The purpose of fitting is simply two points, one is to find the law of data points, and the other is to find the needed data by using the law. For example, we get the data point corresponding to 1 2 3 4 5 6 7 8 9. We can find out what the law of nine points is by fitting and reflect it with a function. Naturally, if we want to know the corresponding value of 8.5, we only need to substitute 8.5 into the fitted function.

Generally speaking, the fitting algorithm has shortcomings, but the difficulty of fitting is not the focus of our consideration. We don't need to pay too much attention to the methods and skills of data processing, because EXCEL, MATLAB and other software have done quite well, so it is enough for us to choose appropriate parameters and methods. Therefore, using software well is the key.