BESSELJ is a Python library which evaluates Bessel J functions of noninteger order.
At the moment, this library simply consists of a test case for the scipy.special.jv(nu,x) function. Later, the source code for some other implementations of the Bessel J function may be added.
The computer code and data files made available on this web page are distributed under the GNU LGPL license.
BESSELJ is available in a C version and a C++ version and a FORTRAN90 version and a MATLAB version and a Python version.
POLPAK, a Python library which evaluates certain mathematical functions, especially some recursive polynomial families.
You can go up one level to the Python source codes.