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man:nextafterf

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)

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