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COS(3) Linux Programmer's Manual COS(3)

cos, cosf, cosl - cosine function

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

Link with -lm.


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 versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

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

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.

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.

For an explanation of the terms used in this section, see attributes(7).
Interface Attribute Value
cos (), cosf (), cosl () Thread safety MT-Safe

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

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

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

acos(3), asin(3), atan(3), atan2(3), ccos(3), sin(3), sincos(3), tan(3)

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2017-09-15