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: 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).

       ┌───────────────────────────────────────────────────────────────┬───────────────┬─────────┐
       │Interface                                                      │ Attribute     │ Value   │
       ├───────────────────────────────────────────────────────────────┼───────────────┼─────────┤
       │tan(), tanf(), tanl()                                          │ Thread safety │ MT-Safe │
       └───────────────────────────────────────────────────────────────┴───────────────┴─────────┘

STANDARDS

       C11, POSIX.1-2008.

HISTORY

       C99, POSIX.1-2001.

       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.

SEE ALSO

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