# TAN

NAME

SYNOPSIS

DESCRIPTION

RETURN VALUE

ERRORS

ATTRIBUTES

CONFORMING TO

BUGS

SEE ALSO

COLOPHON

## 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 ||
_POSIX_C_SOURCE >= 200112L;

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

*errno* is set to
**EDOM** (but see BUGS). An invalid floating-point
exception (**FE_INVALID**) is raised.

Range error: result
overflow

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

## ATTRIBUTES

For an
explanation of the terms used in this section, see
**attributes**(7).

## CONFORMING TO

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

## BUGS

Before version
2.10, the glibc implementation did not set *errno* to
**EDOM** when a domain error occurred.

## SEE ALSO

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

## COLOPHON

This page is
part of release 3.53 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/.