In benchmarking pnbd.LL
runs more quickly and
it returns the same results if it uses this helper instead of
hypergeo
, which is the default. But h2f1
is such a barebones function that in some edge cases it will keep
going until you get a segfault, where hypergeo
would have failed with a proper error message.
h2f1(a, b, c, z)
counterpart to A in hypergeo
counterpart to B in hypergeo
counterpart to C in hypergeo
counterpart to z in hypergeo
Fader, Peter S., and Bruce G.S. Hardie. "A Note on Deriving the Pareto/NBD Model and Related Expressions." November. 2005. Web. http://www.brucehardie.com/notes/008/