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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16 | .\" manual page may be incorrect or out-of-date.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 | .\" | |
4b8c67d9 | 35 | .TH ATAN 3 2017-09-15 "" "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> | |
68e4db0a | 41 | .PP |
fea681da | 42 | .BI "double atan(double " x ); |
c13182ef | 43 | .BI "float atanf(float " x ); |
fea681da | 44 | .BI "long double atanl( long double " x ); |
68e4db0a | 45 | .PP |
fea681da | 46 | .fi |
20c58d70 | 47 | Link with \fI\-lm\fP. |
68e4db0a | 48 | .PP |
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49 | .in -4n |
50 | Feature Test Macro Requirements for glibc (see | |
51 | .BR feature_test_macros (7)): | |
52 | .in | |
68e4db0a | 53 | .PP |
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54 | .ad l |
55 | .BR atanf (), | |
56 | .BR atanl (): | |
36e93b81 | 57 | .RS 4 |
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58 | _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L |
59 | || /* Since glibc 2.19: */ _DEFAULT_SOURCE | |
60 | || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE | |
36e93b81 | 61 | .RE |
9732b053 | 62 | .ad b |
fea681da | 63 | .SH DESCRIPTION |
5600f73a | 64 | These functions calculate the principal value of the arc tangent of |
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65 | .IR x ; |
66 | that is the value whose tangent is | |
67 | .IR x . | |
47297adb | 68 | .SH RETURN VALUE |
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69 | On success, these functions return the principal value of the arc tangent of |
70 | .IR x | |
be4c136a | 71 | in radians; the return value is in the range [\-pi/2,\ pi/2]. |
847e0d88 | 72 | .PP |
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73 | If |
74 | .I x | |
75 | is a NaN, a NaN is returned. | |
847e0d88 | 76 | .PP |
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77 | If |
78 | .I x | |
79 | is +0 (\-0), | |
80 | +0 (\-0) is returned. | |
847e0d88 | 81 | .PP |
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82 | If |
83 | .I x | |
84 | is positive infinity (negative infinity), +pi/2 (\-pi/2) is returned. | |
85 | .\" | |
86 | .\" POSIX.1-2001 documents an optional range error for subnormal x; | |
87 | .\" glibc 2.8 does not do this. | |
88 | .SH ERRORS | |
89 | No errors occur. | |
941daa87 | 90 | .SH ATTRIBUTES |
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91 | For an explanation of the terms used in this section, see |
92 | .BR attributes (7). | |
93 | .TS | |
94 | allbox; | |
95 | lbw24 lb lb | |
96 | l l l. | |
97 | Interface Attribute Value | |
98 | T{ | |
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99 | .BR atan (), |
100 | .BR atanf (), | |
941daa87 | 101 | .BR atanl () |
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102 | T} Thread safety MT-Safe |
103 | .TE | |
47297adb | 104 | .SH CONFORMING TO |
9a74e018 | 105 | C99, POSIX.1-2001, POSIX.1-2008. |
847e0d88 | 106 | .PP |
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107 | The variant returning |
108 | .I double | |
109 | also conforms to | |
110 | SVr4, 4.3BSD, C89. | |
47297adb | 111 | .SH SEE ALSO |
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112 | .BR acos (3), |
113 | .BR asin (3), | |
114 | .BR atan2 (3), | |
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115 | .BR carg (3), |
116 | .BR catan (3), | |
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117 | .BR cos (3), |
118 | .BR sin (3), | |
119 | .BR tan (3) |