Facing Problem while fitting

ROOT
18

The first parameter of “gaus” is the “peak’s height” while the first parameter of “gausn” is the “peak’s area”.
In both cases, the second parameter is the “peak’s mean” (i.e. the “peak’s position”).

{
  TGraph *g = new TGraph("eu_gu_1.dat");
  // g->Sort(); // just a precaution
  TF1 *f1 = new TF1("f1", "gausn(0) + pol1(3)", 400., 435.); // linear background
  f1->SetParameters(14000., 415., 2., 0., 0.);
  g->Fit("f1", "BR+");
  TF1 *f2 = new TF1("f2", "gausn(0) + pol1(3)", 1160., 1200.);
  f2->SetParameters(15000., 1178., 2., 0., 0.);
  g->Fit("f2", "BR+");
  TF1 *f3 = new TF1("f3", "gausn", 4795., 4835.); // clean peak, no background
  f3->SetParameters(4400., 4815., 3.);
  g->Fit("f3", "BR+");
  g->Draw("AL");
}

{
  TGraph *g = new TGraph("eu_gu_1.dat");
  // g->Sort(); // just a precaution
  Int_t n = g->GetN();
  Double_t *x = new Double_t[(n + 1)];
  x[0] = (3.0 * g->GetX()[0] - g->GetX()[1]) / 2.0;
  x[n] = (3.0 * g->GetX()[(n - 1)] - g->GetX()[(n - 2)]) / 2.0;
  for (Int_t i = 1; i < n; i++)
    { x[i] = (g->GetX()[(i - 1)] + g->GetX()[i]) / 2.0; }
  TH1D *h = new TH1D("h", "spectrum;x-value;#counts", n, x);
  h->FillN(n, g->GetX(), g->GetY());
  h->Sumw2(kFALSE); // restore proper errors
  delete [] x; // no longer needed
  delete g; // no longer needed
  TF1 *f1 = new TF1("f1", "gausn(0) + pol1(3)", 400., 435.); // linear background
  f1->SetParameters(14000., 415., 2., 0., 0.);
  h->Fit("f1", "BR+"); // e.g. "BR+" or "LBR+"
  TF1 *f2 = new TF1("f2", "gausn(0) + pol1(3)", 1160., 1200.);
  f2->SetParameters(15000., 1178., 2., 0., 0.);
  h->Fit("f2", "BR+"); // e.g. "BR+" or "LBR+"
  TF1 *f3 = new TF1("f3", "gausn", 4795., 4835.); // clean peak, no background
  f3->SetParameters(4400., 4815., 3.);
  h->Fit("f3", "BR+"); // e.g. "BR+" or "LBR+"
}