Function lambert_wm1

pub fn lambert_wm1(z: f64, mode: LambertWAccuracyMode) -> f64

The secondary branch of the Lambert W function, W_-1(z).

Returns NAN if the given input is positive or smaller than -1/e (≈ -0.36787944117144233).

Use Precise for 50 bits of accuracy and the Simple mode for only 24 bits, but with faster execution time.

Wrapper of the lambert_w_m1 and sp_lambert_w_m1 functions of the puruspe crate.

Reference

Toshio Fukushima, Precise and fast computation of Lambert W function by piecewise minimax rational function approximation with variable transformation