Define a new fitting function
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Ilaria Pintus
on 14 May 2019
Commented: Ilaria Pintus
on 16 May 2019
Hello everyone!
I need to define a new fitting function that is not in the matlab library. I've already tried to use the "fit App" but then I wasn't able to save the function and so re-use it. Now I'm trying in this way but it doesn't work.
model_1 = fittype('a*netOD_red+b*(netOD_red)^3','independent','netOD_red','dependent','dose')
fit_model_1 = fit(netOD_red, dose, model_1)
where my X vector is "netOD_red" and my Y vector is "dose".
The function I want to use is Y= a*X+b*(X)^3
Can someone help me? Thank you
2 Comments
Steven Lord
on 14 May 2019
Can you clarify what "it doesn't work" means?
Does MATLAB throw an error? If so what is the full and exact text of the error message you receive -- all the text displayed in red?
Does MATLAB issue a warning? If so what is the full and exact text of the warning message you receive -- all the text displayed in orange?
Does MATLAB give you a different result than you expected? If so can you show us a (small) data set and the code you use to obtain the answer (the code in your original message only shows how you created the fit -- show us how you used that fit to get the numeric result) and explain what you expected?
This information may help us understand what went wrong and/or what you're trying to do.
Accepted Answer
Steven Lord
on 15 May 2019
Is your data stored as row vectors? If so, transpose them (using the .' operator) to be column vectors in your call to fit.
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