Function root_count 

pub fn root_count<E: FloatElement>(re_mu_max: E) -> usize

The number of m-th roots the far field needs when the widest lane’s Re ln z is re_mu_max: the smallest m >= 2 with Re mu / m <= sqrt(alpha^2 - 1) pi = 2.0839 (alpha = 1.2), capped. The identity holds for any m, so the widest lane sets it for the packet. A comparison loop, so no count is converted out of a float.