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.\" Copyright 2001 Andries Brouwer <aeb@cwi.nl>.
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2008-08-01 05:26:39 +00:00
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.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
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.\" <mtk.manpages@gmail.com>
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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2007-04-12 22:42:49 +00:00
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.\"
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2004-11-03 13:51:07 +00:00
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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2007-04-12 22:42:49 +00:00
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.\"
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2004-11-03 13:51:07 +00:00
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\"
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2008-08-01 05:54:27 +00:00
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.TH RINT 3 2008-08-05 "" "Linux Programmer's Manual"
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.SH NAME
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nearbyint, nearbyintf, nearbyintl, rint, rintf, rintl \- round
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to nearest integer
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.SH SYNOPSIS
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.nf
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.B #include <math.h>
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.sp
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.BI "double nearbyint(double " x );
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.br
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.BI "float nearbyintf(float " x );
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.br
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.BI "long double nearbyintl(long double " x );
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.sp
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.BI "double rint(double " x );
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.br
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.BI "float rintf(float " x );
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.br
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.BI "long double rintl(long double " x );
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.fi
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.sp
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2007-07-21 05:25:03 +00:00
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Link with \fI\-lm\fP.
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2007-07-08 12:11:40 +00:00
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.sp
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.in -4n
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Feature Test Macro Requirements for glibc (see
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.BR feature_test_macros (7)):
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.in
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.sp
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.ad l
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.BR nearbyint (),
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.BR nearbyintf (),
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.BR nearbyintl ():
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_XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE; or
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.I cc\ -std=c99
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.br
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.BR rint ():
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_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 500 || _ISOC99_SOURCE; or
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.I cc\ -std=c99
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.br
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.BR rintf (),
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.BR rintl ():
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_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE; or
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.I cc\ -std=c99
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.ad b
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.SH DESCRIPTION
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The
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.BR nearbyint ()
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functions round their argument to an integer value in floating-point
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format, using the current rounding direction (see
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.BR fesetround (3))
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and without raising the
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.I inexact
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exception.
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.LP
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The
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.BR rint ()
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functions do the same, but will raise the
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.I inexact
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exception
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.RB ( FE_INEXACT ,
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checkable via
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.BR fetestexcept (3))
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when the result differs in value from the argument.
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.SH "RETURN VALUE"
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These functions return the rounded integer value.
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If \fIx\fP is integral, +0, \-0, NaN, or infinite,
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\fIx\fP itself is returned.
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.SH ERRORS
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No errors occur.
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2008-08-04 16:00:58 +00:00
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POSIX.1-2001 documents a range error for overflows, but see NOTES.
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.SH "CONFORMING TO"
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C99, POSIX.1-2001.
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.SH NOTES
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2006-08-03 13:57:30 +00:00
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SUSv2 and POSIX.1-2001 contain text about overflow (which might set
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.I errno
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to
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.BR ERANGE ,
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or raise an
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.B FE_OVERFLOW
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exception).
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In practice, the result cannot overflow on any current machine,
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so this error-handling stuff is just nonsense.
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(More precisely, overflow can happen only when the maximum value
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of the exponent is smaller than the number of mantissa bits.
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For the IEEE-754 standard 32-bit and 64-bit floating-point numbers
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the maximum value of the exponent is 128 (respectively, 1024),
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and the number of mantissa bits is 24 (respectively, 53).)
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If you want to store the rounded value in an integer type,
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you probably want to use one of the functions described in
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.BR lrint (3)
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instead.
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.SH "SEE ALSO"
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.BR ceil (3),
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.BR floor (3),
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.BR lrint (3),
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.BR round (3),
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.BR trunc (3)
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