- 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)):

           _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 ||
           _POSIX_C_SOURCE >= 200112L;
           or cc -std=c99
       nextafterf(), nextafterl():
           _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 ||
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
           or cc -std=c99
       nexttoward(), nexttowardf(), nexttowardl():
           _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE ||
           _POSIX_C_SOURCE >= 200112L;
           or 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, respec-
       tively, with the correct mathematical sign.

       If x is not equal to y, and the correct function result would  be  sub-
       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 appen-
       dix 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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GNU                               2010-09-20                      NEXTAFTER(3)
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