说明：  根据已知数据的权重对数据进行拟合，若不能给出数据的权重就默认为数据权重为1.这种拟合 方法是根据最小二乘进行的。
(The basis of known data on the weight of the data fitting, if the data should not give the weight for data on the default weight is 1. This method is based on least-squares fitting carried out.)