pub fn gamma(x: &DBig, precision: usize) -> OxiNumResult<DBig>Expand description
Compute the Gamma function Γ(x) to precision significant decimal digits.
Uses Lanczos approximation (g=7) for x ∈ (0, 20], Stirling series for x > 20, and the reflection formula Γ(x)·Γ(1-x) = π/sin(πx) for x < 0.
§Errors
Returns OxiNumError::Domain if x is zero or a negative integer (poles
of the Gamma function).