Function wigner3j 

pub fn wigner3j(j1: i32, j2: i32, j3: i32, m1: i32, m2: i32, m3: i32) -> f64

Wigner 3j symbol (j1 j2 j3; m1 m2 m3), zero outside the admissible labels.

Evaluated with treams’ two-sided recurrence, continued in each direction for as long as the symbols grow (see visit).

Upstream: treams.special.wigner3j. Differences: more accurate for large j with extreme orders, and equal up to rounding elsewhere; negative j gives zero, where treams raises ValueError.