(split) LDP v3.24 -> v3.29 の定型的な変更内容を反映。

[linuxjm/LDP_man-pages.git] / draft / man3 / round.3

.\" Copyright 2001 Andries Brouwer <aeb@cwi.nl>.
.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
.\"     <mtk.manpages@gmail.com>
.\"
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date.  The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein.  The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\"
.\" Japanese Version Copyright (c) 2001, 2005 Yuichi SATO
.\" and Copyright (c) 2008 Akihiro MOTOKI
.\" Translated Fri Jul 13 20:33:41 JST 2001
.\"         by Yuichi SATO <ysato@h4.dion.ne.jp>
.\" Updated & Modified Sun Jan 16 07:59:12 JST 2005
.\"         by Yuichi SATO <ysato444@yahoo.co.jp>
.\" Updated 2008-09-16, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>
.\"
.\"WORD:        mantissa        ²¾¿ô
.\"
.TH ROUND 3  2010-09-20 "" "Linux Programmer's Manual"
.\"O .SH NAME
.SH ̾Á°
.\"O round, roundf, roundl \- round to nearest integer, away from zero
round, roundf, roundl \- ºÇ¤â¶á¤¤À°¿ôÃͤ˴ݤá¤ë (2 ¤Ä¤ÎÀ°¿ô¤ÎÃæ´ÖÃͤξì¹ç¤Ï 0 ¤«¤é±ó¤¤Êý¤Ë´Ý¤á¤ë)
.\"O .SH SYNOPSIS
.SH ½ñ¼°
.nf
.B #include <math.h>
.sp
.BI "double round(double " x );
.br
.BI "float roundf(float " x );
.br
.BI "long double roundl(long double " x );
.fi
.sp
.\"O Link with \fI\-lm\fP.
\fI\-lm\fP ¤Ç¥ê¥ó¥¯¤¹¤ë¡£
.sp
.in -4n
.\"O Feature Test Macro Requirements for glibc (see
.\"O .BR feature_test_macros (7)):
glibc ¸þ¤±¤Îµ¡Ç½¸¡ºº¥Þ¥¯¥í¤ÎÍ×·ï
.RB ( feature_test_macros (7)
»²¾È):
.in
.sp
.ad l
.BR round (),
.BR roundf (),
.BR roundl ():
.RS 4
_XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
_POSIX_C_SOURCE\ >=\ 200112L;
.br
or
.I cc\ -std=c99
.RE
.ad
.\"O .SH DESCRIPTION
.SH ÀâÌÀ
.\"O These functions round \fIx\fP to the nearest integer, but
.\"O round halfway cases away from zero (regardless of the current rounding
.\"O direction, see
.\"O .BR fenv (3)),
.\"O instead of to the nearest even integer like
.\"O .BR rint (3).
¤³¤ì¤é¤Î´Ø¿ô¤Ï \fIx\fP ¤òºÇ¤â¶á¤¤À°¿ôÃͤ˴ݤá¤ë¡£
2 ¤Ä¤ÎÀ°¿ô¤ÎÃæ´ÖÃͤξì¹ç¤Ï¡¢
.BR rint (3)
¤Î¤è¤¦¤ËºÇ¤â¶á¤¤¶ö¿ô¤Ë´Ý¤á¤¿¤ê¤»¤º¤Ë¡¢
(¸½ºß¤Î´Ý¤áÊý¸þ¤Ë´Ø·¸¤Ê¤¯) 0 ¤«¤é±ó¤¤Êý¤Ë´Ý¤á¤ë
(´Ý¤áÊý¸þ¤Ë¤Ä¤¤¤Æ¤Ï
.BR fenv (3)
¤ò»²¾È)¡£

.\"O For example,
.\"O .IR round(0.5)
.\"O is 1.0, and
.\"O .IR round(\-0.5)
.\"O is \-1.0.
Î㤨¤Ð¡¢
.I round(0.5)
¤Ï 1.0 ¤Ç¡¢
.I round(\-0.5)
¤Ï \-1.0 ¤Ç¤¢¤ë¡£
.\"O .SH "RETURN VALUE"
.SH ÊÖ¤êÃÍ
.\"O These functions return the rounded integer value.
¤³¤ì¤é¤Î´Ø¿ô¤Ï´Ý¤á¤¿À°¿ôÃͤòÊÖ¤¹¡£

