This is the library ScaFaCoS ("Scalable Fast Coulomb Solver").

ScaFaCoS is a parallel library for solving the Coulomb problem. It
provides various state-of-the-art methods with a common interface.

Further details on the project, downloads, online documentation 
as well as support contact data are given on the projct's web page

  www.scafacos.de

After invoking 'make doc', the User's Guide of the ScaFaCoS 
library is found in the file 

  doc/manual.pdf