NBI: A library for Nystrom Boundary Integral calculations

Boundary integral methods are a popular approach to solving potential problems, in particular for the Laplace and Helmholtz problems in such areas as fluid dynamics, acoustics, and electromagnetism. They are a natural choice for the solution of problems in unbounded domains, such as wave scattering, where the radiation boundary condition is automatically satisfied by the nature of the formulation. The Nystrom method is one approach to the solution of boundary integral problems, which lends itself to acceleration using the Fast Multipole Method (FMM). NBI is a library for the solution of boundary integral problems based on the approach of Greengard et al. (2021) and the FMM methods of Gumerov & Duraiswami (Gumerov & Duraiswami, 2003, 2004, 2005, 2009). The code includes a number of executables which can be used to set up and solve problems on realistic geometries, with a number of examples provided for testing of the solver. Results can be visualized using GMSH (Geuzaine & Remacle, 2009), a standard free meshing program.