NEXTAFTERSection: Linux Programmer's Manual (3)
Index Return to Main Contents
NAMEnextafter, nextafterf, nextafterl, nexttoward, nexttowardf, nexttowardl - floating-point number manipulation
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)):
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 || _ISOC99_SOURCE; or
nextafterf(), nextafterl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE; or cc -std=c99
nexttoward(), nexttowardf(), nexttowardl(): _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE; cc -std=c99
DESCRIPTIONThe nextafter() 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 y.
If x equals y, the functions return y.
RETURN VALUEOn 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.
ERRORSSee 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.
CONFORMING TOC99, POSIX.1-2001. This function is defined in IEC 559 (and the appendix with recommended functions in IEEE 754/IEEE 854).
BUGSIn glibc version 2.5 and earlier, these functions do not raise an underflow floating-point (FE_UNDERFLOW) exception when an underflow occurs.
COLOPHONThis page is part of release 3.21 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/.