NEXTAFTER(3) Linux Programmer's Manual NEXTAFTER(3)
NAME
nextafter, nextafterf, nextafterl, nexttoward, nexttowardf, nexttowardl
- floating-point number manipulation
SYNOPSIS
#include <math.h>
double nextafter(double x, double y);
float nextafterf(float x, float y);
long double nextafterl(long double x, long double y);
double nexttoward(double x, long double y);
float nexttowardf(float x, long double y);
long double nexttowardl(long double x, long double y);
Link with -lm.
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
nextafter():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| _XOPEN_SOURCE >= 500
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
nextafterf(), nextafterl():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
nexttoward(), nexttowardf(), nexttowardl():
_XOPEN_SOURCE >= 600 || _ISOC99_SOURCE ||
_POSIX_C_SOURCE >= 200112L
DESCRIPTION
The nextafter(), nextafterf(), and nextafterl() functions return the
next representable floating-point value following x in the direction of
y. If y is less than x, these functions will return the largest repre-
sentable number less than x.
If x equals y, the functions return y.
The nexttoward(), nexttowardf(), and nexttowardl() functions do the
same as the corresponding nextafter() functions, except that they have
a long double second argument.
RETURN VALUE
On success, these functions return the next representable floating-
point value after x in the direction of y.
If x equals y, then y (cast to the same type as x) is returned.
If x or y is a NaN, a NaN is returned.
If x is finite, and the result would overflow, a range error occurs,
and the functions return HUGE_VAL, HUGE_VALF, or HUGE_VALL, respec-
tively, with the correct mathematical sign.
If x is not equal to y, and the correct function result would be sub-
normal, zero, or underflow, a range error occurs, and either the cor-
rect value (if it can be represented), or 0.0, 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:
Range error: result overflow
errno is set to ERANGE. An overflow floating-point exception
(FE_OVERFLOW) is raised.
Range error: result is subnormal or underflows
errno is set to ERANGE. An underflow floating-point exception
(FE_UNDERFLOW) is raised.
ATTRIBUTES
For an explanation of the terms used in this section, see at-
tributes(7).
+-----------------------------+---------------+---------+
|Interface | Attribute | Value |
+-----------------------------+---------------+---------+
|nextafter(), nextafterf(), | Thread safety | MT-Safe |
|nextafterl(), nexttoward(), | | |
|nexttowardf(), nexttowardl() | | |
+-----------------------------+---------------+---------+
CONFORMING TO
C99, POSIX.1-2001, POSIX.1-2008. This function is defined in IEC 559
(and the appendix with recommended functions in IEEE 754/IEEE 854).
BUGS
In glibc version 2.5 and earlier, these functions do not raise an un-
derflow floating-point (FE_UNDERFLOW) exception when an underflow oc-
curs.
BUGS
Before glibc version 2.23 these functions did not set errno.
SEE ALSO
nearbyint(3)
COLOPHON
This page is part of release 5.07 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/.
GNU 2020-06-09 NEXTAFTER(3)