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Gamma Function

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lightbulbAbout this topic
The Gamma function is a mathematical function that extends the concept of factorial to complex and non-integer numbers. It is defined for positive real numbers as \( \Gamma(n) = (n-1)! \) and is represented by the integral \( \Gamma(z) = \int_0^{\infty} t^{z-1} e^{-t} dt \) for complex numbers with a positive real part.
lightbulbAbout this topic
The Gamma function is a mathematical function that extends the concept of factorial to complex and non-integer numbers. It is defined for positive real numbers as \( \Gamma(n) = (n-1)! \) and is represented by the integral \( \Gamma(z) = \int_0^{\infty} t^{z-1} e^{-t} dt \) for complex numbers with a positive real part.

Key research themes

1. How can the Gamma function be generalized and extended to unify special functions and address applications in fractional calculus and applied sciences?

Research on generalizing the Gamma function focuses on developing extended integral and series formulations with additional parameters or structures. These advances enable connections to fractional calculus operators, new special functions (e.g., k-gamma, generalized Mittag-Leffler), and wider classes of applications including stochastic models, diffraction, and physical processes. This theme is vital for enhancing the analytical toolkit provided by the Gamma function and for capturing more complex phenomena mathematically.

Key finding: The study proposes a novel generalized gamma function defined via infinite products involving powers of logarithms and connects this construction to generalized Euler-Mascheroni constants. It establishes essential properties... Read more
Key finding: This paper introduces the k-version of the Bessel function built on the k-gamma function, a generalization of the classical gamma. It demonstrates relationships between the k-Bessel function and other extended functions like... Read more

2. What are the properties and inequalities involving derivatives and expansions of generalized Gamma-related functions and their parameter dependencies?

Many investigations target the behavior of the Gamma function and its generalizations through asymptotic expansions, bounds, monotonicity, and derivatives with respect to parameters—especially in the context of special functions like digamma, trigamma, and the Whittaker functions. These studies develop inequalities, completely monotonic properties, and analytic expansions that inform approximation, numerical evaluation, and theoretical insights critical to mathematical analysis and applied problems.

Key finding: The authors derive a detailed asymptotic expansion for a class of generalized gamma functions Γ_μ(v) involving parameter μ. They rigorously demonstrate the function's completely monotonic properties with respect to its... Read more
Key finding: Extending classical inequalities for the Gamma and digamma functions, this paper proves that the trigamma function ψ'(z) exhibits geometric convexity (GG-convexity) and GA-convexity on (0, ∞). Among its main results is that... Read more
Key finding: This paper systematically derives parameter derivatives of the Whittaker M function via confluent hypergeometric function expansions. The differentiation leads to infinite series involving quotients of digamma and gamma... Read more
Key finding: Extending the previous work on Whittaker parameter derivatives, this study analyzes the W variant of Whittaker functions with respect to κ and μ parameters. It develops infinite series and integral analytic formulae,... Read more

3. How do the Gamma function and its variants inform probability distributions, statistical modeling, and applications in data analysis?

The Gamma function underpins numerous continuous probability distributions, including gamma, beta, chi-square, F, Student’s t, and various logistic distributions. Research in this theme develops new modified or generalized Gamma-based models and investigates their probabilistic properties, parameter estimation methods, and applications to real-world data such as medical statistics, reliability, and environmental processes. This theme highlights the Gamma function’s foundational role in statistical theory and applied data analysis.

Key finding: The authors propose a modified Gamma (MG) distribution introducing a risk intensity control to modulate the right tail behavior for data exhibiting light tails relative to classical gamma. They derive analytical properties of... Read more
Key finding: This paper unifies and extends type I and II generalized logistic distributions by introducing the gamma generalized logistic distribution (GGLD) with three parameters, capturing skewness and kurtosis flexibility. The authors... Read more
Key finding: This paper reviews the derivation of several fundamental continuous probability distributions—including gamma, beta, chi-square, Student’s t, and F distributions—directly via the Euler Gamma function. The expository work... Read more

