An Extension of the Euler–Maclaurin Summation Formula to Functions with Near Singularity

Abstract

SIAM Journal on Numerical Analysis, Volume 63, Issue 5, Page 2119-2132, October 2025.
Abstract. An extension of the Euler–Maclaurin (E–M) formula to near-singular functions is presented. This extension is derived based on earlier generalized E–M formulas for singular functions. The new E–M formulas consist of two components: a “singular” component that is a continuous extension of the earlier singular E–M formulas, and a “jump” component associated with the discontinuity of the integral with respect to a parameter that controls near singularity. The singular component of the new E–M formulas is an asymptotic series whose coefficients depend on the Hurwitz zeta function or the digamma function. Numerical examples of near-singular quadrature based on the extended E–M formula are presented, where accuracies of machine precision are achieved insensitive to the strength of the near singularity and with a very small number of quadrature nodes.