• Title/Summary/Keyword: psi (or digamma) function

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INFINITE SERIES ASSOCIATED WITH PSI AND ZETA FUNCTIONS

  • KIM, YONGSUP
    • Honam Mathematical Journal
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    • v.22 no.1
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    • pp.53-60
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    • 2000
  • We evaluate some interesting families of infinite series expressed in terms of the Psi (or Digamma) and Zeta functions by analyzing the well-known identity associated with $_3F_2$ due to Watson. Some special cases are also considered.

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CERTAIN CLASSES OF INFINITE SERIES DEDUCIBLE FROM MELLIN-BARNES TYPE OF CONTOUR INTEGRALS

  • Choi, Junesang;Agarwal, Praveen
    • The Pure and Applied Mathematics
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    • v.20 no.4
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    • pp.233-242
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    • 2013
  • Certain interesting single (or double) infinite series associated with hypergeometric functions have been expressed in terms of Psi (or Digamma) function ${\psi}(z)$, for example, see Nishimoto and Srivastava [8], Srivastava and Nishimoto [13], Saxena [10], and Chen and Srivastava [5], and so on. In this sequel, with a view to unifying and extending those earlier results, we first establish two relations which some double infinite series involving hypergeometric functions are expressed in a single infinite series involving ${\psi}(z)$. With the help of those series relations we derived, we next present two functional relations which some double infinite series involving $\bar{H}$-functions, which are defined by a generalized Mellin-Barnes type of contour integral, are expressed in a single infinite series involving ${\psi}(z)$. The results obtained here are of general character and only two of their special cases, among numerous ones, are pointed out to reduce to some known results.

APPLICATION OF A CERTAIN FAMILY OF HYPERGEOMETRIC SUMMATION FORMULAS ASSOCIATED WITH PSI AND ZETA FUNCTIONS

  • Choi, June-Sang;H.M.Srivastava;Kim, Yong-Sup
    • Communications of the Korean Mathematical Society
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    • v.16 no.2
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    • pp.319-332
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    • 2001
  • The main object of this paper is first to give tow contiguous analogues of a well-known hypergeometric summation formula for $_2$F$_1$(1/2). We then apply each of these analogues with a view to evaluating the sums of several classes of series in terms of Psi(or Digamma) and the Zeta functions. Relevant connections of the series identities presented here with those given elsewhere are also pointed out.

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A DEFINITE INTEGRAL FORMULA

  • Choi, Junesang
    • East Asian mathematical journal
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    • v.29 no.5
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    • pp.545-550
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    • 2013
  • A remarkably large number of integral formulas have been investigated and developed. Certain large number of integral formulas are expressed as derivatives of some known functions. Here we choose to recall such a formula to present explicit expressions in terms of Gamma function, Psi function and Polygamma functions. Some simple interesting special cases of our main formulas are also considered. It is also pointed out that the same argument can establish explicit integral formulas for other those expressed in terms of derivatives of some known functions.

LOG-SINE AND LOG-COSINE INTEGRALS

  • Choi, Junesang
    • Honam Mathematical Journal
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    • v.35 no.2
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    • pp.137-146
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    • 2013
  • Motivated essentially by their potential for applications in a wide range of mathematical and physical problems, the log-sine and log-cosine integrals have been evaluated, in the existing literature on the subject, in many different ways. The main object of this paper is to present explicit evaluations of some families of log-sine and log-cosine integrals by making use of the familiar Beta function.

CERTAIN FORMULAS INVOLVING EULERIAN NUMBERS

  • Choi, Junesang
    • Honam Mathematical Journal
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    • v.35 no.3
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    • pp.373-379
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    • 2013
  • In contrast with numerous identities involving the binomial coefficients and the Stirling numbers of the first and second kinds, a few identities involving the Eulerian numbers have been known. The objective of this note is to present certain interesting and (presumably) new identities involving the Eulerian numbers by mainly making use of Worpitzky's identity.

NOTE ON STIRLING POLYNOMIALS

  • Choi, Junesang
    • Journal of the Chungcheong Mathematical Society
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    • v.26 no.3
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    • pp.591-599
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    • 2013
  • A large number of sequences of polynomials and numbers have arisen in mathematics. Some of them, for example, Bernoulli polynomials and numbers, have been investigated deeply and widely. Here we aim at presenting certain interesting and (potentially) useful identities involving mainly in the second-order Eulerian numbers and Stirling polynomials, which seem to have not been given so much attention.

SERIES REPRESENTATIONS FOR THE EULER-MASCHERONI CONSTANT $\gamma$

  • Choi, June-Sang;Seo, Tae-Young
    • East Asian mathematical journal
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    • v.18 no.1
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    • pp.75-84
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    • 2002
  • The third important Euler-Mascheroni constant $\gamma$, like $\pi$ and e, is involved in representations, evaluations, and purely relationships among other mathematical constants and functions, in various ways. The main object of this note is to summarize some known series representaions for $\gamma$ with comments for their proofs, and to point out that one of those series representaions for $\gamma$ seems to be incorrectly recorded. A brief historical comment for $\gamma$ is also provided.

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INEQUALITIES AND COMPLETE MONOTONICITY FOR THE GAMMA AND RELATED FUNCTIONS

  • Chen, Chao-Ping;Choi, Junesang
    • Communications of the Korean Mathematical Society
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    • v.34 no.4
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    • pp.1261-1278
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    • 2019
  • It is well-known that if ${\phi}^{{\prime}{\prime}}$ > 0 for all x, ${\phi}(0)=0$, and ${\phi}/x$ is interpreted as ${\phi}^{\prime}(0)$ for x = 0, then ${\phi}/x$ increases for all x. This has been extended in [Complete monotonicity and logarithmically complete monotonicity properties for the gamma and psi functions, J. Math. Anal. Appl. 336 (2007), 812-822]. In this paper, we extend the above result to the very general cases, and then use it to prove some (logarithmically) completely monotonic functions related to the gamma function. We also establish some inequalities for the gamma function and generalize some known results.