Function lanczos_gamma 

pub fn lanczos_gamma(z: f64) -> f64

Lanczos approximation for Gamma function (for numerical evaluation)

Provides accurate numerical evaluation using the Lanczos approximation with 14-digit precision. This is used for non-special values.

Input Validation

• NaN or infinity inputs return NaN
• Non-positive integers (poles) return infinity

Examples

use mathhook_core::functions::special::lanczos_gamma;

let result = lanczos_gamma(5.0);
assert!((result - 24.0).abs() < 1e-10);

let half = lanczos_gamma(0.5);
let sqrt_pi = std::f64::consts::PI.sqrt();
assert!((half - sqrt_pi).abs() < 1e-14);