expm1(3M)
NAME
expm1 − computes exponential functions
SYNOPSIS
cc [ flag ... ] file ... −lm [ library ... ]
#include <math.h>
double expm1(double x);
DESCRIPTION
The expm1() function computes ex−1.0.
RETURN VALUES
If x is NaN, then the function returns NaN.
If x is positive infinity, expm1() returns positive infinity.
If x is negative infinity, expm1() returns −1.0.
If the value overflows, expm1() returns HUGE_VAL.
ERRORS
No errors will occur.
USAGE
The value of expm1(x) may be more accurate than exp(x)−1.0 for small values of x.
The expm1() and log1p(3M) functions are useful for financial calculations of ((1+x)n−1)/x, namely:
expm1(n ∗ log1p(x))/x
when x is very small (for example, when performing calculations with a small daily interest rate). These functions also simplify writing accurate inverse hyperbolic functions.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| MT-Level | MT-Safe |
SEE ALSO
exp(3M), ilogb(3M), log1p(3M), attributes(5)
SunOS 5.6 — Last change: 29 Dec 1996