`ei`

Exponential integral Ei(x).

Category: Mathematics > Mathematical Functions

Syntax

Y = ei(X)

Evaluates Ei(x) for real X.

Description

Ei(x) is the principal value of the integral of exp(t)/t from minus infinity to x. It tends to minus infinity at 0 and grows like exp(x)/x for large x. For positive x it is tied to expint by ei(x) = -real(expint(-x)).

Input arguments

X: Numeric or symbolic array.

Output arguments

Y: Array of the same size.

Example

Values and the expint relation

x = [0.5 2];
ei(x)
-real(expint(-x))

Output

ans = 1×2

    0.4542    4.9542
ans = 1×2

    0.4542    4.9542

See also

expint cosint coshint sinint gamma