皮尔逊三型曲线,水文研究，曲线拟合，都可以看代码学习-this is the code of persion3

拟合p3曲线，获得参数；根据参数绘制p3曲线；插值获取不同频率的流量数据，(Fitting the P3 curve to get the parameters, drawing the P3 curve according to the parameters, and interpolating the flow data of different frequencies.)