//
//

void histfit(void)
{
  gStyle->SetOptStat(1);
  gStyle->SetOptFit(1);

  TH1F *histo = new TH1F("histo","Test Histogram",1024,0,1024);
 
  histo->SetBinContent(84,2);      
  histo->SetBinContent(85,15);     
  histo->SetBinContent(86,37);     
  histo->SetBinContent(87,38);     
  histo->SetBinContent(88,83);     
  histo->SetBinContent(89,146);   
  histo->SetBinContent(90,506);   
  histo->SetBinContent(91,572);   
  histo->SetBinContent(92,632);   
  histo->SetBinContent(93,985);   
  histo->SetBinContent(94,777);   
  histo->SetBinContent(95,250);   
  histo->SetBinContent(96,186);   
  histo->SetBinContent(97,131);   
  histo->SetBinContent(98,124);   
  histo->SetBinContent(99,101);   
  histo->SetBinContent(100,63);   
  histo->SetBinContent(101,52);   
  histo->SetBinContent(102,32);   
  histo->SetBinContent(103,40);   
  histo->SetBinContent(104,27);   
  histo->SetBinContent(105,28);   
  histo->SetBinContent(106,27);   
  histo->SetBinContent(107,13);   
  histo->SetBinContent(108,16);   
  histo->SetBinContent(109,16);   
  histo->SetBinContent(110,8);    
  histo->SetBinContent(111,11);   
  histo->SetBinContent(112,10);   
  histo->SetBinContent(113,9);    
  histo->SetBinContent(114,10);   
  histo->SetBinContent(115,7);    
  histo->SetBinContent(116,10);   
  histo->SetBinContent(117,5);     
  histo->SetBinContent(118,3);     
  histo->SetBinContent(119,4);     
  histo->SetBinContent(120,1);     
  histo->SetBinContent(121,2);     
  histo->SetBinContent(122,1);     
  histo->SetBinContent(123,1);     
  histo->SetBinContent(124,2);     
  histo->SetBinContent(125,2);     
  histo->SetBinContent(126,2);     
  histo->SetBinContent(127,1);     
  histo->SetBinContent(128,1);     
  histo->SetBinContent(129,4);     
  histo->SetBinContent(130,0);     
  histo->SetBinContent(131,0);     
  histo->SetBinContent(132,0);     
  histo->SetBinContent(133,1);     
  histo->SetBinContent(134,0);     
  histo->SetBinContent(135,2);     
  histo->SetBinContent(136,2);     
  histo->SetBinContent(137,0);     

  TF1 *land_1 = new TF1("land_1",land_1_func,0,200,3);
  land_1->SetParameters(2000,2.0,92);
  land_1->SetParLimits(0,500,50000);
  land_1->SetParLimits(1,1.5,2.5);
  land_1->SetParLimits(2,50,150);

  land_1->SetLineWidth(5);
  
  histo->Fit("land_1","b0");

  TCanvas *c1 = new TCanvas("c1","c1",800,600);
  c1->Divide(2,1);
  c1->cd(1);
  histo->DrawCopy("");
  c1->cd(2);
  land_1->Draw("");
 
  return;
}

//
//
Double_t land_1_func(Double_t *x, Double_t *par)
{
  return par[0] * TMath::Exp(par[1]*(par[2]-x[0])-TMath::Exp(par[2]-x[0]));
}