Digamma function

The digamma function, denoted as \( \psi(x) \), is the logarithmic derivative of the gamma function \( \Gamma(x) \). Mathematically, it is defined as: \[ \psi(x) = \frac{d}{dx} \ln(\Gamma(x)) = \frac{\Gamma'(x)}{\Gamma(x)} \] where \( \Gamma'(x) \) is the derivative of the gamma function.