cdigamma cdigamma_sub digamma polygamma trigamma

cdigamma() doublecomplex cdigamma ( doublecomplex  z ) Digamma (or psi) function ψ(z) (complex argument) Purpose cdigamma computes the digamma (or psi) function at a complex number z, where z is not 0, -1, -2, ... ψ(z) = d/dz ln(Γ(z)) = Γ'(z)/Γ(z) Returns Digamma (or psi) function ψ(z). Parameters [in] z Argument z. (z != negative integer, z != 0) Error handling If z is zero or real negative integer, NaN + NaN*I is returned and domain error (EDOM) occurs. Range error (ERANGE) may occur.