- 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 y.

       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 sub-
       normal, 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.

       dix 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 3.23 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/.