function tand( x ) {
	return addon( x );
}
Computes the tangent of an angle measured in degrees.

@private
@param {number} x - input value (in degrees)
@returns {number} tangent

@example
var v = tand( 0.0 );
// returns 0.0

@example
var v = tand( 90.0 );
// returns Infinity

@example
var v = tand( 60.0 );
// returns ~1.732

@example
var v = tand( NaN );
// returns NaN