nextafter, nextafterf, nextafterl, nexttoward, nexttowardf, nexttowardl - floating-point number manipulation
Math library (libm
, -lm
)
#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);
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 <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
nextafterf(), nextafterl():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
nexttoward(), nexttowardf(), nexttowardl():
_XOPEN_SOURCE >= 600 || _ISOC99_SOURCE
|| _POSIX_C_SOURCE >= 200112L
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.
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.
See math_error(7) for information on how to determine whether an error has occurred when calling these functions.
The following errors can occur:
errno
is set to ERANGE. An overflow
floating-point exception (FE_OVERFLOW) is raised.
errno
is set to ERANGE. An underflow
floating-point exception (FE_UNDERFLOW) is raised.
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 |
C11, POSIX.1-2008.
This function is defined in IEC 559 (and the appendix with recommended functions in IEEE 754/IEEE 854).
C99, POSIX.1-2001.
In glibc 2.5 and earlier, these functions do not raise an underflow floating-point (FE_UNDERFLOW) exception when an underflow occurs.
Before glibc 2.23 these functions did not set errno
.
nearbyint(3)