Provides a python module that implements the IFGF method as described in

Christoph Bauinger, Oscar P. Bruno, “Interpolated Factored Green Function” method for accelerated solution of scattering problems, Journal of Computational Physics, Volume 430, 2021

see https://www.sciencedirect.com/science/article/pii/S002199912030869X for details on the method.

Designed to be a plug-in replacement for the FastMultipole Method in bempp-cl

For optimal performance this library requires the fast hasmap implementation from https://github.com/martinus/unordered_dense