Function gamma 

pub fn gamma(x: u64) -> u64

gamma(x)

Extended Factorial Function

Γ(n) is a way to extend the factorial function to all complex numbers except the negative integers and zero. For any positive integer, the Gamma function is defined as:

Γ(n)=(n−1)!

For example, the gamma of 3 (denoted as Γ(3)) is:

Γ(3)=(3−1)! = 2!=2×1=2

By definition, the Gamma function of 0 returns an error because 0 − 1 = − 1, which is not accepted in the factorial function.

Examples

use mathlab::math::gamma;
assert_eq!(gamma(1), 1);
assert_eq!(gamma(2), 1);
assert_eq!(gamma(3), 2);
assert_eq!(gamma(4), 6);
assert_eq!(gamma(4) as u8, 6);
assert_eq!(gamma(4) as i32, 6);
assert_eq!(gamma(4) as f64, 6.0);
assert_eq!(gamma(17), 20922789888000);
assert_eq!(gamma(19), 6402373705728000);

End Fun Doc