void TimePlot() {
  /* Generating timedependent quantity Temper and plotting it 
     run as: root -l TimePlot.C                               */

  TCanvas *ct2 = new TCanvas("ct2","ct2",10,10,700,500);
  ct2->SetGrid();
  
  int Year = 2020;
  int Month[12] = {1,2,3,4,5,6,7,8,9,10,11,12};
  int Day[31] = {1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31};
  int Hour[24] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23};
  int Minute = 0;
  int Second = 0;

  int Date;
  float Temper(36.);
  float DT = 0.5;
  int NDate = 0;    
  float date[1000];
  float temper[1000];
  for (int im = 0; im < 1; im++) {
    int jm = im + 6;
    for (int id = 0; id < 10; id++) {
      int jd = id + 20;
      for (int ih = 0; ih < 6; ih++) {
	int jh = ih*3 + 1;
	TDatime t0(Year, Month[jm], Day[jd], Hour[jh], Minute, Second);
	Date = t0.Convert();
	TDatime t1(Date);
	date[NDate] = Date;
	temper[NDate] = Temper + DT*(NDate%3-1);; 
	printf(" Item: %2d Temperature %4.1f at Year: %2d Month: %2d Day: %2d Hour: %2d Minute: %2d Second: %2d \n",
	       NDate, temper[NDate], t1.GetYear(), t1.GetMonth(), t1.GetDay(), t1.GetHour(), t1.GetMinute(), t1.GetSecond() );
	NDate++;
      }
    }
  }

  // Plot 
  printf(" \n Now plot  %2d items \n",NDate);
  TF1 *f2 = new TF1("f2","[0]",0., date[NDate-1]);
  f2->SetParameter(0,37.);
  TGraph *gt = new TGraph(NDate,date,temper);
  gt->SetTitle("Temperature vs Date/Time");
  gt->SetMaximum(40.);
  gt->SetMinimum(35.);
  gt->SetMarkerColor(3);
  gt->SetMarkerSize(0.5);
  gt->SetMarkerStyle(20);
  gt->SetLineColor(5);
  gt->SetLineWidth(2);
  gt->Draw("ALP");
  f2->Draw("SAME");
  gt->GetXaxis()->SetLabelSize(0.04);
// Sets time on the X axis
  gt->GetXaxis()->SetTimeDisplay(1);

  ct2->SaveAs("TemperatureVsDate.pdf");
}