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

NAME         top

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

SYNOPSIS         top

       #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
           _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         top

       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         top

       These functions return the rounded integer value.

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

ERRORS         top

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

ATTRIBUTES         top

       For an explanation of the terms used in this section, see

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

CONFORMING TO         top

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

NOTES         top

       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)

SEE ALSO         top

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

COLOPHON         top

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       latest version of this page, can be found at

                                 2016-03-15                          RINT(3)