Editing Exponential integral (section)

{{Short description|Special function defined by an integral}}
{{distinguish|text=[[List of integrals of exponential functions|other integrals]] of [[exponential function]]s}}
{{Use American English|date = January 2019}}
[[File:Plot of the exponential integral function E n(z) with n=2 in the complex plane from -2-2i to 2+2i with colors created with Mathematica 13.1 function ComplexPlot3D.svg|alt=Plot of the exponential integral function E n(z) with n=2 in the complex plane from -2-2i to 2+2i with colors created with Mathematica 13.1 function ComplexPlot3D|thumb|Plot of the exponential integral function E n(z) with n=2 in the complex plane from -2-2i to 2+2i with colors created with Mathematica 13.1 function ComplexPlot3D]]In mathematics, the '''exponential integral''' Ei is a [[special function]] on the [[complex plane]].
It is defined as one particular [[definite integral]] of the ratio between an [[exponential function]] and its [[argument of a function|argument]].