{

  //***************************************

  // macro for Bs2PhiMuMu @ 13TeV

  //***************************************



#include <TApplication.h>
#include <TROOT.h>
#include <TStyle.h>
#include <TCanvas.h>
#include <TGaxis.h>
#include <TFile.h>
#include <TTree.h>
#include <TH1D.h>

Double_t myfitfunction(Double_t *x, Double_t *par){
  Double_t signal = par[0]+ par[1]*x[0] + par[2]*x[0]*x[0];

  return (signal);
  
  }


  void macro_fit(){

    gStyle->SetOptFit(1);
    gStyle->SetOptStat(1);
    gStyle->SetPadBorderMode(0);
    gStyle->SetStatX(0.997);
    gStyle->SetStatY(0.997);
    gStyle->SetPadTickX(1);
    gStyle->SetPadTickY(1);
    gStyle->SetFrameFillColor(10);
    gStyle->SetFrameFillColor(10);
    gStyle->SetTitleFillColor(33);
    gStyle->SetTitleW(.77);
    gStyle->SetTitleH(.07);
    gStyle->SetTitleFillColor(33);
    gStyle->SetHistMinimumZero(false);

    TChain *ch = new TChain("Task1");
    ch->Add("/home/deepak/Desktop/Jazz/18-03-08-full.root");
    //  ch->Add("/home/deepak/Desktop/Jazz/18-03-09-10-34.root");
    //  ch->Add("/home/deepak/Desktop/Jazz/18-03-10-11-17.root");
    //    ch->Add("/home/deepak/Desktop/Jazz/18-03-11-09-23.root");
    TTree *tr = ch;

    TH1D *h_mm   = new TH1D("h_mm"  ,"Muon Lifetime ; #mu life time (#mus) ; Freequency", 50,200, 10000 );

    TCut jpR = "x < 40000";
    TCut selbm = jpR;

    TF1 *fSpectrum = new TF1("fSpectrum", myfitfunction, 200, 10000,3);

    fSpectrum->SetParameters(0, 2, 2);
    Double_t fitParameters[3];
    fSpectrum->GetParameters(fitParameters);

    TCanvas *cv1 = new TCanvas("cv1","",600,600);
    tr->Draw("x >> h_mm", selbm);
    h_mm->Fit("fSpectrum");
    h_mm->GetYaxis()->SetTitleOffset(1.5);
    h_mm->Draw();
    cv1->SaveAs("18-03-11_fit.pdf");

  }