2 macro Fit

ROOT
8

If you try:

{
  TF1 *f = new TF1("f", "[0] * TMath::Exp(-x * [2] / [1])", 1, 1e4);
  f->SetParameters(11111, 11, 1);
  f->SetMinimum(0.5); f->SetMaximum(5e5);
  f->Draw();
  gPad->SetLogx(); gPad->SetLogy();
  gPad->SetGrid(1, 1);
}

you will clearly see that the “shape” of this function is quite different from the “shapes” of your histograms (used by the “netheta.c” macro).

You really need to talk to people who created these CORSIKA simulations (e.g. about “errors” of all your histograms) and to your “supervisor” (I’m not an expert in showers).