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():
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 ||
_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED || _ISOC99_SOURCE ||
_POSIX_C_SOURCE >= 200112L;
or cc -std=c99
nextafterf(), nextafterl():
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 ||
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
or cc -std=c99
nexttoward(), nexttowardf(), nexttowardl():
_XOPEN_SOURCE >= 600 || _ISOC99_SOURCE ||
_POSIX_C_SOURCE >= 200112L;
or cc -std=c99
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
An overflow floating-point exception (FE_OVERFLOW) is raised.
Range error: result is subnormal or underflows
An underflow floating-point exception (FE_UNDERFLOW) is raised.
These functions do not set errno.
ATTRIBUTES
Multithreading (see pthreads(7))
The nextafter(), nextafterf(), nextafterl(), nexttoward(), nextto‐
wardf(), and nexttowardl() functions are thread-safe.
CONFORMING TO
C99, POSIX.1-2001. This function is defined in IEC 559 (and the appen‐
dix with recommended functions in IEEE 754/IEEE 854).
BUGS
In glibc version 2.5 and earlier, these functions do not raise an
underflow floating-point (FE_UNDERFLOW) exception when an underflow
occurs.
SEE ALSOnearbyint(3)COLOPHON
This page is part of release 3.55 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/.
GNU 2013-09-02 NEXTAFTER(3)