Book:Murray R. Spiegel/Mathematical Handbook of Formulas and Tables/Chapter 35/Exponential Integral

Exponential Integral $\ds \map \Ei x = \int_x^\infty \frac {e^{-t} } t \rd t$

$35.7$: Characterization of Exponential Integral Function

$35.8$: Power Series Expansion for Exponential Integral Function

$35.9$: Asymptotic Expansion for Exponential Integral Function

$35.10$: Limit to Infinity of Exponential Integral Function