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TGraphFit.C
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TGraphFit.C
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void TGraphFit(){
//
// Draw a graph with error bars and fit a function to it
//
gStyle->SetOptFit(111) ; //superimpose fit results
// make nice Canvas
TCanvas *c1 = new TCanvas("c1" ,"Daten" ,200 ,10 ,700 ,500) ;
c1->SetGrid( ) ;
//define some data points ...
const Int_t n = 10;
Float_t x[n] = {-0.22, 0.1, 0.25, 0.35, 0.5, 0.61, 0.7, 0.85, 0.89, 1.1};
Float_t y[n] = {0.7, 2.9, 5.6, 7.4, 9., 9.6, 8.7, 6.3, 4.5, 1.1};
Float_t ey[n] = {.8 ,.7 ,.6 ,.5 ,.4 ,.4 ,.5 ,.6 ,.7 ,.8};
Float_t ex[n] = {.05 ,.1 ,.07 ,.07 ,.04 ,.05 ,.06 ,.07 ,.08 ,.05};
// and hand over to TGraphErros object
TGraphErrors *gr = new TGraphErrors(n,x,y,ex,ey);
gr->SetTitle("TGraphErrors with Fit") ;
gr->Draw("AP");
// now perform a fit (with errors in x and y!)
gr->Fit("gaus");
c1->Update();
}