RINT
Section: Linux Programmer's Manual (3)
Updated: 2010-09-20
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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():
-
_XOPEN_SOURCE >= 600 || _POSIX_C_SOURCE >= 200112L || _ISOC99_SOURCE;
or
cc -std=c99
rint():
-
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 ||
_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED || _ISOC99_SOURCE ||
_POSIX_C_SOURCE >= 200112L;
or
cc -std=c99
rintf(),
rintl():
-
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE ||
_POSIX_C_SOURCE >= 200112L;
or
cc -std=c99
DESCRIPTION
The
nearbyint()
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.
The
rint()
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.
CONFORMING TO
C99, POSIX.1-2001.
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 3.27 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/.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- CONFORMING TO
-
- NOTES
-
- SEE ALSO
-
- COLOPHON
-
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Time: 19:49:24 GMT, April 27, 2011