| .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk) |
| .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk |
| .\" <mtk.manpages@gmail.com> |
| .\" |
| .\" %%%LICENSE_START(VERBATIM) |
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| .\" manual under the conditions for verbatim copying, provided that the |
| .\" entire resulting derived work is distributed under the terms of a |
| .\" permission notice identical to this one. |
| .\" |
| .\" Since the Linux kernel and libraries are constantly changing, this |
| .\" manual page may be incorrect or out-of-date. The author(s) assume no |
| .\" responsibility for errors or omissions, or for damages resulting from |
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| .\" References consulted: |
| .\" Linux libc source code |
| .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991) |
| .\" 386BSD man pages |
| .\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu) |
| .\" Modified 2002-07-27 by Walter Harms |
| .\" (walter.harms@informatik.uni-oldenburg.de) |
| .\" |
| .TH TAN 3 2017-09-15 "" "Linux Programmer's Manual" |
| .SH NAME |
| tan, tanf, tanl \- tangent function |
| .SH SYNOPSIS |
| .nf |
| .B #include <math.h> |
| .PP |
| .BI "double tan(double " x ); |
| .BI "float tanf(float " x ); |
| .BI "long double tanl(long double " x ); |
| .fi |
| .PP |
| Link with \fI\-lm\fP. |
| .PP |
| .in -4n |
| Feature Test Macro Requirements for glibc (see |
| .BR feature_test_macros (7)): |
| .in |
| .PP |
| .ad l |
| .BR tanf (), |
| .BR tanl (): |
| .RS 4 |
| _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L |
| || /* Since glibc 2.19: */ _DEFAULT_SOURCE |
| || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE |
| .RE |
| .ad |
| .SH DESCRIPTION |
| These functions return the tangent of |
| .IR x , |
| where |
| .I x |
| is |
| given in radians. |
| .SH RETURN VALUE |
| On success, these functions return the tangent of |
| .IR x . |
| .PP |
| If |
| .I x |
| is a NaN, a NaN is returned. |
| .PP |
| If |
| .I x |
| is positive infinity or negative infinity, |
| a domain error occurs, |
| and a NaN is returned. |
| .PP |
| If the correct result would overflow, |
| a range error occurs, |
| and the functions return |
| .BR HUGE_VAL , |
| .BR HUGE_VALF , |
| or |
| .BR HUGE_VALL , |
| respectively, with the mathematically correct sign. |
| .\" I think overflow can't occur, because the closest floating-point |
| .\" representation of pi/2 is still not close enough to pi/2 to |
| .\" produce a large enough value to overflow. |
| .\" Testing certainly seems to bear this out. -- mtk, Jul 08 |
| .\" |
| .\" POSIX.1 allows an optional underflow error; |
| .\" glibc 2.8 doesn't do this |
| .\" POSIX.1 an optional range error for subnormal x; |
| .\" glibc 2.8 doesn't do this |
| .SH ERRORS |
| See |
| .BR math_error (7) |
| for information on how to determine whether an error has occurred |
| when calling these functions. |
| .PP |
| The following errors can occur: |
| .TP |
| Domain error: \fIx\fP is an infinity |
| .I errno |
| is set to |
| .B EDOM |
| (but see BUGS). |
| An invalid floating-point exception |
| .RB ( FE_INVALID ) |
| is raised. |
| .TP |
| Range error: result overflow |
| .\" Unable to test this case, since the best approximation of |
| .\" pi/2 in double precision only yields a tan() value of 1.633e16. |
| .\" .I errno |
| .\" is set to |
| .\" .BR ERANGE . |
| An overflow floating-point exception |
| .RB ( FE_OVERFLOW ) |
| is raised. |
| .SH ATTRIBUTES |
| For an explanation of the terms used in this section, see |
| .BR attributes (7). |
| .TS |
| allbox; |
| lbw21 lb lb |
| l l l. |
| Interface Attribute Value |
| T{ |
| .BR tan (), |
| .BR tanf (), |
| .BR tanl () |
| T} Thread safety MT-Safe |
| .TE |
| .SH CONFORMING TO |
| C99, POSIX.1-2001, POSIX.1-2008. |
| .PP |
| The variant returning |
| .I double |
| also conforms to |
| SVr4, 4.3BSD, C89. |
| .SH BUGS |
| Before version 2.10, the glibc implementation did not set |
| .\" http://sourceware.org/bugzilla/show_bug.cgi?id=6782 |
| .I errno |
| to |
| .B EDOM |
| when a domain error occurred. |
| .SH SEE ALSO |
| .BR acos (3), |
| .BR asin (3), |
| .BR atan (3), |
| .BR atan2 (3), |
| .BR cos (3), |
| .BR ctan (3), |
| .BR sin (3) |