man:log1pf
LOG1P(3) Linux Programmer's Manual LOG1P(3)
NAME
log1p, log1pf, log1pl - logarithm of 1 plus argument
SYNOPSIS
#include <math.h>
double log1p(double x); float log1pf(float x); long double log1pl(long double x);
Link with -lm.
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
log1p(): _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 500 || /* Since glibc 2.19: */ _DEFAULT_SOURCE || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE log1pf(), log1pl(): _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || /* Since glibc 2.19: */ _DEFAULT_SOURCE || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
DESCRIPTION
These functions return a value equivalent to
log (1 + x)
The result 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).
If x is a NaN, a NaN is returned.
If x is positive infinity, positive infinity is returned.
If x is -1, a pole error occurs, and the functions return -HUGE_VAL, -HUGE_VALF, or -HUGE_VALL, respectively.
If x is less than -1 (including negative infinity), a domain error occurs, and a NaN (not a number) is returned.
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 errno is set to EDOM (but see BUGS). An invalid floating-point exception (FE_INVALID) is raised.
Pole error: x is -1 errno is set to ERANGE (but see BUGS). A divide-by-zero float- ing-point exception (FE_DIVBYZERO) is raised.
ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).
allbox; lbw27 lb lb l l l. Interface Attribute Value T{ log1p(), log1pf(), log1pl() T} Thread safety MT-Safe
CONFORMING TO
C99, POSIX.1-2001, POSIX.1-2008.
BUGS
Before version 2.22, the glibc implementation did not set errno to EDOM when a domain error occurred.
Before version 2.22, the glibc implementation did not set errno to ERANGE when a range error occurred.
SEE ALSO
exp(3), expm1(3), log(3)
COLOPHON
This page is part of release 4.16 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.
2017-09-15 LOG1P(3)
/data/webs/external/dokuwiki/data/pages/man/log1pf.txt · Last modified: 2019/05/17 09:32 by 127.0.0.1