How to extract coefficients from from curve fitting tool?

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

[sebastian ruiz]

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

Answer 1

[John D'Errico]

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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