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Quarterly of Applied Mathematics

Quarterly of Applied Mathematics

Online ISSN 1552-4485; Print ISSN 0033-569X

   
 
 

 

Accurate approximations to the polygamma functions


Author: C. Stuart Kelley
Journal: Quart. Appl. Math. 37 (1979), 203-207
MSC: Primary 33A15
DOI: https://doi.org/10.1090/qam/542991
MathSciNet review: 542991
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Abstract: Empirically obtained approximations to the polygamma functions ${\psi ^{\left ( n \right )}}\left ( x \right )$ and their associated accuracies are presented. These simple functions are quite accurate, this accuracy increasing with $x$ and being best for small $n$. These approximate expressions are shown to be circuitously related to the Stirling approximation to the parent gamma function.


References [Enhancements On Off] (What's this?)

    J. J. Markham, Rev. Mod. Phys. 31, 956 (1959) T. H. Keil, Phys. Rev. A 140, 601 (1965) C. S. Kelley, Phys. Rev. B 6, 4112 (1972) Handbook of mathematical functions, ed. M. Abramowitz and I. A. Stegun, Natl. Bur. Std. (U.S.), Appl. Math. Ser. (U. S. Government Printing Office, Washington, D.C., 1964; Dover, New York, 1965); see especially chapter 6. C. S. Kelley, Phys. Rev. B 8, 1806 (1973) C. S. Kelley, J. Chem. Phys. 68, 1322 (1978)

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Article copyright: © Copyright 1979 American Mathematical Society