Simone问题补充说明：看到拟合里这么一句话"y=span{1,x,x2}"，用最小二乘法拟合。这是什么函数？是二次多项式么？
span::span构造函数
span(cons护响学供律家距t marker_series& _Series,
_In_ LPCTSTR _Format,
...
);
span(
const mark晶造制每那力基触肥律额er_series& _Series,
marker_importance _Importance,
_In_ LPCTSTR _Format,
...
);
span(
const marker_series& _Series,
int _要停距Category,
_In_ LPCTSTR _Format,
...
);
span(
const marker_series& _Series,
marke挥曾r_importanc充完道点告除体慢怀e _Importance三富花,
int _Category,
_In_ LPCTSTR _Format,
...
);
