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(): _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

DESCRIPTION
       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.

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.

CONFORMING TO
       C99, POSIX.1-2001.  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 3.25 of the Linux man-pages project.  A description of the project,  and  information  about
       reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



GNU                                                        2009-12-05                                               NEXTAFTER(3)