问题
During an experiment i registered several points. Thereafter I approximated them with 9th order polynomial. I need to find the absolute error of the measurements and the approximated function on y axis. Any idea?
*edit:
y = [0.006332 0.04056 0.11813 0.1776723 0.23840 0.29827 0.358396...
0.418149 0.4786 0.478154 0.538114 0.53862 0.598954 0.659804...
0.720267 0.781026 0.8412 0.901548 0.962022 1.022567 1.083291...
1.143653 1.20449 1.14398 1.02273 0.962285 0.90203 0.841474...
0.780881 0.720346 0.659896 0.579599 0.539505 0.478662 0.418963...
0.35859 0.299039 0.238886 0.179108 0.118999 0.058841 0.006249...
0.06189];
x2 = linspace (1,43,43);
x2 = x2';
y = y';
f = fit(x2,y,'poly9');
figure()
plot(f,x2,y)
回答1:
This will do it:
y_fit = f(x2);
error = y - y_fit;
hold on
plot(x2, error)
% Several popular error norms:
norm(error, 1)
norm(error, 2)
norm(error, Inf)
Like y, the variable error is a vector. If you want to reduce this vector to a single number, you can use one the norms. See this for more on error norms.
来源：https://stackoverflow.com/questions/30548583/finding-absolute-error-of-approximated-function-matlab