Least-squares fitting of data
About this calculator
This applet allows the user to enter pairs of data -- x, an independent variable; and y, the dependent variable -- and then generates an equation to describe the best "fit" for that data. The applet can generate several types of best-fit equations. It can generate a linear fit, producing the standard y=mx + b equation, where m is the slope and b is the y-intercept (the value of y when x=0). It can also produce a polynomial fit, typically a more accurate equation to describe the data. A polynomial fit with a degree of 3 will produce this equation:
y = c0 + c1*x + c2*x2 +c3*x3
where c0, c1, c2, and c3 are the coefficients. These coefficients (called expansion coefficients by the applet).
Using this calculator
To use this calculator, follow this recipe:
- Select the type of fit you want. If you choose a polynomial fit, choose the degree.
- For most fits, leave "Constant" selected.
- Click on "Data". A separate window will appear, providing you with a text box. Type or copy your x-y data into the box. The data should be in pairs with a space between the x-value and the y-value. Click on the "Submit" button
- Your coefficients will appear in the output window.