These are probably not super useful for most users. They should all be equivalent to the scipy bessel functions. However, in C++ we wanted to avoid dependencies that would have given us these Bessel functions, so we implemented our own. The Python interface is mostly to enable unit tests that these C++ function are correct.
.. autofunction:: galsim.bessel.j0
.. autofunction:: galsim.bessel.j1
.. autofunction:: galsim.bessel.jv
.. autofunction:: galsim.bessel.jn
.. autofunction:: galsim.bessel.kv
.. autofunction:: galsim.bessel.kn
.. autofunction:: galsim.bessel.yv
.. autofunction:: galsim.bessel.yn
.. autofunction:: galsim.bessel.iv
.. autofunction:: galsim.bessel.j0_root
.. autofunction:: galsim.bessel.jv_root