FNCdigammareturns the value of the digamma function (sometimes called thepsifunction) of the complex valuez,Ψ(z). The value ofΨ(z) approaches ± aszapproaches a real negative integer value or zero.
Errors
FNCdigammacauses an HTBasic error if its argument is not of type COMPLEX or if the magnitude of either the real or imaginary component ofΨ(z) exceeds MAXREAL, the largest number representable.