All papers in Gamma Function

In this research Riemann hypothesis is investigated for a proof. A functional extension of the Riemann zeta function is proposed for which non trivial zeroes can be generated. It found that non trivial zeroes can also be generated outside... more
We prove a remarkable formula of Ramanujan for the logarithmic derivative of the gamma function, which converges more rapidly than classical expansions, and which is stated without proof in the notebooks . The formula has a number of very... more
This study demonstrated that the Standardised Flow Index (SFI) was a simple and useful tool to research, monitor and manage hydrologic drought in a highly regulated river system, the Murrumbidgee River in southeast Australia. To validate... more
In 1859 Riemann defined the zeta function () s . From Gamma function he derived the zeta function with Gamma function () s . () s  and () s  are the two different functions. It is false that () s  replaces () s . After him later... more
We examined two subjectively distinct memory states that are elicited during recognition memory in humans and compared them in terms of the gamma oscillations (20-60 Hz) in the electroencepahalogram (EEG) that they induced. These... more
Background: Electron mode is used for treatment of superficial tumours in linac-based radiotherapy.
A 363 (2007) 213] and [M.S.H. Chowdhury, I. Hashim, Phys. Lett. A 372 (2008) 1240] is exactly solvable, analyses the equation fully and, furthermore, gives analytic exact solution in implicit form for each value of parameters of equation.
We prove several isoperimetric inequalities for the conformal radius (or equivalently for the Poincaré density) of polygons on the hyperbolic plane. Our results include, as limit cases, the isoperimetric inequality for the conformal... more
The aim of this paper is to introduce an approximations family of the factorial function that contains Stirling's formula, Burnside's formula and Gosper's formula. The parameters which provide the best approximations are indicated.... more
In this research Riemann hypothesis is investigated for a proof. A functional extension of the Riemann zeta function is proposed for which non trivial zeroes can be generated. It found that non trivial zeroes can also be generated outside... more
Wallis's method of interpolation attracted the attention of the young Euler, who obtained some important results. The problem of interpolation led Euler to formulate the problem of integration, i.e., to express the general term of a... more
In this article, we study lower and upper triangular factorizations of the complex Wishart matrix. Further, using these factorizations, we obtain several expected values of scalar and matrix valued functions of the complex Wishart matrix.... more
The batch flotation process has been commonly characterized assuming a flotation rate distribution function F(k), e.g.: Dirac delta, Rectangular, Gamma or Weibull functions. The identification of F(k) for the collection zone of continuous... more
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 improve some known results for bounding the gamma function.
The frequency-length distribution of the San Andreas fault system was analyzed and compared with theoretical distributions. Both.density and cumulative distributions were calculated, and errors were estimated. Neither exponential... more
The batch flotation process has been commonly characterized assuming a flotation rate distribution function F(k), e.g.: Dirac delta, Rectangular, Gamma or Weibull functions. The identification of F(k) for the collection zone of continuous... more
In this paper we analyze the different generating eta − and zeta functions, which in return produce the ME numbers that are directly linked to the Bernoulli −. We establish the characteristics of these numbers, their computation, their... more
In this paper we establish an identity that relates Pochhammer symbol and the ratio of gamma functions. The identity is derived using the Mellin series representation for the solution of a general algebraic equation.
Disdrometer data measured during the passage of tropical continental squall lines in Darwin, Australia, are analyzed to study characteristics of raindrop size distribution (DSD). Fifteen continental squall lines were selected for the DSD... more
Models used to predict digestibility and fill of the dietary insoluble fibre (NDF) treat the ruminoreticular particulate mass as a single pool. The underlying assumption is that escape of particles follows firstorder kinetics. In this... more
Many authors introduced and studied positive linear operators, using Euler's gamma function Γp, p > 0. We shall define a more general linear transform Γ (a,b) p , a, b ∈ R, from which we obtain as particular cases the gamma first-kind... more
We deal here with a class of integral transformations with respect to parameters of hypergeometric functions or the index transforms. In particular, we treat the familiar Olevskii transform, which is associated with the Gauss... more
