Bounds and monotonicity results for means involving the q-polygamma functions

Let ?q,n = (?1)n?1 ?(n)q for n ? N? {0} and q ? (0, 1), where ?(n) q is the q-polygamma functions. In this paper, by means of the monotonicity of means and two classes of completely monotonicity functions, we establish lower and upper bounds for the means I?q,n,w (a, b) defined, for b > a > 0 and w being positive and integrable on [a, b], by I?q,n,w (a, b) = ??1 q,n (?ba w(x)?q,n (x) dx/?ba w(x) dx); and prove that the sequence {I?q,n,w (a,b)} n?0 is decreasing with lim n?? I?q,n,w (a, b) = a. Moreover, we show that, for a, b ? R with a ? b, the function x 7? ??1 q,n (?ba w(t)?q,n (x + t) dt/?ba w(t) dt)?x is increasing from (?min {a, b} ,?) onto ( min {a, b}, ?2), where ?2 = logq (?ba w(t) qtdt/?ba w(t) dt). These generalize some known results.

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Publication Details

Journal
Filomat
Published
2025-01-01
DOI
https://doi.org/10.2298/fil2503051y
Primary Topic
Mathematical Inequalities and Applications
Type
article
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article

Bounds and monotonicity results for means involving the q-polygamma functions

Jing-Feng Tian, Zhen-Hang Yang
Filomat
Mathematical Inequalities and Applications
article

Bounds and monotonicity results for means involving the q-polygamma functions

Jing-Feng Tian, Zhen-Hang Yang
article en

Abstract

Let ?q,n = (?1)n?1 ?(n)q for n ? N? {0} and q ? (0, 1), where ?(n) q is the q-polygamma functions. In this paper, by means of the monotonicity of means and two classes of completely monotonicity functions, we establish lower and upper bounds for the means I?q,n,w (a, b) defined, for b > a > 0 and w being positive and integrable on [a, b], by I?q,n,w (a, b) = ??1 q,n (?ba w(x)?q,n (x) dx/?ba w(x) dx); and prove that the sequence {I?q,n,w (a,b)} n?0 is decreasing with lim n?? I?q,n,w (a, b) = a. Moreover, we show that, for a, b ? R with a ? b, the function x 7? ??1 q,n (?ba w(t)?q,n (x + t) dt/?ba w(t) dt)?x is increasing from (?min {a, b} ,?) onto ( min {a, b}, ?2), where ?2 = logq (?ba w(t) qtdt/?ba w(t) dt). These generalize some known results.

FilomatVol. 39(3)
North China Electric Power University (CN), Zhejiang Energy Research Institute (CN)
Openalex Percentile: Top 71%
Mathematical Inequalities and Applications
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Bounds and monotonicity results for means involving the q-polygamma functions — Jing-Feng Tian, Zhen-Hang Yang · Filomat (2025) | TGRS Research Map | TGRS