{
gROOT->Reset();

gStyle->SetOptStat(1111111);
gStyle->SetOptFit(1111);

c1 = new TCanvas("c1","gerrors2",0,0,500,500);

Int_t n = 3;

Float_t x[]  = {2.,4.,6.};
Float_t y[]  = {2.,4.,6.};
Float_t ex[] = {0.,0.,0.};
Float_t ey[] = {0.,0.,0.};


gr = new TGraphErrors(n,x,y,ex,ey);

func = new TF1("func","[0]*x+[1]");
gr.Fit("func");


gr->Draw("A*");

}