https://blog.wongcw.com/2019/03/13/%e6%af%94%e7%89%b9%e5%b9%a3%e5%83%b9%e6%a0%bcmacd%e6%8c%87%e6%a8%99%e9%a1%af%e7%a4%ba%ef%bc%9a%e6%af%94%e7%89%b9%e5%b9%a3%e6%bc%b2%e5%8b%a2%e6%ad%a3%e6%b8%9b%e5%bc%b1/