Answering your main question: beta0 is the initial guess at the coefficients of the fit. In your case, MATLAB is expecting a vector of length 10, because you have 10 parameters to fit.
There are lots of problems with both your MATLAB syntax, and how you are trying to fit your curves. In the code below, I have fixed the syntax problems, by
- fixing the beta0 problem you asked about
- creating separate tables for each fit
- storing the resulting models in a cell array
But, I did not try to fix the equation you are trying to fit to.
load Data
x = (1:size(Data,2))';
% Define the fitting function
Sig = @(p,x) p(4)./(1 + exp(-p(1).*x + p(7))) + p(5)./(1 + exp(-p(2).*x + p(8))) + p(6)./(1 + exp(-p(3).*x + p(9))) + p(10);
% Initial guess of coefficients
beta0 = ones(1,10);
for k = 1:size(Data,1)
% Put the data for this curve into a table
y = Data(k,:)';
tbl = table(x,y);
% Fit the model
mdl{k} = fitnlm(tbl,Sig,beta0);
% Plot the fit against the data
figure
hold on
plot(x,Data(k,:),'o')
plot(x,predict(mdl{k},x))
end
