The Spectral Toolkit is a C++ spectral transform library written by Rodney James and Chuck Panaccione while at the National Center for Atmospheric Research between 2002 and 2005. The library contains a functional subset of FFTPACK and SPHEREPACK, including real and complex FFTs in 1-3 dimensions, and a spherical harmonic transform. Multithreading is supported through POSIX threads for the multidimensional transforms. This reference guide provides details of the public interface as well as the internal implementation of the library.
