purpose to collect selected facts about the completely monotone (CM) functions that can be found in books and papers devoted to different areas of mathematics. We opted for lesser known ones, and for those which may help…

Classical Analysis and ODEs · Mathematics 2015-06-19 Milan Merkle

Let $\psi(x)$ be the di-gamma function, the logarithmic derivative of the classical Euler's gamma function $\Gamma(x)$. In the paper, the author shows that the completely monotonic degree of the function $[\psi'(x)]^2+\psi''(x)$ is $4$,…

Classical Analysis and ODEs · Mathematics 2020-04-03 Feng Qi

In the paper, the authors establish integral representations of some functions related to the remainder of Burnside's formula for the gamma function and find the (logarithmically) complete monotonicity of these and related functions. These…

Classical Analysis and ODEs · Mathematics 2014-04-01 Feng Qi

We present some completely monotonic functions involving the $q$-gamma function that are inspired by their analogues involving the gamma function.

Classical Analysis and ODEs · Mathematics 2010-11-16 Peng Gao

In the paper the author provides necessary and sufficient conditions on $a$ for the function $\frac{1}{2}\ln(2\pi)-x+\bigl(x-\frac{1}{2}\bigr)\ln x-\ln\Gamma(x)+\frac1{12}{\psi'(x+a)}$ and its negative to be completely monotonic on…

Classical Analysis and ODEs · Mathematics 2016-08-02 Feng Qi

Let $ f:(0,\infty)\rightarrow \Bbb{R} $ be a completely monotonic function. In this paper, we present some properties of this functions and several new classes of completely monotonic functions. We also give some special functions such that…

Classical Analysis and ODEs · Mathematics 2025-05-30 Mostafa Najafi , Ali Morassaei

In this paper, we present some double inequalities involving certain ratios of the Gamma function. These results are further generalizations of several previous results. The approach is based on the monotonicity properties of some functions…

Classical Analysis and ODEs · Mathematics 2015-06-25 Kwara Nantomah

In the paper, the authors review origins, motivations, and generalizations of a series of inequalities involving several exponential functions and sums, establish three new inequalities involving finite exponential functions and sums by…

Classical Analysis and ODEs · Mathematics 2020-08-26 Feng Qi , Bai-Ni Guo

In the present paper, we give two new proofs for the necessary and sufficient condition $\alpha\le1$ such that the function $x^\alpha[\ln x-\psi(x)]$ is completely monotonic on $(0,\infty)$.

Classical Analysis and ODEs · Mathematics 2010-07-12 Feng Qi , Bai-Ni Guo

We introduce the notion of Dunkl completely monotonic functions on $\left(-\sigma,\sigma\right), \sigma>0$. We establish a restrictive version of the analogue of Schoenberg's theorem in Dunkl setting.

Classical Analysis and ODEs · Mathematics 2017-12-11 Jamel El Kamel , Khaled Mehrez

In this article we investigate the property of complete monotonicity within a special family $\mathcal{F}_s$ of functions in $s$ variables involving logarithms. The main result of this work provides a linear isomorphism between…

Classical Analysis and ODEs · Mathematics 2025-10-14 Rourou Ma , Julian Weigert

The psi function $\psi(x)$ is defined by $\psi(x)=\frac{\Gamma'(x)}{\Gamma(x)}$ and $\psi^{(i)}(x)$ for $i\in\mathbb{N}$ denote the polygamma functions, where $\Gamma(x)$ is the gamma function. In this paper we prove that a function…

Classical Analysis and ODEs · Mathematics 2013-07-04 Feng Qi , Bai-Ni Guo

We introduce completely monotonic functions of order $r>0$ and show that the remainders in asymptotic expansions of the logarithm of Barnes double gamma function and Euler's gamma function give rise to completely monotonic functions of any…

Classical Analysis and ODEs · Mathematics 2009-02-18 Stamatis Koumandos , Henrik L. Pedersen

In the present paper, we establish necessary and sufficient conditions for the functions $x^\alpha\bigl\lvert\psi^{(i)}(x+\beta)\bigr\lvert$ and $\alpha\bigl\lvert\psi^{(i)}(x+\beta)\bigr\lvert-x\bigl\lvert\psi^{(i+1)}(x+\beta)\bigr\lvert$…

Classical Analysis and ODEs · Mathematics 2010-07-12 Feng Qi , Senlin Guo , Bai-Ni Guo