1 .\" Copyright 2004 Andries Brouwer <aeb@cwi.nl>.
2 .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
3 .\" <mtk.manpages@gmail.com>
5 .\" Permission is granted to make and distribute verbatim copies of this
6 .\" manual provided the copyright notice and this permission notice are
7 .\" preserved on all copies.
9 .\" Permission is granted to copy and distribute modified versions of this
10 .\" manual under the conditions for verbatim copying, provided that the
11 .\" entire resulting derived work is distributed under the terms of a
12 .\" permission notice identical to this one.
14 .\" Since the Linux kernel and libraries are constantly changing, this
15 .\" manual page may be incorrect or out-of-date. The author(s) assume no
16 .\" responsibility for errors or omissions, or for damages resulting from
17 .\" the use of the information contained herein. The author(s) may not
18 .\" have taken the same level of care in the production of this manual,
19 .\" which is licensed free of charge, as they might when working
22 .\" Formatted or processed versions of this manual, if unaccompanied by
23 .\" the source, must acknowledge the copyright and authors of this work.
25 .\" Inspired by a page by Walter Harms created 2002-08-10
27 .\" Japanese Version Copyright (c) 2005 Yuichi SATO
28 .\" all rights reserved.
29 .\" Translated Sat Jan 29 06:47:42 JST 2005
30 .\" by Yuichi SATO <ysato444@yahoo.co.jp>
31 .\" Updated 2008-09-16, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>
33 .\"WORD: exponent »Ø¿ôÉô
35 .\"WORD: subnormal ÈóÀµµ¬²½¤Î
37 .TH LOGB 3 2010-09-20 "" "Linux Programmer's Manual"
39 logb, logbf, logbl \- ÉâÆ°¾®¿ôÅÀ¿ô¤Î»Ø¿ô¤ò¼èÆÀ¤¹¤ë
43 .BI "double logb(double " x );
45 .BI "float logbf(float " x );
47 .BI "long double logbl(long double " x );
49 \fI\-lm\fP ¤Ç¥ê¥ó¥¯¤¹¤ë¡£
52 glibc ¸þ¤±¤Îµ¡Ç½¸¡ºº¥Þ¥¯¥í¤ÎÍ×·ï
53 .RB ( feature_test_macros (7)
60 _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 500 ||
61 _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED || _ISOC99_SOURCE ||
62 _POSIX_C_SOURCE\ >=\ 200112L;
71 _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
72 _POSIX_C_SOURCE\ >=\ 200112L;
81 ¤ÎÉâÆ°¾®¿ôÅÀ¤ÎÆâÉôɽ¸½¤«¤é»Ø¿ôÉô¤òÃê½Ð¤·¡¢ÉâÆ°¾®¿ôÅÀ¿ôÃͤȤ·¤ÆÊÖ¤¹¡£
83 ¤ÇÄêµÁ¤µ¤ì¤Æ¤¤¤ëÀ°¿ôÄê¿ô
85 ¤Ï¡¢¥·¥¹¥Æ¥à¤ÎÉâÆ°¾®¿ôÅÀɽ¸½¤Ç»ÈÍѤµ¤ì¤Æ¤¤¤ë´ð¿ô¤òɽ¤¹¡£
90 .BI floor(log2( x ))\fR
91 ¤ÈÅù¤·¤¤¤¬¡¢¸å¼Ô¤ÎÊý¤¬¤¿¤Ö¤ó¹â®¤Ç¤¢¤ë¡£
98 ¤¬Àµµ¬²½¤µ¤ì¤¿¾ì¹ç¤Î»Ø¿ô¤òÊÖ¤¹¡£
100 À®¸ù¤¹¤ë¤È¡¢¤³¤ì¤é¤Î´Ø¿ô¤Ï
105 ¤¬ NaN ¤Î¾ì¹ç¡¢NaN ¤¬ÊÖ¤µ¤ì¤ë¡£
108 ¤¬ 0 ¤Î¾ì¹ç¡¢¶Ë¥¨¥é¡¼ (pole error) ¤¬È¯À¸¤·¡¢
116 ¤¬Éé¤Î̵¸ÂÂ礫Àµ¤Î̵¸ÂÂç¤Î¾ì¹ç¡¢Àµ¤Î̵¸ÂÂ礬ÊÖ¤µ¤ì¤ë¡£
118 .\" ¤³¤ì¤é¤Î´Ø¿ô¤Ï°ú¤¿ô¤Î»Ø¿ôÉô¤òÊÖ¤¹¡£
120 ¤³¤ì¤é¤Î´Ø¿ô¤ò¸Æ¤Ó½Ð¤·¤¿ºÝ¤Ë¥¨¥é¡¼¤¬È¯À¸¤·¤¿¤«¤ÎȽÄêÊýË¡¤Ë¤Ä¤¤¤Æ¤Î¾ðÊó¤Ï
124 °Ê²¼¤Î¥¨¥é¡¼¤¬È¯À¸¤¹¤ë²ÄǽÀ¤¬¤¢¤ë¡£
126 ¶Ë¥¨¥é¡¼ (pole error): \fIx\fP ¤¬ 0 ¤Ç¤¢¤ë
130 0 ¤Ë¤è¤ë½ü»» (divide-by-zero) ÉâÆ°¾®¿ôÅÀÎã³°
137 .\" FIXME . Is it intentional that these functions do not set errno?
138 .\" log(), log2(), log10() do set errno
139 .\" Bug raised: http://sources.redhat.com/bugzilla/show_bug.cgi?id=6793
143 .\" ´Ø¿ô¤Ï 4.3BSD ¤ÇƳÆþ¤µ¤ì¤¿¡£
144 .\" 4.3BSD ¥Þ¥Ë¥å¥¢¥ë¤Î IEEE.3 ¤ò»²¾È¤¹¤ë¤³¤È¡£