.\"O If \fIx\fP is integral, +0, \-0, NaN,  or infinite,
.\"O \fIx\fP itself is returned.
\fIx\fP ¤¬À°¿ô¡¢+0¡¢\-0¡¢NaN¡¢Ìµ¸Â¤Î¤¤¤º¤ì¤«¤Î¾ì¹ç¡¢
\fIx\fP ¤½¤Î¤â¤Î¤¬ÊÖ¤µ¤ì¤ë¡£
.\"O .SH ERRORS
.SH ¥¨¥é¡¼
.\"O No errors occur.
¥¨¥é¡¼¤ÏȯÀ¸¤·¤Ê¤¤¡£
.\"O POSIX.1-2001 documents a range error for overflows, but see NOTES.
POSIX.1-2001 ¤Ë¤Ï¥ª¡¼¥Ð¡¼¥Õ¥í¡¼¤Ç¤ÎÈÏ°Ï¥¨¥é¡¼ (range error) ¤Î
µ­ºÜ¤¬¤¢¤ë¡£¡ÖÃí°Õ¡×¤ÎÀá¤ò»²¾È¤Î¤³¤È¡£
.\"O .SH VERSIONS
.SH ¥Ð¡¼¥¸¥ç¥ó
.\"O These functions first appeared in glibc in version 2.1.
¤³¤ì¤é¤Î´Ø¿ô¤Ï glibc ¥Ð¡¼¥¸¥ç¥ó 2.1 ¤Ç½é¤á¤ÆÅо줷¤¿¡£
.\"O .SH "CONFORMING TO"
.SH ½àµò
C99, POSIX.1-2001.
.\"O .SH NOTES
.SH Ãí°Õ
.\"O POSIX.1-2001 contains text about overflow (which might set
.\"O .I errno
.\"O to
.\"O .BR ERANGE ,
.\"O or raise an
.\"O .B FE_OVERFLOW
.\"O exception).
POSIX.1-2001 ¤Ë¤Ï¥ª¡¼¥Ð¡¼¥Õ¥í¡¼¤Ë´Ø¤¹¤ëµ­½Ò¤¬¤¢¤ê¡¢
¥ª¡¼¥Ð¡¼¥Õ¥í¡¼¤Î¾ì¹ç¤Ë¤Ï¡¢
.I errno
¤ò
.B ERANGE
¤ËÀßÄꤹ¤ë¤«¡¢
.B FE_OVERFLOW
Îã³°¤òȯÀ¸¤¹¤ë¤³¤È¤È¤µ¤ì¤Æ¤¤¤ë¡£
.\"O In practice, the result cannot overflow on any current machine,
.\"O so this error-handling stuff is just nonsense.
¼ÂºÝ¤Î¤È¤³¤í¡¢¤É¤Î¸½¹Ô¤Î¥Þ¥·¥ó¤Ç¤Ï·ë²Ì¤¬¥ª¡¼¥Ð¡¼¥Õ¥í¡¼¤òµ¯¤³¤¹¤³¤È¤Ï¤Ê¤¤¤Î¤Ç¡¢
¤³¤Î¥¨¥é¡¼½èÍý¤Ï°ÕÌ£¤¬¤Ê¤¤¡£
.\" The POSIX.1-2001 APPLICATION USAGE SECTION discusses this point.
.\"O (More precisely, overflow can happen only when the maximum value
.\"O of the exponent is smaller than the number of mantissa bits.
.\"O For the IEEE-754 standard 32-bit and 64-bit floating-point numbers
.\"O the maximum value of the exponent is 128 (respectively, 1024),
.\"O and the number of mantissa bits is 24 (respectively, 53).)
(¤è¤êÀµ³Î¤Ë¸À¤¦¤È¡¢¥ª¡¼¥Ð¡¼¥Õ¥í¡¼¤Ï»Ø¿ôÉô¤ÎºÇÂçÃͤ¬
²¾¿ôÉô¤òɽ¤¹¥Ó¥Ã¥È¤Î¿ô¤è¤ê¾®¤µ¤¤¾ì¹ç¤Ë¤·¤«µ¯¤³¤é¤Ê¤¤¡£
IEEE-754 µ¬³Ê¤Î 32 ¥Ó¥Ã¥È¤È 64 ¥Ó¥Ã¥È¤ÎÉâÆ°¾®¿ô¤Ç¤Ï¡¢
»Ø¿ôÉô¤ÎºÇÂçÃͤϤ½¤ì¤¾¤ì 128 ¤È 1024 ¤Ç¤¢¤ê¡¢
²¾¿ôÉô¤Î¥Ó¥Ã¥È¿ô¤Ï¤½¤ì¤¾¤ì 24 ¤È 53 ¤Ç¤¢¤ë¡£)

.\"O If you want to store the rounded value in an integer type,
.\"O you probably want to use one of the functions described in
.\"O .BR lround (3)
.\"O instead.
´Ý¤á¤¿ÃͤòÀ°¿ô·¿¤Ë³ÊǼ¤·¤¿¾ì¹ç¤Ë¤Ï¡¢¤ª¤½¤é¤¯¤³¤Î´Ø¿ô¤Ç¤Ï¤Ê¤¯
.BR lround (3)
¤ËºÜ¤Ã¤Æ¤¤¤ë´Ø¿ô¤Î¤É¤ì¤«¤ò»È¤¤¤¿¤¤¤Î¤À¤í¤¦¡£
.\"O .SH "SEE ALSO"
.SH ´ØÏ¢¹àÌÜ
.BR ceil (3),
.BR floor (3),
.BR lround (3),
.BR nearbyint (3),
.BR rint (3),
.BR trunc (3)