Symmetry relation of exponential integral E

Theorem

The following formula holds: $$E_n(\overline{z})=\overline{E_n(z)},$$ where $E_n$ denotes the exponential integral E and $\overline{z}$ denotes the complex conjugate.

References

• 1964: Milton Abramowitz and Irene A. Stegun: Handbook of mathematical functions ... (previous) ... (next): $5.1.13$