NEXTAFTER
Section: Linux Programmer's Manual (3)
Updated: 2017-09-15
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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 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 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,
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 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
For an explanation of the terms used in this section, see
attributes(7).
| Interface | Attribute | Value
|
nextafter(),
nextafterf(),
nextafterl(),
nexttoward(),
nexttowardf(),
nexttowardl()
| Thread safety | MT-Safe
|
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 underflow
floating-point
(
FE_UNDERFLOW)
exception when an underflow occurs.
SEE ALSO
nearbyint(3)
COLOPHON
This page is part of release 4.13 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/.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- ATTRIBUTES
-
- CONFORMING TO
-
- BUGS
-
- SEE ALSO
-
- COLOPHON
-
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- Running on 
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