function
<cmath> <ctgmath>

# cos

```double cos (double x);
```
```     double cos  (double x);
float cosf (float x);
long double cosl (long double x);
```
```     double cos (double x);
float cos (float x);
long double cos (long double x);
```
```     double cos (double x);
float cos (float x);
long double cos (long double x);
double cos (T x);           // additional overloads for integral types```
Compute cosine
Returns the cosine of an angle of x radians.

Header <tgmath.h> provides a type-generic macro version of this function.
This function is overloaded in `<complex>` and `<valarray>` (see complex cos and valarray cos).
Additional overloads are provided in this header (`<cmath>`) for the integral types: These overloads effectively cast x to a `double` before calculations (defined for T being any integral type).

This function is also overloaded in `<complex>` and `<valarray>` (see complex cos and valarray cos).

### Parameters

x
Value representing an angle expressed in radians.
One radian is equivalent to `180/PI` degrees.

### Return Value

Cosine of x radians.

### Example

 ``1234567891011121314`` ``````/* cos example */ #include /* printf */ #include /* cos */ #define PI 3.14159265 int main () { double param, result; param = 60.0; result = cos ( param * PI / 180.0 ); printf ("The cosine of %f degrees is %f.\n", param, result ); return 0; }``````

Output:
 ``` The cosine of 60.000000 degrees is 0.500000. ```