WDigamma WPolygamma WTrigamma

WTrigamma() Function WTrigamma ( X As  Double ) Trigamma function ψ1(x) Purpose This function computes the trigamma function ψ1(x), where x is not 0, -1, -2, ... ψ1(x) = dψ(x)/dx = d2/dx2 ln(Γ(x)) Returns Trigamma function ψ1(x). Parameters [in] X Argument x. (X <> 0 and X <> an negative integer) Reference boost/math/special_functions