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Computational & Applied Mathematics

On-line version ISSN 1807-0302


CHEN, Chao-Ping  and  MORTICI, Cristinel. Sharpness of Muqattash-Yahdi problem. Comput. Appl. Math. [online]. 2012, vol.31, n.1, pp.85-93. ISSN 1807-0302.

Let ψ denote the psi (or digamma) function. We determine the values of theparameters p, q and r such that ψ(n) ≈ ln(n + p) - is the best approximations. Also, we present closer bounds for psi function, which sharpens some known results due to Muqattash and Yahdi, Qi and Guo, and Mortici. Mathematical subject classification: 33B15, 26D15.

Keywords : psi function; polygamma functions; rate of convergence; approximations.

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