nextafter(3)               Library Functions Manual               nextafter(3)

NAME
       nextafter, nextafterf, nextafterl, nexttoward, nexttowardf, nexttowardl
       - floating-point number manipulation

LIBRARY
       Math library (libm, -lm)

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);

   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

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
              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 (), | Thread safety | MT-Safe |
       |nexttoward (), nexttowardf (), nexttowardl  |               |         |
       |()                                          |               |         |
       +--------------------------------------------+---------------+---------+
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)

Linux man-pages 6.8               2024-05-02                      nextafter(3)