Hankel function integration

1

Hi everyone, the zero order Hankel function of second kind H(|r-r’|) is singular when r=r’ in the 2d space. I want to assemble the boundary integration with Hankel function. It may meet the singular point. Does dolfin have any method to overcome it? If not, there is analytic expression for the boundary element integration, like this:

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How to use it in fenics? Thank you in advance

2

Indeed my question is that I have a domain for which the trial function is expanded with node base functions. Also there is a surface integration equation which should be expanded using pulse functions with unknowns defined at the element edge center on the exterior boundary, that equals to the average of the node unknowns at the edge ends. Then how do I formulate it in fenics?