NEXTAFTER(3) libc math functions NEXTAFTER(3)NAME
nextafter, nexttoward - 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);
DESCRIPTION
The nextafter() functions return the next representable neighbor of x in the direction towards y. The size of the step between x and the
result depends on the type of the result. If x = y the function simply returns y. If either value is NaN, then NaN is returned. Other-
wise a value corresponding to the value of the least significant bit in the mantissa is added or subtracted, depending on the direction.
The nexttoward() functions do the same as the nextafter() functions, except that they have a long double second argument.
These functions will signal overflow or underflow if the result goes outside of the range of normalized numbers.
CONFORMING TO
C99. This function is defined in IEC 559 (and the appendix with recommended functions in IEEE 754/IEEE 854).
SEE ALSO nearbyint(3)GNU 2002-08-10 NEXTAFTER(3)
Check Out this Related Man Page
NEXTAFTER(3) Linux Programmer's Manual NEXTAFTER(3)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(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 || _ISOC99_SOURCE; or cc -std=c99
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
DESCRIPTION
The 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 x.
If x equals y, the functions return y.
The nexttoward() functions do the same as the 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, respec-
tively, 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 cor-
rect 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.
CONFORMING TO
C99, POSIX.1-2001. 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 3.25 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/.
GNU 2009-12-05 NEXTAFTER(3)