function rad2deg( x ) {
	return x * CONST_180_DIV_PI;
}
Converts an angle from radians to degrees.

@param {number} x - angle in radians
@returns {number} angle in degrees

@example
var d = rad2deg( 3.141592653589793/2.0 );
// returns 90.0

@example
var d = rad2deg( -3.141592653589793/4.0 );
// returns -45.0

@example
var d = rad2deg( NaN );
// returns NaN