How to Work in Root Working with Histograms

• Fitting a histogram:

  • (predefined: gaus, expo, poln, etc.)hist->Fit("gaus");
    • See TH1::Fit
  • User defined function:TF1 *g1 = new TF1("g1","gaus+exp",-0.5,0.5);hist->Fit("g1","R");
  • Obtaining fit parameters:Float_t par0 = gaus->GetParameter(0);Float_t Err_par0 = gaus->GetParError(0);printf("G1 param3 = %f\n",g1->GetParameter(3));
  • Setting initial fit parameters:g1->SetParameter(3,0.453); org1->SetParameters(0.43,2.56,0.453,6.7,-1.4);

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