expm1
, expm1f
—exponential minus 1#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,
e raised to the power x minus 1 (where e
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.
Portability
Neither expm1
nor expm1f
is required by ANSI C or by
the System V Interface Definition (Issue 2).