NAME

       nextafter,   nextafterf,   nextafterl,  nexttoward,  nexttowardf,  nexttowardl  -  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():
           _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

       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
              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.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).
       ┌──────────────────────────────┬───────────────┬─────────┐
       │ Interface                    │ Attribute     │ Value   │
       ├──────────────────────────────┼───────────────┼─────────┤
       │ nextafter(), nextafterf(),   │ Thread safety │ MT-Safe │
       │ nextafterl(), nexttoward(),  │               │         │
       │ nexttowardf(), nexttowardl() │               │         │
       └──────────────────────────────┴───────────────┴─────────┘

CONFORMING TO

       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

       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

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       information  about  reporting  bugs,  and  the  latest  version  of  this   page,   can   be   found   at
       https://www.kernel.org/doc/man-pages/.

GNU                                                2017-09-15                                       NEXTAFTER(3)