psi( [ n , ] z )
The digamma function of z in SageMath. Defined by
\[ \psi(z) = \frac{ d }{ dz } \ln \Gamma(z) = \frac{ \Gamma(z)' }{ \Gamma(z) } \]The optional integer argument n is used for multiple derivatives.
Plot on the real axis:
Series expansion about the origin:
Special values:
Related functions: gamma
Function category: gamma functions sagemath-docs