expInt

expInt (n, x)

The expInt function returns the value of the exponential integral E_n (x ):

$$\displaystyle E_{n}(x)=P \int_{1}^{\infty} \frac{e^{-x t}}{t^{n}} d t \quad(x>0 ; n=0,1,2 \ldots).$$

See Also

ei, ExpIntegralE1

References

Abramowitz, M., and I.A. Stegun, "Handbook of Mathematical Functions", 446 pp., Dover, New York, 1972.