Linux manual pages Section 3  

Name

cos, cosf, cosl — cosine function

Synopsis

#include <math.h>
double cos( double x);
 
float cosf( float x);
 
long double cosl( long double x);
 
[Note] Note
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
[Note] Note

Link with −lm.

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

CONFORMING TO

C99, POSIX.1-2001, POSIX.1-2008.

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

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

COLOPHON

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