const CENTRAL_REACH: f64 = 2.5;Expand description
The expansion about x = 0 is used for (ν + 1/2)|x| <= CENTRAL_REACH (well conditioned)
and |x| <= CENTRAL_LIMIT (or CENTRAL_LIMIT_POSITIVE for x > 0, where the
series about x = 1 is cheaper), for degrees and orders that keep 1/Γ cheap.