NEXTAFTER(3)              Linux Programmer's Manual             NEXTAFTER(3)

NAME         top

       nextafter,  nextafterf,  nextafterl, nexttoward, nexttowardf, nextto‐
       wardl - floating-point number manipulation

SYNOPSIS         top

       #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)):

           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
               || _XOPEN_SOURCE >= 500
               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
       nextafterf(), nextafterl():
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
       nexttoward(), nexttowardf(), nexttowardl():
           _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE ||
           _POSIX_C_SOURCE >= 200112L

DESCRIPTION         top

       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         top

       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         top

       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

       These functions do not set errno.

ATTRIBUTES         top

       For an explanation of the terms used in this section, see

       │Interface                    Attribute     Value   │
       │nextafter(), nextafterf(),   │ Thread safety │ MT-Safe │
       │nextafterl(), nexttoward(),  │               │         │
       │nexttowardf(), nexttowardl() │               │         │

CONFORMING TO         top

       C99, POSIX.1-2001, POSIX.1-2008.  This function is defined in IEC 559
       (and the appendix with recommended functions in IEEE 754/IEEE 854).

BUGS         top

       In glibc version 2.5 and earlier, these functions do not raise an
       underflow floating-point (FE_UNDERFLOW) exception when an underflow

SEE ALSO         top


COLOPHON         top

       This page is part of release 5.05 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at

GNU                              2017-09-15                     NEXTAFTER(3)

Pages that refer to this page: nextup(3)