#include <TChain.h>
#include <TH1.h>
#include <TF1.h>
#include <TMath.h>
#include <TFile.h>
#include <TNtuple.h>
#include <TCanvas.h>
#include <iostream.h>
#include <fstream.h>
#include <TChain.h>
#include <TStyle.h>
#include <TPave.h>
#include <TText.h>
#include <TPaveLabel.h>

// fit functions

Double_t bin, xmean, xlow, xhigh;

Double_t DYS_fit (Double_t *x, Double_t *p) {
  Double_t p0 = p[0]*bin / (-1./p[3] + p[1]/p[4] + p[2]/p[5]);
  Double_t x0 = x[0]-xlow;
  Double_t fv = p0 * (-exp(-p[3]*x0) + p[1]*exp(-p[4]*x0) + p[2]*exp(-p[5]*x0));
  return   fv;
}

Double_t DYS_fip (Double_t *x, Double_t *p){
  Double_t xc = xmean-xlow;
  Double_t xv = x[0]-xmean;
  Double_t p0 =
    p[0]*bin / (p[1]*exp(p[3]*xc) + exp(p[4]*xc) + p[2]*exp(p[5]*xc));
  Double_t fv =
    p0 * (p[1]*p[3]*exp(-p[3]*xv) + p[4]*exp(-p[4]*xv) + p[2]*p[5]*exp(-p[5]*xv));
  return   fv;
}

// main function

void testfit(){

  // Get the hist into the root ntuple
  TFile   *file = new TFile("histo.root");
  TH1F    *h1 = (TH1F*) file->Get("h37");

  gStyle->SetOptStat(1111111);
  gStyle->SetOptFit(011111);
  
  // Variables
  Int_t i=0;

  // Declaration of histos
  TH1F *h2 = (TH1F*) h1->Clone();
  h2->SetName("h2");
  TH1F *h3 = (TH1F*) h1->Clone();
  h3->SetName("h3");

  // Fit function
  Float_t parVal[6], parErr[6];
  TF1 *mfit3 = new TF1("mfit3",
		       "[0]*([1]*exp(-[3]*(x-2.2))+exp(-[4]*(x-2.2))+[2]*exp(-[5]*(x-2.2)))",0.,100000.);

  mfit3->SetParName(0,"const0");
  mfit3->SetParName(1,"const1");      
  mfit3->SetParName(2,"const3");      
  mfit3->SetParName(3,"slope1");
  mfit3->SetParName(4,"slope2");
  mfit3->SetParName(5,"slope3");
 
  // Fits
  mfit3->SetParameter(0, 2100);
  mfit3->SetParameter(1, -0.89);   
  mfit3->SetParameter(2, 0.023);
  mfit3->SetParameter(3, 2.20);
  mfit3->SetParameter(4, 2.10);
  mfit3->SetParameter(5, 0.52);

  h2->Fit(mfit3,"","",1.2,15.0);
  for (i=0; i<6; i++) {
    parVal[i] = (Float_t)mfit3->GetParameter(i);
    parErr[i] = (Float_t)mfit3->GetParError (i);
  } 

  //
  bin = 0.1;       xmean = 2.2;   xlow = 1.2;   xhigh = 15.0;

  TF1 *newfit = new TF1("newfit", DYS_fit, xlow,xhigh, 6);
  newfit->SetParameter(0,5729.69);
  newfit->SetParameter(1,0.998238);   
  newfit->SetParameter(2, 0.00475432);
  newfit->SetParameter(3, 2.19718);
  newfit->SetParameter(4, 2.08281);
  newfit->SetParameter(5, 0.518135);
  h3->Fit(newfit,"","",xlow,xhigh);

  TCanvas *c1 = new TCanvas("canvas","canvas", 60, 80,700,700);
  c1->Divide(1,3);
  c1->cd(1);
  gPad->SetLogy();
  h1->Draw();
  c1->cd(2);
  gPad->SetLogy();
  h2->Draw();
  c1->cd(3);
  gPad->SetLogy();
  h3->Draw();
  //h->Fit(newfip,"","",xlow,xhigh);

}