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EXPM1(3) | Linux Programmer's Manual | EXPM1(3) |
NAME¶
expm1, expm1f, expm1l - exponential minus 1SYNOPSIS¶
#include <math.h>Link with -lm.double expm1(double x);float expm1f(float x);long double expm1l(long double x);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
_BSD_SOURCE || _SVID_SOURCE ||
_XOPEN_SOURCE >= 500 ||
_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED || _ISOC99_SOURCE ||
_POSIX_C_SOURCE >= 200112L;
or cc -std=c99
_BSD_SOURCE || _SVID_SOURCE ||
_XOPEN_SOURCE >= 600 || _ISOC99_SOURCE ||
_POSIX_C_SOURCE >= 200112L;
or cc -std=c99
DESCRIPTION¶
expm1(x) returns a value equivalent toexp(x) - 1It 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.
RETURN VALUE¶
On success, these functions return exp(x) - 1.ERRORS¶
See math_error(7) for information on how to determine whether an error has occurred when calling these functions. The following errors can occur:- Range error, overflow
- errno is set to ERANGE (but see BUGS). An overflow floating-point exception (FE_OVERFLOW) is raised.
CONFORMING TO¶
C99, POSIX.1-2001.BUGS¶
For some large negative x values (where the function result approaches -1), expm1() raises a bogus underflow floating-point exception.SEE ALSO¶
exp(3), log(3), log1p(3)COLOPHON¶
This page is part of release 3.44 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.2010-09-12 |