Sharpness of Muqattash-Yahdi problem

Abstract

Abstract. Let ψ denote the psi (or digamma) function. We determine the values of the parameters p, q and r such thatis 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.