Function rgsl::gamma_beta::pochhammer_symbol::lnpoch_sgn_e

pub fn lnpoch_sgn_e(a: f64, x: f64, sgn: &mut f64) -> (Value, Result)

These routines compute the sign of the Pochhammer symbol and the logarithm of its magnitude. The computed parameters are result = \log(|(a)_x|) with a corresponding error term, and sgn = \sgn((a)_x) where (a)_x = \Gamma(a + x)/\Gamma(a).