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LOG1P(3) | Linux Programmer's Manual | LOG1P(3) |
NAME¶
log1p, log1pf, log1pl - logarithm of 1 plus argumentSYNOPSIS¶
#include <math.h>Link with -lm.double log1p(double x);float log1pf(float x);long double log1pl(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¶
log1p(x) returns a value equivalent tolog (1 + x)It is computed in a way that is accurate even if the value of x is near zero.
RETURN VALUE¶
On success, these functions return the natural logarithm of (1 + x).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:- Domain error: x is less than -1
- An invalid floating-point exception (FE_INVALID) is raised.
- Pole error: x is -1
- A divide-by-zero floating-point exception (FE_DIVBYZERO) is raised.
CONFORMING TO¶
C99, POSIX.1-2001.SEE ALSO¶
exp(3), expm1(3), log(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/.2010-09-20 |