Linux Programmer’s Manual
cos, cosf, cosl − cosine function
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(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE;
or cc -std=c99
The cos() function returns 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
The following errors can occur:
Domain error: x is an infinity
An invalid floating-point exception (FE_INVALID) is raised.
These functions do not set errno.
C99, POSIX.1-2001. The variant returning double also conforms to SVr4, 4.3BSD.
acos(3), asin(3), atan(3), atan2(3), ccos(3), sin(3), sincos(3), tan(3)
This page is part of release 3.24 of the Linux man-pages project. A description of the project, and informa-
tion about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.