  The spherical harmonic transform is a powerful tool in the analysis of
spherical data sets, such as the cosmic microwave background data. In this
work, we present a new scheme for the spherical harmonic transforms that
supports both CPU and GPU computations, which is specially efficient on a large
number of sky maps. By comparing our implementation with the standard
Libsharp-HEALPix program, we demonstrate 2-10 times speedup for the CPU
implementation, and up to 30 times speedup when a state-of-the-art GPU is
employed. This new scheme's software package is available via an open source
GitHub repository.
