]>
Commit | Line | Data |
---|---|---|
fea681da | 1 | .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk) |
769cb8d5 MK |
2 | .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk |
3 | .\" <mtk.manpages@gmail.com> | |
fea681da MK |
4 | .\" |
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. | |
8 | .\" | |
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. | |
c13182ef | 13 | .\" |
fea681da MK |
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15 | .\" manual page may be incorrect or out-of-date.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 | |
20 | .\" professionally. | |
c13182ef | 21 | .\" |
fea681da MK |
22 | .\" Formatted or processed versions of this manual, if unaccompanied by |
23 | .\" the source, must acknowledge the copyright and authors of this work. | |
24 | .\" | |
25 | .\" References consulted: | |
26 | .\" Linux libc source code | |
27 | .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991) | |
28 | .\" 386BSD man pages | |
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) | |
32 | .\" | |
e4723578 | 33 | .TH TAN 3 2010-09-11 "" "Linux Programmer's Manual" |
fea681da MK |
34 | .SH NAME |
35 | tan, tanf, tanl \- tangent function | |
36 | .SH SYNOPSIS | |
37 | .nf | |
38 | .B #include <math.h> | |
39 | .sp | |
40 | .BI "double tan(double " x ); | |
d39541ec | 41 | .br |
fea681da | 42 | .BI "float tanf(float " x ); |
d39541ec | 43 | .br |
fea681da MK |
44 | .BI "long double tanl(long double " x ); |
45 | .fi | |
46 | .sp | |
20c58d70 | 47 | Link with \fI\-lm\fP. |
769cb8d5 MK |
48 | .sp |
49 | .in -4n | |
50 | Feature Test Macro Requirements for glibc (see | |
51 | .BR feature_test_macros (7)): | |
52 | .in | |
53 | .sp | |
54 | .ad l | |
55 | .BR tanf (), | |
56 | .BR tanl (): | |
57 | _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE; or | |
58 | .I cc\ -std=c99 | |
59 | .ad b | |
fea681da | 60 | .SH DESCRIPTION |
60a90ecd MK |
61 | The |
62 | .BR tan () | |
63 | function returns the tangent of \fIx\fP, where \fIx\fP is | |
fea681da | 64 | given in radians. |
769cb8d5 MK |
65 | .SH RETURN VALUE |
66 | On success, these functions return the tangent of | |
67 | .IR x . | |
68 | ||
69 | If | |
70 | .I x | |
71 | is a NaN, a NaN is returned. | |
72 | ||
73 | If | |
74 | .I x | |
75 | is positive infinity or negative infinity, | |
efe294cb | 76 | a domain error occurs, |
769cb8d5 MK |
77 | and a NaN is returned. |
78 | ||
79 | If the correct result would overflow, | |
efe294cb | 80 | a range error occurs, |
769cb8d5 MK |
81 | and the functions return |
82 | .BR HUGE_VAL , | |
83 | .BR HUGE_VALF , | |
84 | or | |
85 | .BR HUGE_VALL , | |
86 | respectively, with the mathematically correct sign. | |
87 | .\" I think overflow can't occur, because the closest floating-point | |
88 | .\" representation of pi/2 is still not close enough to pi/2 to | |
89 | .\" produce a large enough value to overflow. | |
90 | .\" Testing certainly seems to bear this out. -- mtk, Jul 08 | |
91 | .\" | |
92 | .\" POSIX.1 allows an optional underflow error; | |
93 | .\" glibc 2.8 doesn't do this | |
94 | .\" POSIX.1 an optional range error for subnormal x; | |
95 | .\" glibc 2.8 doesn't do this | |
96 | .SH ERRORS | |
97 | See | |
98 | .BR math_error (7) | |
99 | for information on how to determine whether an error has occurred | |
100 | when calling these functions. | |
101 | .PP | |
102 | The following errors can occur: | |
103 | .TP | |
104 | Domain error: \fIx\fP is an infinity | |
e4723578 MK |
105 | .I errno |
106 | is set to | |
107 | .BR EDOM | |
108 | (but see BUGS). | |
769cb8d5 MK |
109 | An invalid floating-point exception |
110 | .RB ( FE_INVALID ) | |
111 | is raised. | |
112 | .TP | |
113 | Range error: result overflow | |
114 | .\" Unable to test this case, since the best approximation of | |
115 | .\" pi/2 in double precision only yields a tan() value of 1.633e16. | |
116 | .\" .I errno | |
117 | .\" is set to | |
118 | .\" .BR ERANGE . | |
119 | An overflow floating-point exception | |
120 | .RB ( FE_OVERFLOW ) | |
121 | is raised. | |
fea681da | 122 | .SH "CONFORMING TO" |
769cb8d5 MK |
123 | C99, POSIX.1-2001. |
124 | The variant returning | |
125 | .I double | |
126 | also conforms to | |
68e1685c | 127 | SVr4, 4.3BSD, C89. |
e4723578 MK |
128 | .SH BUGS |
129 | Before version 2.10, the glibc implementation did not set | |
130 | .\" http://sourceware.org/bugzilla/show_bug.cgi?id=6782 | |
131 | .I errno | |
132 | to | |
133 | .B EDOM | |
134 | when a domain error occurred. | |
fea681da MK |
135 | .SH "SEE ALSO" |
136 | .BR acos (3), | |
137 | .BR asin (3), | |
138 | .BR atan (3), | |
139 | .BR atan2 (3), | |
140 | .BR cos (3), | |
36268806 | 141 | .BR ctan (3), |
fea681da | 142 | .BR sin (3) |