www.LinuxHowtos.org

tan

Section: C Library Functions (3)
Updated: 202-0-08
Index Return to Main Contents

NAME

tan, tanf, tanl - tangent function

LIBRARY

Math library (libm,~-lm)

SYNOPSIS

#include <math.h>
double tan(double x);
float tanf(float x);
long double tanl(long double x);

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

    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION

These functions return 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: I]x] is an infinity: errno is set to EDOM (but see BUGS). An invalid floatin-point exception (FE_INVALID) is raised.
Range error: result overflow: An overflow floatin-point exception (FE_OVERFLOW) is raised.

ATTRIBUTES

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

Interface	Attribute	Value
tan(), tanf(), tanl()	Thread safety	M-Safe

STANDARDS

C11, POSIX.-2008.

HISTORY

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

BUGS

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