| 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. |
NAME
nextafter, nextafterf, nextafterl, nexttoward, nexttowardf, nexttowardl - floating-point number manipulation
LIBRARY
Math library (libm, -lm)
SYNOPSIS
#include <math.h>double nextafter(double \nx\n, double \ny\n);\n
\nfloat nextafterf(float \nx\n, float \ny\n);\n
\nlong double nextafterl(long double \nx\n, long double \ny\n);double nexttoward(double \nx\n, long double \ny\n);\n
\nfloat nexttowardf(float \nx\n, long double \ny\n);\n
\nlong double nexttowardl(long double \nx\n, long double \ny\n);nextafter():
\n
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
\n
|| _XOPEN_SOURCE >= 500
\n
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
\n
|| /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCEnextafterf(), nextafterl():
\n
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
\n
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
\n
|| /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCEnexttoward(), nexttowardf(), nexttowardl():
\n
_XOPEN_SOURCE >= 600 || _ISOC99_SOURCE
\n
|| _POSIX_C_SOURCE >= 200112LDESCRIPTION
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
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 attributes(7).
| Interface | Attribute | Value |
| nextafter (), nextafterf (), nextafterl (), nexttoward (), nexttowardf (), nexttowardl () | Thread safety | MT-Safe |
STANDARDS
C11, POSIX.1-2008.
This function is defined in IEC 559 (and the appendix with recommended functions in IEEE 754/IEEE 854).
HISTORY
C99, POSIX.1-2001.
BUGS
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.
SEE ALSO
nearbyint(3)