[Image]1. Introduction In previous articles, we discussed data interpolation. Today, I will write about its sister topic—data fitting. The characteristic of data interpolation is that the interpolation function strictly passes through all interpolation nodes, while data fitting only requires the fitting function to reasonably reflect the trend of the curve, without the necessity of passing through all data points. The purpose of data interpolation is internal prediction, meaning that the independent variable of the point to be predicted falls within the range of independent variable values at the interpolation nodes. Data…