public function setAngle($min, $max = null) {

		if(false === ('-' . intval($min) == '-' . $min)) {
			return trigger_error(sprintf('Argument 1 passed to %s() must be of the type integer, "%s" given', __METHOD__, gettype($min)), E_USER_ERROR);
		}

		if(null !== $max && false === ('-' . intval($max) == '-' . $max)) {
			return trigger_error(sprintf('Argument 2 passed to %s() must be of the type integer, "%s" given', __METHOD__, gettype($max)), E_USER_ERROR);
		}

		$this -> angle = ['min' => $min, 'max' => ($max !== null ? $max : $min)];

		return $this;
	}