1 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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15 .\" manual page may be incorrect or out-of-date.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 .\" References consulted:
26 .\" Linux libc source code
27 .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
29 .\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
30 .\" Modified 2002-07-27 by Walter Harms
31 .\" (walter.harms@informatik.uni-oldenburg.de)
33 .\" Japanese Version Copyright (c) 1996 Kenji Kajiwara and Kentaro Ogawa
34 .\" all rights reserved.
35 .\" Translated Sat, 13 Jul 1996 17:50:45 JST
36 .\" by Kenji Kajiwara and Kentaro Ogawa
37 .\" Proof Reading: Takashi Yoshino
38 .\" Updated Tue Aug 5 23:16:48 JST 2003
39 .\" by Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>
40 .\" Updated 2008-09-15, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>
42 .TH ATAN2 3 2010-09-20 "" "Linux Programmer's Manual"
45 .\"O atan2, atan2f, atan2l \- arc tangent function of two variables
46 atan2, atan2f, atan2l \- 二つの変数に対する逆正接(arc tangent)関数
52 .BI "double atan2(double " y ", double " x );
53 .BI "float atan2f(float " y ", float " x );
54 .BI "long double atan2l(long double " y ", long double " x );
57 .\"O Link with \fI\-lm\fP.
61 .\"O Feature Test Macro Requirements for glibc (see
62 .\"O .BR feature_test_macros (7)):
64 .RB ( feature_test_macros (7)
72 _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
73 _POSIX_C_SOURCE\ >=\ 200112L;
83 .\"O function calculates the principal value of the arc tangent of
85 .\"O using the signs of the two arguments to determine
86 .\"O the quadrant of the result.
90 の逆正接 (arg tangent) の主値を計算する。
91 二つの引き数の符号は結果の象限を決定するために使われる。
92 .\"O .SH "RETURN VALUE"
94 .\"O On success, these functions return the principal value of the arc tangent of
96 .\"O in radians; the return value is in the range [\-pi,\ pi].
100 返り値は [\-pi,\ pi] の範囲となる。
106 .\"O is less than 0, +pi (\-pi) is returned.
110 が 0 未満の場合、+pi (\-pi) が返される。
116 .\"O is greater than 0, +0 (\-0) is returned.
120 が 0 より大きい場合、+0 (\-0) が返される。
124 .\"O is less than 0 and
126 .\"O is +0 or \-0, \-pi/2 is returned.
130 が +0 か \-0 の場合、\-pi/2 が返される。
134 .\"O is greater than 0 and
136 .\"O is +0 or \-0, pi/2 is returned.
140 が +0 か \-0 の場合、pi/2 が返される。
145 .\" is 0, a pole error shall not occur.
151 .\"O is NaN, a NaN is returned.
155 のいずかが NaN の場合、NaN が返される。
158 .\" If the result underflows, a range error may occur and
160 .\" should be returned.
166 .\"O is \-0, +pi (\-pi) is returned.
170 が \-0 の場合、+pi (\-pi) が返される。
176 .\"O is +0, +0 (\-0) is returned.
180 が +0 の場合、+0 (\-0) が返される。
184 .\"O is a finite value greater (less) than 0, and
186 .\"O is negative infinity, +pi (\-pi) is returned.
190 が負の無限大の場合、+pi (\-pi) が返される。
194 .\"O is a finite value greater (less) than 0, and
196 .\"O is positive infinity, +0 (\-0) is returned.
200 が正の無限大の場合、+0 (\-0) が返される。
204 .\"O is positive infinity (negative infinity), and
207 .\"O pi/2 (\-pi/2) is returned.
211 が有限値の場合、pi/2 (\-pi/2) が返される。
215 .\"O is positive infinity (negative infinity) and
217 .\"O is negative infinity, +3*pi/4 (\-3*pi/4) is returned.
221 が負の無限大の場合、+3*pi/4 (\-3*pi/4) が返される。
225 .\"O is positive infinity (negative infinity) and
227 .\"O is positive infinity, +pi/4 (\-pi/4) is returned.
231 が正の無限大の場合、+pi/4 (\-pi/4) が返される。
234 .\" If both arguments are 0, a domain error shall not occur.
237 .\"O No errors occur.
239 .\" POSIX.1 documents an optional underflow error
240 .\" glibc 2.8 does not do this.
241 .\"O .SH "CONFORMING TO"
244 .\"O The variant returning
246 .\"O also conforms to
247 .\"O SVr4, 4.3BSD, C89.
249 版の関数は SVr4, 4.3BSD, C89 にも準拠している。