Maxima Function
psi [n](x)
The derivative of log (gamma (x)) of order n+1.
Thus, psi[0](x) is the first derivative,
psi[1](x) is the second derivative, etc.
Maxima does not know how, in general, to compute a numerical value of
psi, but it can compute some exact values for rational args.
Several variables control what range of rational args psi will
return an exact value, if possible. See ,
maxpsinegint, maxpsifracnum, and maxpsifracnum.
That is, x must lie between maxpsinegint and
maxpsiposint. If the absolute value of the fractional part of
x is rational and has a numerator less than maxpsifracnum
and has a denominator less than maxpsifracdenom, psi
will return an exact value.
The function bfpsi in the bffac package can compute
numerical values.