What does sphert mean?

Answer 1

It is spherical harmonic transform library which will do the following.

TRANSFORMS A FIELD BETWEEN GRID AND SPECTRAL DOMAINS.

THIS VERSATILE ROUTINE WILL:

...TRANSFORM GRID TO SPECTRAL OR TRANSFORM SPECTRAL TO GRID;

...PASS A GAUSSIAN GRID OR AN EQUALLY-SPACE GRID;

...PASS A TRIANGULAR TRUNCATION OR A RHOMBOIDAL TRUNCATION;

...OPTIONALLY TRANSFORM WITH DERIVATIVES OF LEGENDRE FUNCTIONS;

...OPTIONALLY TRANSFORM FROM GRID DIVIDING BY COSLAT**2;

...OPTIONALLY MULTIPLY SPECTRAL FIELD BY COMPLEX FACTORS.