A lesser-known characterization of the gamma function

The gamma function Γ(z) extends the factorial function from integers to complex numbers. (Technically, Γ(z + 1) extends factorial.) There are other ways to extend the factorial function, so what makes the gamma function the right choice? The most common answer is the Bohr-Mollerup theorem. This theorem says that if f: (0, ∞) → (0, […] The post A lesser-known characterization of the gamma function first appeared on John D. Cook.