Monotonicity Results For The Gamma Function
@article{Chen2002MonotonicityRF, title={Monotonicity Results For The Gamma Function}, author={Chao Chen and Feng Qi (祁锋)}, journal={Journal of Inequalities in Pure \& Applied Mathematics}, year={2002}, volume={4} }
The function 1/x x+1 is strictly decreasing on[1,∞), the function [Γ(x+1)]1/x √ x is strictly increasing on[2,∞), and the function 1/x √ x+1 is strictly increasing on[1,∞), respectively. From these, some inequalities, for example, the Minc-Sathre inequality, are deduced, and two open problems posed by the second author are solved partially.
41 Citations
MONOTONICITY AND CONVEXITY OF THE FUNCTION
- Mathematics
- 2004
For α > 0 a real number, the function x √ Γ(x+1) x+α √ Γ(x+α+1) is increasing with x ∈ (x0,∞) and logarithmically concave with x ∈ [1,∞), where x0 ∈ (0, 1) is a constant. Moreover, some monotonicity…
Complete Monotonicities of Functions Involving the Gamma and Digamma Functions
- Mathematics
- 2004
In the article, the completely monotonic results of the functions [Γ(x+ 1)]1/x, [Γ(x+α+1)]1/(x+α) [Γ(x+1)]1/x , [Γ(x+1)]1/x (x+1)α and [Γ(x+1)]1/x xα in x ∈ (−1,∞) for α ∈ R are obtained. In the…
A monotonicity property of the -function.
- Mathematics
- 2002
It is shown that the function x 7→ 1 + 1 x ln Γ(x+ 1)− ln(x+ 1) is strictly completely monotone on (−1,∞) and tends to one as x→ −1, to zero as x→∞. This property is derived from a suitable integral…
Monotonicity Results and Inequalities for the Gamma and Incomplete Gamma Functions
- Mathematics
- 2002
In the article, using the monotonicity and inequalities of the generalized weighted mean values with two parameters, we prove that the functions [ Γ(s)/Γ(r) ]1/(s−r) , [ Γ(s, x)/Γ(r, x) ]1/(s−r) and…
A Complete Monotonicity of the Gamma Function
- Mathematics
- 2004
The function 1 x ln Γ(x+1)−lnx+1 is strictly completely monotonic on (0,∞). The classical gamma function is usually defined for Re z > 0 by
Monotonicity of sequences involving geometric means of positive sequences with monotonicity and logarithmical convexity
- Mathematics
- 2006
Let f be a positive function such that x [ f (x + 1)/f (x)− 1 ] is increasing on [1,∞) , then the sequence { n √∏n i=1 f (i) / f (n + 1) }∞ n=1 is decreasing. If f is a logarithmically concave and…
SOME LOGARITHMICALLY COMPLETELY MONOTONIC FUNCTIONS RELATED TO THE GAMMA FUNCTION
- Mathematics
- 2010
In this article, the logarithmically complete monotonicity of some functions such as 1 for fi 2 R on (i1;1) or (0;1) are obtained, some known results are recovered, extended and generalized.…
References
SHOWING 1-10 OF 37 REFERENCES
Monotonicity Results and Inequalities for the Gamma and Incomplete Gamma Functions
- Mathematics
- 2002
In the article, using the monotonicity and inequalities of the generalized weighted mean values with two parameters, we prove that the functions [ Γ(s)/Γ(r) ]1/(s−r) , [ Γ(s, x)/Γ(r, x) ]1/(s−r) and…
Monotonicity of Sequences Involving Convex and Concave Functions
- Philosophy
- 2003
Let f be an increasing and convex (concave) function on [0, 1) and φ a positive increasing concave function on [0,∞) such that φ(0) = 0 and the sequence { φ(i+1) ( φ(i+1) φ(i) − 1 )} i∈N decreases (…
Some Inequalities involving ( r !) 1/ r
- Mathematics
- 1964
In a recent investigation of a conjecture on an upper bound for permanents of (0, 1)-matrices ( 2 ) we obtained some inequalities involving the function ( r !) 1/ r which are of interest in…
The best bounds in Gautschi's inequality
- Mathematics
- 2000
Different approach to both Gautschi’s inequalities (1) and (2) is given. This results in obtaining the best upper bound in (1) and the best lower bound in (2). The main result is the proof of the…
Some Inequalities of the Incomplete Gamma and Related Functions
- Mathematics
- 1999
In the article, many inequalities of the integrals f 00 z e'dt, e"dt, j for p > 0, which are related to the incomplete gamma function, are established. The approach used in the paper could yield more…
On a Generalization of Martins’ Inequality
- Mathematics
- 2003
Abstract. Let be an increasing nonconstant sequence of positive real numbers. Under certain conditions on this sequence we prove the following inequality
where n,m ∈ ℕ and r is a positive number, an!…
An Inequality for the Ratios of the Arithmetic Means of Functions with a Positive Parameter
- Mathematics
- 2001
In the article, an integral inequality for the ratios of the arithmetic means of functions with a positive parameter are obtained, and an open problem, posed by B.-N. Guo and F. Qi in “An algebraic…
The Extended Mean Values: Definition, Properties, Monotonicities, Comparison, Convexities, Generalizations, and Applications
- Mathematics
- 2001
The extended mean values E(r, s; x, y) play an important role in theory of mean values and theory of inequalities, and even in the whole mathematics, since many norms in mathematics are always means.…
Inequalities and monotonicity of the ratio of the geometric means of a positive arithmetic sequence with unit difference
- Mathematics
- 2003
For any nonnegative integer k and natural numbers n and m, the following inequalities are obtained on the ratio for the geometric means of a positive arithmetic sequence with unit difference: where α…
INEQUALITIES AND MONOTONICITY FOR THE RATIO OF GAMMA FUNCTIONS
- Mathematics
- 2003
In this article, using Stirling’s formula, the series-expansion of digamma functions and other techniques, some inequalities and monotonicity concerning the ratio of gamma functions are obtained,…