double ExpEI(double X);
Scaled exponential integral exp(-x)*Ei(x).
| # | Name | Type | Description |
|---|---|---|---|
| 1 | X | double | Argument of the scaled exponential integral; must not be zero. |
Returns: the scaled exponential integral exp(-x)*Ei(x).
Remarks:
Computes the exponentially scaled exponential integral
e^(-x) Ei(x),
which removes the dominant e^{x} growth of Ei for large positive x and decays like 1/x, avoiding overflow. For large x it tends to 0 from above. Domain: any real x \ne 0 (same singularity at the origin as Ei).
See Also: SpecialFuncs::EI, SpecialFuncs::E1
Declared in Dew::Math::Units::SpecialFuncs · Dew.Math/Units.SpecialFuncs.h · Cross-compiler