### NAME

tan, tanf, tanl - tangent function

### SYNOPSIS

**#include <math.h>**

**double tan(double ***x***);**
**float tanf(float ***x***);**
**long double tanl(long double ***x***);**

Link with *-lm*.

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

**tanf**(), **tanl**(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE; or
*cc -std=c99*

### DESCRIPTION

The
**tan**() function returns the tangent of *x*, where *x* is
given in radians.

### RETURN VALUE

On success, these functions return the tangent of
*x*.

If
*x* is a NaN, a NaN is returned.

If
*x* is positive infinity or negative infinity,
a domain error occurs,
and a NaN is returned.

If the correct result would overflow,
a range error occurs,
and the functions return
**HUGE_VAL**, **HUGE_VALF**, or
**HUGE_VALL**, respectively, with the mathematically correct sign.

### ERRORS

See math_error(7) for information on how to determine whether an error has occurred when calling these functions.

The following errors can occur:

Domain error: x is an infinity
| |

An invalid floating-point exception
(FE_INVALID) is raised.
| |

Range error: result overflow | |

An overflow floating-point exception
(FE_OVERFLOW) is raised.
| |

*errno*.

### CONFORMING TO

C99, POSIX.1-2001.
The variant returning
*double* also conforms to
SVr4, 4.3BSD, C89.

### SEE ALSO

acos(3), asin(3), atan(3), atan2(3), cos(3), ctan(3), sin(3)

### COLOPHON

This page is part of release 3.23 of the Linux
*man-pages* project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.