Exponential Integral

exponential integral

[‚ek·spə′nen·chəl ′int·ə·grəl]

(mathematics)

The function defined to be the integral from x to ∞ of (e ^-t / t) dt for x positive.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Exponential Integral

 

a special function defined by the integral

This integral cannot be expressed in closed form through elementary functions. If x > 0, then the integral is understood in the sense of its principal value:

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.