EXPM1(3) Linux Programmer s Manual EXPM1(3)
NAME expm1, expm1f, expm1l - exponential minus 1
SYNOPSIS #include <math.h>
double expm1(double x); float expm1f(float x); long double expm1l(long double x);
Link with -lm.
DESCRIPTION expm1(x) returns a value equivalent to exp (x) - 1. It is computed in a way that is accurate even if the value of x is near zero a case where exp (x) - 1 would be inaccurate due to subtraction of two numbers that are nearly equal.
CONFORMING TO BSD, C99. The float and long double variants are C99 requirements.
SEE ALSO exp(3), log(3), log1p(3)