How to fit a curve in excel?
[Method]
Recommended: "Excel Tutorial"
Input the experimental data into excel, it is best to use the two variables In two vertical rows. Select all the data and be careful not to select the text as well.
Click "Insert" in the menu bar, and then select the drop-down menu under "Scatter Plot".
Smooth curve:
Select the type you need from the menu. Generally, choose a scatter plot with both data points and smooth curves. You can get a smooth curve.
Polynomial fitting (linear, exponential, power, logarithmic are similar):
(1) Select data, insert, scatter plot, select With only the type of data point, you can get the data points shown in the second picture.
(2) Click a point and all data points will be selected, then right-click and select "Add Trend Line" in the pop-up menu.
(3) Here you can choose the type of curve you need to sum, such as linear, exponential, power, logarithmic, polynomial. . Select a polynomial. Then check the "Show formula" and "Show R squared" checkboxes below to get the required curves, formulas, and relative errors.
Graphic format setting:
(1) There are still some problems after generating the graph, such as no axis name, no scale, etc. Open the design in the menu and click the drop-down menu in the icon layout.
(2) You will see many layout types of icons, choose the one you need. For example, the layout selected in the figure is a common one with a title and axis names.
(3) The coordinate axis also needs to be set: click the area near the coordinate axis with the mouse, right-click, and select "Format Axis". Detailed settings can be made here.
How to use curve fitting to find formulas in excel
Select two columns of data;
Insert a scatter line chart and click the line chart;
Add a trend line and check to display the formula and R-squared value;
Select different trend/regression analysis types. The result with R-squared closest to 1 is the most credible;
Your data is intended to be The closest trend is the 4th degree polynomial y = -1807.8x4 4291.1x3 - 3576x2 1720.2x 38.569R squared=0.9999
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