changes.mady.by.user Arthur Aslanyan (Nafta College)
Saved on Mar 23, 2019
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Fig. 1. A sample graph of
{\rm Ei}(0) = -\infty
{\rm Ei}(-\infty) = 0
{\rm Ei}(+\infty) = +\infty
\frac{d }{dx}{\rm Ei}(x) = \frac{e^x}{x}
{\rm Ei}(x) = \gamma + \ln |x| + \sum_{k=1}^\infty \frac{x^k}{k\cdot k!}
{\rm Ei}(x) = e^x \, \left[ \frac{1}{x} + \sum_{k=2}^\infty \frac{(k-1)!}{x^k} \right]
where
{\rm Ei}(-x) \sim \gamma + \ln x
{\rm Ei}(x) \sim \gamma + \ln x
