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



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 repre-
       sentable 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,  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.

       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).

       allbox; lbw28 lb lb l l l.  Interface Attribute Value  T{  nextafter(),
       nextafterf(),
       nextafterl(), nexttoward(),
       nexttowardf(), nexttowardl() T}   Thread safety  MT-Safe

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
       This page is part of release 4.16 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
       https://www.kernel.org/doc/man-pages/.



GNU                               2017-09-15                      NEXTAFTER(3)