SpecFunc_Ei

SpecFunc_Ei(*args)

Exponential integral function.

\forall z \in \Cset, \quad \mathrm{Ei}(z) = -\int_{-z}^{\infty} \frac{\exp(-t)}{t}\di{t}

Parameters:
z : float or complex
Returns:
result : float or complex (same as z)