1. For the curve fitting of the function of two variables (x, y), we can get the trend line equation from the scatter chart with smooth lines in EXCEL, which is the curve fitting function. The specific process is as follows: (1) Select the data of cells A and B; (2) Click "Insert"-select a scatter plot with smooth lines; (3) Right-click the graph and click Add Trend Line-Select Regression Analysis Type-Indicator-Select Display Formula to display R-squared value. This completes the curve fitting.

2, for multivariate (x 1, x2, x3. . . ) function fitting, you can use EXCEL's own data analysis module for linear function fitting. The specific process is as follows: (1) Set the sum of the relationships between A and B, C, D and E (for example, X13, x2^3, x4^3, X12, x2^2, x3^2, X4). (2) Select data-select data analysis-select regression-confirm; (3) Click the Y value input area and select $ A $ 2:$ A $ 37；; Click the X value input area and select $ f $ 2:$ m $ 37；; (4) Select "95% confidence" and confirm; (5) Get the data of regression statistics, such as r 2, coefficient of fitting function, analysis of variance, etc. In this way, the multivariate function fitting is completed.