void loopMPV( const char* fileName, const char* gr_title ) {

  std::cout << "fileName = " << fileName << "\n";   
  std::ifstream file;
  file.open(fileName);

  if ( !file.good() ) exit(12);

  TString stringName(fileName);
  TString globalName =  ((TObjString*)stringName.Tokenize(".")->At(0))->GetString();

  TString saveFileName;
  saveFileName.Form("%sSave.root",globalName.Data());

  TString picName;
  picName.Form("%s.png",globalName.Data());

  TString cName;
  cName.Form("%s.C",globalName.Data());

  TMultiGraph * mg = new TMultiGraph("mg",gr_title);
  TFile *fSave = new TFile(saveFileName.Data(),"RECREATE");
  fSave->cd();

  std::string rootFileName;

  TGraphErrors *gr;

  int markerstyle, markercolor;

  while( 1 ) {
    file >> rootFileName >> markerstyle >> markercolor;
    if ( file.eof() ) break;
    std::cout << "\t" << rootFileName << "\n";
    gr = readMPV( rootFileName.c_str() );
    gr->SetMarkerStyle(markerstyle);
    gr->SetMarkerColor(markercolor);
    fSave->cd();
    gr->Write();
    mg->Add( gr );
  }	  


  TCanvas* c1= new TCanvas("c1","",800,600);
  c1->cd();
  c1->SetGrid(1,1);

  mg->Draw("AP");
  mg->GetXaxis()->SetTitle("Bias [V]");
  mg->GetYaxis()->SetTitle("MPV [ke]");
  mg->GetXaxis()->SetRangeUser(0.,1000.);
  mg->GetYaxis()->SetRangeUser(0.,30.);


  TLegend* leg = c1->BuildLegend(.55,.66,.90,.85);
  leg->SetName("legend");
  leg->SetFillColor(0);
  leg->SetBorderSize(0);
  leg->SetTextSize(.03);
  leg->Draw();

//  gPad->Modified();
  c1->Update();
  c1->SaveAs(cName.Data());
  c1->SaveAs(picName.Data());
  mg->Write();

  leg->Write();

  fSave->Close();


}	

TGraphErrors* readMPV( const char* rootFileName ) {
  
//  gROOT->Reset();
  gROOT->SetStyle("Plain");

  TString stringName(rootFileName);
  TString globalName =  ((TObjString*)stringName.Tokenize(".")->At(0))->GetString();

  int maxFiles = 100;
      
  TFile *f = new TFile(rootFileName,"READ");
  f->cd();

  float v;
  float mpv;
  float mpverror;

  int fl;
  int cs;
  const char* detName, *period;
  int angle;

  TString *tst_period;
  TString *tst_name;
  TString *tst_fluence;
  TString *tst_angle;


  TIter next(f->GetListOfKeys());
  TKey *key; while ((key=(TKey*)next())) {
    const char* name = key->GetName();
    const char* className = key->GetClassName();
    if ( strcmp( className, "TString" ) == 0 ) {
      if ( strcmp( name, "period" ) == 0 ) {
        tst_period = (TString*)f->Get("period");
      }
      if ( strcmp( name, "name" ) == 0 ) {
        tst_name = (TString*)f->Get("name");
      }
      if ( strcmp( name, "fluence" ) == 0 ) {
        tst_fluence = (TString*)f->Get("fluence");
      }
      if ( strcmp( name, "angle" ) == 0 ) {
        tst_angle = (TString*)f->Get("angle");
      }
    }
  }
  fl = tst_fluence->Atoi();
  detName = tst_name->Data();
  angle = tst_angle->Atoi();
  period = tst_period->Data();

  std::cout << "name\tperiod\tfluence\tangle\n";
  std::cout << detName<<"\t"<<period<<"\t"<<fl<<"\t"<<angle<<"\n";

  TString treeFileName;
  treeFileName.Form("t_%s",globalName.Data());

  std::cout << "treeFileName = " << treeFileName.Data() << "\n";
  
  TTree* t = (TTree*)f->Get(treeFileName.Data());
  TString title;
  title.Form("%s_%s, #phi = %d^{#circ}",detName,period,angle);

  t->SetBranchAddress("mpv",&mpv);
  t->SetBranchAddress("mpverror",&mpverror);
  t->SetBranchAddress("v",&v);
  
  Int_t nentries = (Int_t)t->GetEntries();

  float* Volt = new float[maxFiles];
  float* MPV = new float[maxFiles];
  float* MPVerr = new float[maxFiles];

  int n = 0;


  for (Int_t i=0;i<nentries;i++) {
    t->GetEntry(i);
	Volt[n] = v; 
	MPV[n] = mpv; 
	MPVerr[n] = sqrt((mpv*0.05)*(mpv*0.05)+(0.4)*(0.4));
        n++;
  }
  f->Close();  
  
  TGraphErrors * gr = new TGraphErrors( n, Volt, MPV, 0, MPVerr );
  gr->SetName(treeFileName.Data());
  gr->SetTitle(title.Data());
  gr->SetMarkerStyle(21);
  gr->SetMarkerColor(kRed);
  gr->SetDrawOption("AP");
  gr->SetFillStyle(0);
  
  f->Close();
  gROOT->cd();
  return gr;

}