Man page - log1pl(3)

Packages contains this manual

Available languages:

en fr pl ja ru ro de

Manual

log1p

NAME
LIBRARY
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
ATTRIBUTES
STANDARDS
HISTORY
BUGS
SEE ALSO

NAME

log1p, log1pf, log1pl - logarithm of 1 plus argument

LIBRARY

Math library ( libm , -lm )

SYNOPSIS

#include <math.h>

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)):

log1p ():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| _XOPEN_SOURCE >= 500
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

log1pf (), log1pl ():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 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 floating-point exception ( FE_DIVBYZERO ) is raised.

ATTRIBUTES

For an explanation of the terms used in this section, see attributes (7).

Image grohtml-214818-1.png

STANDARDS

C11, POSIX.1-2008.

HISTORY

C99, POSIX.1-2001.

BUGS

Before glibc 2.22, the glibc implementation did not set errno to EDOM when a domain error occurred.

Before glibc 2.22, the glibc implementation did not set errno to ERANGE when a range error occurred.

SEE ALSO

exp (3), expm1 (3), log (3)