Singular integral - Wikipedia
en.wikipedia.org › wiki › Singular_integralIn mathematics, singular integrals are central to harmonic analysis and are intimately connected with the study of partial differential equations. Broadly speaking a singular integral is an integral operator () = (,) (), whose kernel function K : R n ×R n → R is singular along the diagonal x = y. Specifically, the singularity is such that |K(x, y)| is of size |x − y| −n asymptotically as |x − y| → 0.