MATLAB Fundamentals>Common Data Analysis Techniques>Polynomial Fitting>Centering and Scaling

数据导入

This code sets up the activity.

yr = 2000:2007
penguins = [5.49  7.03  7.73  7.70  9.29  9.21  11.89  10.85]

附加练习

How does the model look? Plot the data (penguins as a function of yr) as points, then overlay a plot of the model (penguinFit).

Note that you ignored some inputs and outputs for polyfit and polyval. These provide statistical information about the fit, allowing you to do more sophisticated analysis. For example, you can obtain standard error estimates of the predicted fit values.

[c,S,sc] = polyfit(yr,penguins,3)
[penguinFit,serr] = polyval(c,yr,S,sc)

With these, you can calculate a 95% prediction interval.

predInt = penguinFit + 2*[1;-1]*serr
plot(yr,penguins,"o",...
    yr,penguinFit,yr,predInt,"r--")

结果