Formula:2948

Digital Library of Mathematical Functions ID 6.6.E3

${\displaystyle{\displaystyle E_{1}\left(z\right)=-\ln z+e^{-z}\sum_{n=0}^{\infty}\frac{z^{n}}{n!}\psi\left(n+1\right),}}$

Symbols List

• ${\displaystyle{\displaystyle\psi\left(\NVar{z}\right)}}$: psi (or digamma) function
• ${\displaystyle{\displaystyle\mathrm{e}}}$: base of natural logarithm
• ${\displaystyle{\displaystyle E_{1}\left(\NVar{z}\right)}}$: exponential integral
• ${\displaystyle{\displaystyle!}}$:
• ${\displaystyle{\displaystyle\ln\NVar{z}}}$: principal branch of logarithm function
• ${\displaystyle{\displaystyle z}}$: complex variable
• ${\displaystyle{\displaystyle n}}$: nonnegative integer
 

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