https://wenku.baidu.com/view/49828d28647d27284b73510f.html
idocdown-v3.2.8 文档下载
https://c-t.work/s/f3c7442b6eae4b
// 椭圆圆周公式
https://blog.youkuaiyun.com/chenlu5201314/article/details/100023943
椭圆一般方程求解椭圆标准方程参数
https://blog.youkuaiyun.com/easecode/article/details/22610761