cos - cosine function
#include <math.h> double cos(double x);
The cos() function computes the cosine of x, measured in radians.
An application wishing to check for error situations should set errno to 0 before calling cos(). If errno is non-zero on return, or the returned value is NaN, an error has occurred.
Upon successful completion, cos() returns the cosine of x.
If x is NaN, NaN is returned and errno may be set to [EDOM].
If x is ±Inf, either 0 is returned and errno is set to [EDOM], or NaN is returned and errno may be set to [EDOM].
If the result underflows, 0 is returned and errno may be set to [ERANGE].
The cos() function may fail if:
- The value of x is NaN or x is ±Inf.
- The result underflows.
No other errors will occur.
The cos() function may lose accuracy when its argument is far from 0.
acos(), isnan(), sin(), tan(), <math.h>.
Derived from Issue 1 of the SVID.