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fea681da | 1 | .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk) |
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2 | .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk |
3 | .\" <mtk.manpages@gmail.com> | |
fea681da | 4 | .\" |
93015253 | 5 | .\" %%%LICENSE_START(VERBATIM) |
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6 | .\" Permission is granted to make and distribute verbatim copies of this |
7 | .\" manual provided the copyright notice and this permission notice are | |
8 | .\" preserved on all copies. | |
9 | .\" | |
10 | .\" Permission is granted to copy and distribute modified versions of this | |
11 | .\" manual under the conditions for verbatim copying, provided that the | |
12 | .\" entire resulting derived work is distributed under the terms of a | |
13 | .\" permission notice identical to this one. | |
c13182ef | 14 | .\" |
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15 | .\" Since the Linux kernel and libraries are constantly changing, this |
16 | .\" manual page may be incorrect or out-of-date. The author(s) assume no | |
17 | .\" responsibility for errors or omissions, or for damages resulting from | |
18 | .\" the use of the information contained herein. The author(s) may not | |
19 | .\" have taken the same level of care in the production of this manual, | |
20 | .\" which is licensed free of charge, as they might when working | |
21 | .\" professionally. | |
c13182ef | 22 | .\" |
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23 | .\" Formatted or processed versions of this manual, if unaccompanied by |
24 | .\" the source, must acknowledge the copyright and authors of this work. | |
4b72fb64 | 25 | .\" %%%LICENSE_END |
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26 | .\" |
27 | .\" References consulted: | |
28 | .\" Linux libc source code | |
29 | .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991) | |
30 | .\" 386BSD man pages | |
31 | .\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu) | |
32 | .\" Modified 2002-07-27 by Walter Harms | |
33 | .\" (walter.harms@informatik.uni-oldenburg.de) | |
34 | .\" | |
97986708 | 35 | .TH ATAN 3 2016-03-15 "" "Linux Programmer's Manual" |
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36 | .SH NAME |
37 | atan, atanf, atanl \- arc tangent function | |
38 | .SH SYNOPSIS | |
39 | .nf | |
40 | .B #include <math.h> | |
41 | .sp | |
42 | .BI "double atan(double " x ); | |
d39541ec | 43 | .br |
c13182ef | 44 | .BI "float atanf(float " x ); |
d39541ec | 45 | .br |
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46 | .BI "long double atanl( long double " x ); |
47 | .sp | |
48 | .fi | |
20c58d70 | 49 | Link with \fI\-lm\fP. |
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50 | .sp |
51 | .in -4n | |
52 | Feature Test Macro Requirements for glibc (see | |
53 | .BR feature_test_macros (7)): | |
54 | .in | |
55 | .sp | |
56 | .ad l | |
57 | .BR atanf (), | |
58 | .BR atanl (): | |
36e93b81 | 59 | .RS 4 |
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60 | _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L |
61 | || /* Since glibc 2.19: */ _DEFAULT_SOURCE | |
62 | || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE | |
36e93b81 | 63 | .RE |
9732b053 | 64 | .ad b |
fea681da | 65 | .SH DESCRIPTION |
5600f73a | 66 | These functions calculate the principal value of the arc tangent of |
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67 | .IR x ; |
68 | that is the value whose tangent is | |
69 | .IR x . | |
47297adb | 70 | .SH RETURN VALUE |
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71 | On success, these functions return the principal value of the arc tangent of |
72 | .IR x | |
be4c136a | 73 | in radians; the return value is in the range [\-pi/2,\ pi/2]. |
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74 | |
75 | If | |
76 | .I x | |
77 | is a NaN, a NaN is returned. | |
78 | ||
79 | If | |
80 | .I x | |
81 | is +0 (\-0), | |
82 | +0 (\-0) is returned. | |
83 | ||
84 | If | |
85 | .I x | |
86 | is positive infinity (negative infinity), +pi/2 (\-pi/2) is returned. | |
87 | .\" | |
88 | .\" POSIX.1-2001 documents an optional range error for subnormal x; | |
89 | .\" glibc 2.8 does not do this. | |
90 | .SH ERRORS | |
91 | No errors occur. | |
941daa87 | 92 | .SH ATTRIBUTES |
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93 | For an explanation of the terms used in this section, see |
94 | .BR attributes (7). | |
95 | .TS | |
96 | allbox; | |
97 | lbw24 lb lb | |
98 | l l l. | |
99 | Interface Attribute Value | |
100 | T{ | |
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101 | .BR atan (), |
102 | .BR atanf (), | |
941daa87 | 103 | .BR atanl () |
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104 | T} Thread safety MT-Safe |
105 | .TE | |
47297adb | 106 | .SH CONFORMING TO |
9a74e018 | 107 | C99, POSIX.1-2001, POSIX.1-2008. |
e05e3635 | 108 | |
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109 | The variant returning |
110 | .I double | |
111 | also conforms to | |
112 | SVr4, 4.3BSD, C89. | |
47297adb | 113 | .SH SEE ALSO |
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114 | .BR acos (3), |
115 | .BR asin (3), | |
116 | .BR atan2 (3), | |
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117 | .BR carg (3), |
118 | .BR catan (3), | |
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119 | .BR cos (3), |
120 | .BR sin (3), | |
121 | .BR tan (3) |