Digamma

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The digamma function $\psi \colon \mathbb{C} \setminus \{0,-1,-2,\ldots\} \rightarrow \mathbb{C}$ is defined by $$\psi(z) = \dfrac{\mathrm{d}}{\mathrm{d}z} \log \Gamma(z) = \dfrac{\Gamma'(z)}{\Gamma(z)}.$$

Properties[edit]

Partial derivative of beta function
Digamma at 1
Digamma functional equation
Digamma at n+1

See Also[edit]

Gamma
Polygamma
Trigamma

References[edit]