expm1, expm1f : exponential minus 1

Synopsis

#include <math.h>
double expm1(double x);
float expm1f(float x);
```### Description

expm1 and expm1f calculate the exponential of x and subtract 1, that is, is the base of the natural system of logarithms, approximately 2.71828). The result is accurate even for small values of x, where using exp(x)-1 would lose many significant digits.### Returns

e raised to the power x, minus 1.

---

**Authoritative source**: BUSMASTER DITA help source `expm1.dita`, compiled into `BUSMASTER.CHM` with the application.