S2LET: Fast wavelets on the sphere
S2LET provides efficient routines for fast wavelet analysis of signals on the sphere. It supports both axisymmetric and directional wavelet transforms. The wavelet transforms are theoretically exact, i.e. the original signal can be synthesised from its wavelet coefficients exactly since the wavelet coefficients capture all the information content of band-limited signals.
It is primarily intended to work with the SSHT code built on our novel sampling theorem on the sphere to perform exact spherical harmonic transforms on the sphere. Directional wavelet transforms rely on the SO3 code built on our novel sampling theorem on the rotation group. S2LET also supports the HEALPIX sampling scheme, in which case spherical harmonic transforms are not theoretically exact but can be made to achieve reasonable numerical accuracy.