Fitting the curve problem
3 visualizzazioni (ultimi 30 giorni)
Mostra commenti meno recenti
I try to fit an s-shape curve with the function that I define. Actually I get a not-so-bad fitting by setting a more appropriate boundary and starting point. One remaining question is that although the fit is better, the parameters' range is still big. Anyone has any advice for this? Attached file is the data file for Ch4.
Final_time=10;
recordLength=size(Ch4);
recordLength=recordLength(1);
Time=[linspace(0,Final_time*1000,recordLength)]';
Ch4_mV=Ch4.*1000;
[pks,locs]=findpeaks(Ch4_mV,'MinPeakProminence',30);
for j=3
duration_fit=Time(locs(j)-6:locs(j)+10);
y_duration_fit=Ch4_mV(locs(j)-6:locs(j)+10);
FitFunction=@(a,b,A,B,F,e,x)F.*(b.*A-(x-a).*B)./((x-a).^2+b^2)+e;
options=fitoptions('Method','NonlinearLeastSquares','Upper',[Time(locs(j)+50) Time(8)-Time(1) 1 1 pks(j)+10 0],'Lower',[Time(locs(j)-50) 0 -1 -1 pks(j)-10 -15],'StartPoint',[Time(locs(j)),1,1,Time(locs(j)+5)-Time(locs(j)-2),pks(j),1]);
[fitcurve,gof]=fit(duration_fit,y_duration_fit,FitFunction,options)
plot(fitcurve,duration_fit,y_duration_fit);
end
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/921169/image.png)
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/921174/image.png)
4 Commenti
Sam Chak
il 10 Mar 2022
Looks like the Stribeck friction model. No harm trying to fit with the suggested model, but you need to shift the center to approximately
.
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/921264/image.png)
Risposte (0)
Vedere anche
Categorie
Scopri di più su Get Started with Curve Fitting Toolbox in Help Center e File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!