For more information, please see the following technical note On the Computation of the Logarithm of the Modified Bessel Function of the Second Kind pdf. if you use this implementation, please cite: ...
Relative error of complex-bessel (Rust), AMOS/TOMS 644 (Fortran), and SciPy (Python) versus mpmath 50+ digit reference values, across all Bessel and Airy functions ...