gamma

fnreal gamma(real x)

The Gamma function, Γ(x)

Γ(x) is a generalisation of the factorial function to real and complex numbers. Like x!, Γ(x+1) = x * Γ(x).

Mathematically, if z.re > 0 then Γ(z) = ∫0 tz-1e-t dt

x, Γ(x) NaN, NaN ±0.0, +∞ integer > 0, (x-1)! integer < 0, NaN +∞, +∞ -∞, NaN