Function rgsl::gamma_beta::gamma::gammastar

pub fn gammastar(x: f64) -> f64

This routine computes the regulated Gamma Function \Gamma^*(x) for x > 0. The regulated gamma function is given by,

\Gamma^*(x) = \Gamma(x)/(\sqrt{2\pi} x^{(x-1/2)} \exp(-x))

            = (1 + (1/12x) + ...)  for x to infty

and is a useful suggestion of Temme.