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Section: Linux Programmer's Manual (3) Updated: 20150302 Index
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NAME
nextafter, nextafterf, nextafterl, nexttoward, nexttowardf, nexttowardl 
floatingpoint 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 floatingpoint value following
x
in the direction of
y.
If
y
is less than
x,
these functions will return the largest representable 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 floatingpoint 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,
respectively, with the correct mathematical sign.
If
x
is not equal to
y,
and the correct function result would be subnormal, zero, or underflow,
a range error occurs,
and either the correct 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 floatingpoint exception
(FE_OVERFLOW)
is raised.
 Range error: result is subnormal or underflows

An underflow floatingpoint exception
(FE_UNDERFLOW)
is raised.
These functions do not set
errno.
ATTRIBUTES
For an explanation of the terms used in this section, see
attributes(7).
Interface  Attribute  Value

nextafter(),
nextafterf(),
nextafterl(),
nexttoward(),
nexttowardf(),
nexttowardl()
 Thread safety  MTSafe

CONFORMING TO
C99, POSIX.12001.
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 underflow
floatingpoint
(FE_UNDERFLOW)
exception when an underflow occurs.
SEE ALSO
nearbyint(3)
COLOPHON
This page is part of release 3.81 of the Linux
manpages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
http://www.kernel.org/doc/manpages/.
Index
 NAME

 SYNOPSIS

 DESCRIPTION

 RETURN VALUE

 ERRORS

 ATTRIBUTES

 CONFORMING TO

 BUGS

 SEE ALSO

 COLOPHON

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