From the characterisation of geometrically convex and geometrically concave functions defined on (0, A] or [A, ∞) with A > 0, by means of their multiplicative conditions, we obtain unified proofs of some known and new inequalities.... more
We discuss q-analogues of the Euler reflection formula and the Euler gamma integral. The central role here is played by the Ramanujan q-extension of the Euler integral representation for the gamma function, which allows deriving the... more
This paper considers various integrals where the integrand includes the log gamma function (or its derivative, the digamma function) multiplied by a trigonometric or hyperbolic function. Some apparently new integrals and series are... more
In this paper, we introduce a function , ; ( , , ) z s a     , which is an extension to the general Hurwitz-Lerch Zeta function. Having defined the incomplete generalized beta type-2 and incomplete generalized gamma functions, some... more
Formal expansions, giving as particular cases semiasymptotic expansions, of the ratio of two gamma functions are obtained.
We prove monotonicity results and asymptotic inequalities for the function r( x + h)/T( x + 1) with the usual notation for the gamma function.
conjectured that the function log Γ(x+1)
From the integration of non-symmetrical hyperboles, a one-parameter generalization of the logarithmic function is obtained. Inverting this function, one obtains the generalized exponential function. We show that functions characterizing... more
On the one hand the Fermi-Dirac and Bose-Einstein functions have been extended in such a way that they are closely related to the Riemann and other zeta functions. On the other hand the Fourier transform representation of the gamma and... more
This paper describes an accurate method to obtain the Tone Reproduction Curve (TRC) of display devices without using a measurement device. It is an improvement of an existing technique based on human observation, solving its problem of... more
A Rodrigues-type representation for the second kind solutions of a second-order di erential equation of hypergeometric type is given. This representation contains some integrals related with relevant special functions. For these... more
In this article we study a generalisation of Lalescu's sequence involving the Gamma function. n √ n!. The sequence (Ln)n∈N , also known as Lalescu's sequence, has been studied by many Romanian mathematicians and it has been shown... more
This paper continues the work by Molchan ( , 1991b, who has considered earthquake prediction as a problem of the optimization of a certain loss function -y. FUnction -y is defined by specific social, economic, and geophysical goals. This... more
There is a large body of evidence that stress-induced DNA damage may be responsible for cell lethality, cancer proneness and/or immune reaction. However, statistical features of their repair rate remain poorly documented. In order to... more
The shape of the lactation curve for 475 Turkish Holsteins was estimated by fitting a gamma function to daily milk yields from monthly recording of 754 lactations. Lactation curve traits that were analyzed included a scaling factor... more
This study compared fullframe fisheye photography and cover photography with destructive leaf area index (L) estimation and the Licor LAI-2000 plant canopy analyser (PCA) in plantations of the vertical leaved species Eucalyptus globulus.... more
In this paper, some complete monotonicity, strongly complete monotonicity and logarithmically complete monotonicity of functions related to the gamma and psi functions are obtained.
Let s and z be complex variables, (s) the Gamma function, and (s) ν = (s+ν) (s) for any complex ν the generalized Pochhammer symbol. The principal aim of the paper is to investigate the function
The aim of this paper is to improve the Ramanujan formula for approximation the gamma function. A fast asymptotic series is constructed.
In this paper, we continue to study properties of rational approximations to Euler's constant and values of the Gamma function defined by linear recurrences, which were found recently by A. I. Aptekarev and T. Rivoal. Using multiple... more
We performed a comparison between two source signal extraction algorithms, namely the Wavelet Denoising (WD) by Soft Thresholding and Independent Component Analysis (ICA) on a simulated functional optical imaging data. The simulated data... more
We introduce the Stirling's formula in a more general class of approximation formulas to extend the integral representation of Z. Liu [Tamsui Oxf. J. Math. Sci. 4 (2007) 389-392]. Finally, an accurate approximation for the factorial... more
The aim of this paper is to re…ne some recent results stated by Alzer and Grinshpan [Inequalities for the gamma and q-gamma functions J. Approx. Theory 144 67 -83] and Batir [An interesting double inequality for Euler's gamma function J.... more
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