Multiple fit displayed

[booghimen]

Hi all,

I have to fit a TGraph in 2 different rages, using 2 different functions.
The problem is that only the 2nd fit function is drawed on the canvas, but not the 1st one.
Can some one give me a suggestion?

Thanks in advance

[dastudillo]

Try using the “+” option when fitting the second, third, etc. functions, e.g.:

gr->Fit(fit1,“R”);
gr->Fit(fit2,“R+”);

[booghimen]

Thanks fot the sugestion, but unfortunately it doesn’t works.
It keeps displayed the first fit, but the second one is not drawed.

[dastudillo]

Is the first one drawn at all, when you don’t draw the second? In any case, it will be helpful if you show the relevant part of your code, or similar code showing the issue.

[Dilicus]

Hi @booghimen,
actually there is no option like same for the fit.
You can check the TGraph::Fit method page.

What you can do, is to avoid to draw the two function during the fitting process using the 0 option of the Fit method, and then draw the two function with the standard draw of the TF1 class.
Have a look a the few lines of code I wrote below.

TF1 *f = new TF1("f","your first function",xmin,xmax);
TF1 *f2 = new TF1("f2","your second function",xmin2,xmax2);

graph->Fit(f,"R0");
graph->Fit(f2,"R0");

graph->Draw();
f->Draw("same");
f2->Draw("same");

Cheers,
S