void sipm_plotBiasScan(void)
{
// 
// Input the .csv data file from excel file into arrays for processing.
//

//#include <TMath.h>
#include <TRandom.h>
#include <TTree.h>

gROOT->Reset();
//TTree *Bfield = (TTree *) gROOT->FindObject("Bfield");
//gROOT->LoadMacro("$ROOTSYS/test/libEvent.so"); 
gStyle->SetPalette(1,0);
gStyle->SetOptStat(kFALSE);
// gStyle->SetOptFit(kFALSE);
gStyle->SetOptFit(1111);
gStyle->SetPadRightMargin(0.15);
gStyle->SetPadLeftMargin(0.15);
gStyle->SetPadBottomMargin(0.15);
gStyle->SetFillColor(0);
//

   char line[1024];
   char filename[132];
   char name[10];
   Double_t pi=3.14159;
   Int_t j,jj;
   

   # define npts1 10;   
   Double_t HVps1[npts1]={0,77.8,78.1,78.3,78.6,78.7,78.9,79.0,79.1,90};
   Double_t bcal_res_ratio1[npts1]={-1,2.74,2.14,1.94,1.82,1.80,1.786,1.86,2.19,-1};
   Double_t HVbias1[npts1];

   # define npts2 13;  
   Double_t HVps2[npts2]={0,77.3,77.5,77.8,78.1,78.3,78.6,78.9,79.1,78.7,79,78.9,90};
   Double_t bcal_res_ratio2[npts2]={-1,5.55,3.75,2.55,2.04,1.87,1.76,1.70,1.87,1.74,1.72.1.71,-1};
   Double_t HVbias2[npts2];
   
   # define npts3 12;   
   Double_t HVbias3[npts3]={0,74.5,74.3,74.2,73.9,73.5,73.2,72.9,73.7,73.6,72.4,90};
   Double_t compact_res_ratio3[npts3]={-1,3.46,2.71,2.26,1.73,1.83,2.01,2.7,1.70,1.75,-1};

   # define npts4 12;  
   Double_t HVbias4[npts4]={0,74.5,74.3,74.2,73.9,73.5,73.2,72.9,73.7,73.6,72.4,90};
   Double_t compact_res_ratio4[npts4]={-1,3.12,2.48,2.11,1.60,1.62,1.73,2.21,1.57,1.58,-1};

   // scale production resolutions by geometric factors (sqrt(0.48) for prod,  sqrt(0.59) for compact)
  Double_t geometry1=sqrt(0.48);
  Double_t geometry2=sqrt(0.48);
  Double_t geometry3=sqrt(0.59);
  Double_t geometry4=sqrt(0.59);

   // obtain bias voltages

   Double_t p0 = -2.272;
   Double_t p1 = 0.9462;
   for (jj=0; jj<npts1;jj++) {
          HVbias1[jj] =  p0 + p1*HVps1[jj];
           bcal_res_ratio1[jj] = bcal_res_ratio1[jj]*geometry1;
          }        

   for (jj=0; jj<npts2;jj++) {
          // HVbias2[jj] =  70.1+(HVps2[jj]-76.5)*((72.4-70.1)/(79-76.5))+1.5;
          HVbias2[jj] =  p0 + p1*HVps2[jj];
           bcal_res_ratio2[jj] = bcal_res_ratio2[jj]*geometry2;
          }       

   for (jj=0; jj<npts2;jj++) {
          HVbias3[jj] =  HVbias3[jj] - 1.5;
          HVbias4[jj] =  HVbias4[jj] - 1.5;
          }  

   for (jj=0; jj<npts3;jj++) {
           compact_res_ratio3[jj] = compact_res_ratio3[jj]*geometry3;
          }      
 
   for (jj=0; jj<npts4;jj++) {
           compact_res_ratio4[jj] = compact_res_ratio4[jj]*geometry4;
          }   


   Double_t xmin=71;
   Double_t xmax=73; 
   Double_t ymin=0;
   Double_t ymax=4;

   //
   TCanvas *c1 = new TCanvas("c1","c1 sipm_plotBiasScan Canvas",200,10,700,500);
   c1->SetBorderMode(0);
   c1->SetFillColor(0);
   c1->SetGridx();
   c1->SetGridy();

   TGraph *bcal_res1 = new TGraph (npts1,HVbias1,bcal_res_ratio1);
   TGraph *bcal_res2 = new TGraph (npts2,HVbias2,bcal_res_ratio2);
   TGraph *compact_res3 = new TGraph (npts3,HVbias3,compact_res_ratio3);
   TGraph *compact_res4 = new TGraph (npts4,HVbias4,compact_res_ratio4);


   TLegend *leg2 = new TLegend(0.5,0.75,0.85,0.9);
   leg2->AddEntry(bcal_res2,"BCAL  production","p");
   leg2->AddEntry(compact_res3,"Compact 1","p");
   leg2->AddEntry(compact_res4,"Compact 2","p");

   /*t1 = new TLatex(0.5,0.8,string);
   t1->SetTextColor(1);
   t1->SetNDC();
   t1->Draw();*/

   bcal_res2->SetTitle("");
   bcal_res2->GetXaxis()->SetRangeUser(xmin,xmax);
   bcal_res2->GetYaxis()->SetRangeUser(ymin,ymax);
   bcal_res2->GetXaxis()->SetTitleSize(0.05);
   bcal_res2->GetYaxis()->SetTitleSize(0.05);
   bcal_res2->GetYaxis()->SetTitleOffset(1.5);
   bcal_res2->GetYaxis()->SetTitle("Resolution Ratio");
   bcal_res2->GetXaxis()->SetTitle("SiPM Bias (V)");
   bcal_res2->GetXaxis()->SetNdivisions(5);
   bcal_res2->SetMarkerColor(2);
   bcal_res2->SetMarkerStyle(24);
   bcal_res2->SetMarkerSize(1.2);
   bcal_res2->Draw("AP");
   leg2->Draw();

  Double_t fitmin=xmin;
  Double_t fitmax=xmax;
  // bcal_res2->Fit("pol1","","",fitmin,fitmax);

   bcal_res2->SetMarkerColor(2);
   bcal_res2->SetMarkerStyle(20);
   bcal_res2->SetMarkerSize(1.2);
   // bcal_res2->Draw("SameP");

   compact_res3->SetMarkerColor(4);
   compact_res3->SetMarkerStyle(25);
   compact_res3->SetMarkerSize(1.2);
   compact_res3->Draw("SameP");

   compact_res4->SetMarkerColor(4);
   compact_res4->SetMarkerStyle(21);
   compact_res4->SetMarkerSize(1.2);
   compact_res4->Draw("SameP");



  c1->SaveAs("sipm_plotBiasScan_c1.pdf");


  // close input file
}