fsph is a library to efficiently compute series of spherical harmonics (i.e. all of Ylm for a set of l).
It is based on math enumerated by Martin J. Mohlenkamp at https://www.ohiouniversityfaculty.com/mohlenka/research/uguide.pdf.
fsph uses portions of the cuda_complex project, located at https://github.com/jtravs/cuda_complex.git . Its code and license are located in the cuda_complex subdirectory.