EXPM1(3)

NAME
1.17 `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, 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).

SEE ALSO
expm1 is part of the library. The full documentation for is maintained as a Texinfo manual. If info and are properly installed at your site, the command

    info

will give you access to the complete manual.