Faster inverse gamma and factorial for the WP 34S

[Bit]

(02-07-2015 07:34 PM)Dieter Wrote:  The standard lib that comes with the 34s firmware contains a digamma routine - so why not use the obvious and setup a simple Newton solver for Γ^-1(a):

x := x + (a/Γ(x) – 1) / Ψ(x)

That's a good idea, thank you. When I have the time, I'll see if this method is any faster if used with the built-in digamma routine (which is a compile time option, not available by default).