##### Synopsis

    #include <math.h>
    float cosf(float x);

##### Description

cosf returns the radian circular cosine of x.

##### Fast math library behavior

If |x| > 10^9, errno is set to EDOM and cosf returns HUGE_VALF.

##### IEC 60559 math library behavior

If x is NaN, cosf returns x.
If |x| is ∞, cosf returns NaN with invalid signal .

##### Portability

cosf conforms to ISO/IEC 9899:1990 (C90) and ISO/IEC 9899:1999 (C99).