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


       #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


       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.


       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.


       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.


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


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




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