// Landau fit Double_t z_dif_landau(Double_t *x, Double_t *par) { // par[0]=norm, par[2]=most probable value, par[2]=lambda or width // par[0]=605.5, par[1]=2.1532, par[2]=1.8978 return par[0]*TMath::Landau(par[1],par[2]); }