How to extract coefficients from from curve fitting tool?

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Benjamin
Benjamin 2020-12-10
评论： sebastian ruiz 2021-12-20
Hello everyone,
I used Curve Fitting Tool in MATLAB and fitted a curve to some data points. Then generate the code and used it as a function as a part of my program. However, when the results show up, they are not stored in a cell or struct to be used later in the program. I am especifically refering to the model fit coefficients which is the output of the curve fitting function.
Does anybody know a way to extract the model fit coefficients.
Here I attached the program. By running the program the model fit (coefficients a and i) will be shown (as picture bellow), but not stored/saved in the workspace.
I appreciate your responses in advance
  1 个评论
sebastian ruiz
sebastian ruiz 2021-12-20
Greetings,
In case it is still good for you.
The output from a cftool will be a *.sfit
so for example,
fit001.sfit % your output and you want the goodness RMSEs
then while on that folder,
for i = 1:length
fit001_rmse(:,i) = fit001.AllFitdevsAndConfigs{i,1}.Fitdev.Goodness.rmse;
end

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John D'Errico
John D'Errico 2020-12-10
编辑：John D'Errico 2020-12-10
Ran in:
Simply enough. In fact, they ARE stored in the workspace. They are just not returned as separate variables. And that is a good thing. Extracting them is trivial though.
x = rand(10,1);
y = randn(10,1);
g1 = fit(x,y,'power1')
g1 =
General model Power1: g1(x) = a*x^b Coefficients (with 95% confidence bounds): a = -0.1631 (-0.6644, 0.3382) b = -0.4213 (-2.33, 1.487)
g1.a
ans = -0.1631
g1.b
ans = -0.4213
Or, if you wish to extract them as a vector of coefficients, just do
format long g
coeffvalues(g1)
ans = 1×2
-0.163113290762181 -0.421325379677972
●

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