NAME

cos - cosine function

 SYNOPSIS

#include <math.h>

double cos(double x);

 DESCRIPTION

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.

 RETURN VALUE

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].

 ERRORS

The cos() function may fail if:

[EDOM]

The value of x is NaN or x is ±Inf.

[ERANGE]

The result underflows.

No other errors will occur.

 EXAMPLES

None.

 APPLICATION USAGE

The cos() function may lose accuracy when its argument is far from 0.

 FUTURE DIRECTIONS

None.

 SEE ALSO

acos(), isnan(), sin(), tan(), <math.h>.

DERIVATION

Derived from Issue 1 of the SVID.