This might actually be Differential Geometry but I'll post it here for now.

I was looking at a paper yesterday about quantization conditions when working on a manifold based on the surface of a sphere. I've never seen that before and it's apparently a lot less intuitive than I would have thought. The paper mentions a "generalized Fourier transform." The best I could do on an internet search is

here. But I don't think that's what the paper had in mind because the Wolfram link looks like it's modeled in the usual 3-space, not a more generalized manifold.

Has anyone heard of this? I can quote some sections of the paper if you need it.

Thanks!

-Dan