Fitting the curve problem
3 visualizaciones (últimos 30 días)
Mostrar comentarios más antiguos
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 comentarios
Sam Chak
el 10 de Mzo. de 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)
Respuestas (0)
Ver también
Categorías
Más información sobre Get Started with Curve Fitting Toolbox en Help Center y File Exchange.
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!