Introduce logk_gen (Y = ln X where X ~ K) with analytically derived
mean/variance via the CGF, numerically stable logpdf using an asymptotic
Bessel expansion for large arguments, CDF delegation to k_dist, and a
compound-gamma rvs sampler.
Add _rvs to k_dist via the same compound-gamma algorithm and extend
TestKDistPdf with stats and rvs coverage. Add a full TestLogK suite
covering pdf normalization, change-of-variable identity, CDF consistency,
analytical moment checks, and rvs moment checks.
Module-level docstring added to distributions.py
neutonsevero
c59bc55fe5