expint

double expint(int n, double x);

Evaluates the exponential integral En(x).

Parameters:
n?
x?

Returns:
En(x)

Errors:
NUMERICS_ERROR is raised if n < 0, if x < 0, if n = x = 0, or if x = 0 and n = 1.

Header:
#include "mathx.h"