Compute generalised second order Stirling numbers
Compute generalised second order Stirling numbers via libstb.
libstb “contains library routines that provide alternative ways of computing generalised second order Stirling numbers used in working with Pitman-Yor and Dirichlet processes (PYP and DP).” libstb is written by Wray Buntine.
An instance of the class STable provides access to (pre-calculated) generalized Stirling numbers of the second kind, \(S^n_{m,a}\). Initialize the table with the maximum n and maximum m which will be needed.
>>> import pystb
>>> stable = pystb.STable(10000, 10000, 0.5)
>>> stable.S(5, 3) # S^5_{3, 0.5}
>>> stable[5, 3] # alias for stable.S(5, 3)
