Psi takes as arguments a real a and an integer n (by
default n=0).
Psi returns the value of the n-th derivative of the DiGamma function
at x=a, where the DiGamma function is the first derivative
of ln(Γ(x)). This function is used to evaluated sums of
rational functions having poles at integers.
Input :
Output :
^
2/6-5/4If n=0, you may use Psi(a) instead of Psi(a,0)
to compute the value of the DiGamma function at x=a.
Input :
Output :
Input :
Output :