WDigamma WPolygamma WTrigamma

WPolygamma() Function WPolygamma ( X As  Double, N As  Long  ) Polygamma function ψn(x) (derivative of psi function ψ(x)) Purpose WPolygamma computes the polygamma function ψn(x), where x is not 0, -1, -2, ... ψn(x) = dnψ(x)/dxn = d(n+1)/dx(n+1) ln(Γ(x)) Returns Polygamma function ψn(x). Parameters [in] X Argument x. (X <> 0 and X <> an negative integer) [in] N Argument n. (N >= 0) Reference boost/math/special_functions