Finite-Part Integration of the Hilbert Transform

Abstract

The one-sided and full Hilbert transforms are evaluated exactly by means of the method of finite-part integration [E.A. Galapon, \textit{Proc. Roy. Soc. A} \textbf{473}, 20160567 (2017)]. In general, the result consists of two terms -- the first is an infinite series of finite-part of divergent integrals, and the second is a contribution arising from the singularity of the kernel of transformation. The first term is precisely the result obtained when the kernel of transformation is binomially expanded in positive powers of the parameter of transformation, followed by term-by-term integration, and the resulting divergent integrals assigned values equal to their finite-parts. In all cases, the finite-part contribution is present while the presence or absence of the singular contribution depends on the interval of integration and on the parity of the function under transformation about the origin. From the exact evaluation of the Hilbert transform, the dominant asymptotic behavior for arbitrarily small parameter is obtained.