This repo contains a basic Fortran and Matlab wrapper for running the 8th order box code by Greengard and Ethridge.
To verify successful compilation of the library, run make test
after copying over the appropriate version of make.inc
To generate the mex file run make matlab after copying over the
appropriate version of make.inc
The interface on input requires a level restricted adaptive tree, and function values tabulated on a 8th order tensor product chebyshev grid at all the leaf boxes.
For more detailed documentation for the input format of the level
restricted tree checkout either the subroutine lbfmm2d in src/lbfmm2d.f
or the matlab file volfmm8.m or volfmm8_legacy.m
There are two matlab interfaces, one for the legacy tree format, and one for the new tree format
In fortran on a single core, the code runs at approximately 500 k points per second per core for 12 digits of accuracy.
The legacy version of the fortran code, poisson8.f contains more complicated options for evalauting the volume potential such as imposing periodic boundary conditions, or imposing dirichlet/neumann boundary conditions on the edge of the square. However, the more complicated routines have not been thoroughly tested in this wrapped environment and should be used with caution.