29 citations · 75 across the 5 of their papers we have counts for
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math.CA2010★ 16 cited
A completely monotonic function involving the tri- and tetra-gamma functions
Feng Qi, Bai-Ni Guo
The psi function is defined by and for denote the polygamma functions, where is the gamma function. In this pa…
math.CA2010★ 22 cited
A refinement of a double inequality for the gamma function
Feng Qi, Bai-Ni Guo
In the paper, we present a monotonicity result of a function involving the gamma function and the logarithmic function, refine a double inequality for the gamma function, and impro…
math.CA2009★ 29 cited
Sharp inequalities for polygamma functions
Feng Qi, Bai-Ni Guo
The main aim of this paper is to prove that the double inequality \frac{(k-1)!}{\Bigl\{x+\Bigl[\frac{(k-1)!}{|ψ^{(k)}(1)|}\Bigr]^{1/k}\Bigr\}^k} +\frac{k!}{x^{k+1}}<\bigl|ψ^{(k)}(x…
math.CA2009★ 4 cited
Logarithmic convexity of Gini means
Feng Qi, Bai-Ni Guo
In the paper, the monotonicity and logarithmic convexity of Gini means and related functions are investigated.