## 3.15 Special functions

R lambert_w0(T x)

Implementation of the $$W_0$$ branch of the Lambert W function, i.e., solution to the function $$W_0(x) \exp^{ W_0(x)} = x$$

R lambert_wm1(T x)
Implementation of the $$W_{-1}$$ branch of the Lambert W function, i.e., solution to the function $$W_{-1}(x) \exp^{W_{-1}(x)} = x$$