nearbyint(3)

NAME

   nearbyint,  nearbyintf,  nearbyintl,  rint,  rintf,  rintl  -  round to
   nearest integer

SYNOPSIS

   #include <math.h>

   double nearbyint(double x);
   float nearbyintf(float x);
   long double nearbyintl(long double x);

   double rint(double x);
   float rintf(float x);
   long double rintl(long double x);

   Link with -lm.

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

   nearbyint(), nearbyintf(), nearbyintl():
       _POSIX_C_SOURCE >= 200112L || _ISOC99_SOURCE
   rint():
       _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
           || _XOPEN_SOURCE >= 500
           || /* Since glibc 2.19: */ _DEFAULT_SOURCE
           || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
   rintf(), rintl():
       _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
           || /* Since glibc 2.19: */ _DEFAULT_SOURCE
           || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION

   The nearbyint(), nearbyintf(), and nearbyintl() functions  round  their
   argument  to  an  integer  value  in  floating-point  format, using the
   current rounding direction (see fesetround(3)) and without raising  the
   inexact  exception.  When the current rounding direction is to nearest,
   these functions round halfway cases to the even integer  in  accordance
   with IEEE-754.

   The  rint(), rintf(), and rintl() functions do the same, but will raise
   the inexact exception (FE_INEXACT, checkable via fetestexcept(3))  when
   the result differs in value from the argument.

RETURN VALUE

   These functions return the rounded integer value.

   If x is integral, +0, -0, NaN, or infinite, x itself is returned.

ERRORS

   No  errors  occur.  POSIX.1-2001 documents a range error for overflows,
   but see NOTES.

ATTRIBUTES

   For  an  explanation  of  the  terms  used   in   this   section,   see
   attributes(7).

   
   Interface                   Attribute      Value   
   
   nearbyint(), nearbyintf(),  Thread safety  MT-Safe 
   nearbyintl(), rint(),                              
   rintf(), rintl()                                   
   

CONFORMING TO

   C99, POSIX.1-2001, POSIX.1-2008.

NOTES

   SUSv2  and  POSIX.1-2001  contain  text about overflow (which might set
   errno to ERANGE, or raise an FE_OVERFLOW exception).  In practice,  the
   result  cannot  overflow on any current machine, so this error-handling
   stuff is just nonsense.  (More precisely, overflow can happen only when
   the  maximum  value  of  the  exponent  is  smaller  than the number of
   mantissa bits.  For the IEEE-754 standard 32-bit and  64-bit  floating-
   point  numbers  the maximum value of the exponent is 128 (respectively,
   1024), and the number of mantissa bits is 24 (respectively, 53).)

   If you want to store the rounded value in an integer type, you probably
   want to use one of the functions described in lrint(3) instead.

SEE ALSO

   ceil(3), floor(3), lrint(3), round(3), trunc(3)

COLOPHON

   This  page  is  part of release 4.09 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/.

                              2016-03-15                           RINT(3)

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