NAME

       cos, cosf, cosl - cosine function

LIBRARY

       Math library (libm, -lm)

SYNOPSIS

       #include <math.h>

       double cos(double x);
       float cosf(float x);
       long double cosl(long double x);

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

       cosf(), cosl():
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION

       These functions return the cosine of x, where x is given in radians.

RETURN VALUE

       On success, these functions return the cosine 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.

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.

ATTRIBUTES

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

       ┌───────────────────────────────────────────────────────────────┬───────────────┬─────────┐
       │Interface                                                      │ Attribute     │ Value   │
       ├───────────────────────────────────────────────────────────────┼───────────────┼─────────┤
       │cos(), cosf(), cosl()                                          │ Thread safety │ MT-Safe │
       └───────────────────────────────────────────────────────────────┴───────────────┴─────────┘

STANDARDS

       C11, POSIX.1-2008.

HISTORY

       C89, POSIX.1-2001.

       The variant returning double also conforms to SVr4, 4.3BSD.

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), ccos(3), sin(3), sincos(3), tan(3)