A superadditive property of Hadamard’s gamma function
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Abstract
Hadamard’s gamma function is defined by where Γ denotes the classical gamma function of Euler. H is an entire function, which satisfies H(n)=(n−1)! for all positive integers n. We prove the following superadditive property.
$$H(x)=\frac{1}{\Gamma(1-x)}\frac{d}{dx}\log \frac{\Gamma(1/2-x/2)}{\Gamma(1-x/2)},$$
Let α be a real number. The inequality holds for all real numbers x,y with x,y≥α if and only if α≥α0=1.5031…. Here, α0 is the only solution of H(2t)=2H(t) in [1.5,∞).
$$H(x)+H(y)\leq H(x+y)$$
Keywords
Hadamard’s and Euler’s gamma functions Psi function Superadditive Convex InequalitiesMathematics Subject Classification (2000)
33B15 39B62Preview
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