void plot_goodfits(void)
{
// 
// plot the number of fits to a cdc segment that result in prob > prob_cut (currently set to 0.01).
//

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

gROOT->Reset();
//TTree *Bfield = (TTree *) gROOT->FindObject("Bfield");
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 string[256];
   Int_t j,jj;
   
   #define npts 6;
   Int_t ngen=10000;

   // input data set first point (actually -3) to -10 so that it is not plotted.

   // use offset on x-axis to make data visible.

   Double_t layers0[npts]={0,2,3,4,5,6};
   Double_t layers1[npts]={0,2.1,3.1,4.1,5.1,6.1};
   Double_t layers1a[npts]={0,1.9,2.9,3.9,4.9,5.9};
   Double_t layers2[npts]={0,2.2,3.2,4.2,5.2,6.2};
   Double_t layers3[npts]={0,2.3,3.3,4.3,5.3,6.3};
   Double_t standard[npts]={0,40000,18344,16453,16156,16387};
   Double_t shifted[npts]={0,40000,13689,12250,12703,13274};
   Double_t shifted_eff[npts]={0,40000,12560,12470,12730,13250};
   Double_t closepack[npts]={0,40000,12927,12023,13052,14797};
   // Double_t closepack_eff[npts]={0,40000,19095,17103,21886,32569};  original eff (enlarging errors)
   Double_t closepack_eff[npts]={0,40000,11079,12365,13351,15048};
   Double_t closepack_eff3[npts]={0,40000,9982,12367,13554,15046};
   Double_t shifted_false[npts]={0,-1,0.228,0.088,0.052,.044};
   Double_t closepack_false[npts]={0,-1,0.144,0.109,0.12,0.158};
   Double_t closepack_false3[npts]={0,-1,0.582,0.174,0.187,0.208};
   Double_t xmin=1;
   Double_t xmax=7;
   Double_t ymin=0;
   Double_t ymax=4;

   // normalize to number of generated events

   for (j=0;j<npts;j++) {
       standard[j] = standard[j]/ngen;
       shifted[j] = shifted[j]/ngen;
       shifted_eff[j] = shifted_eff[j]/ngen;
       closepack[j] = closepack[j]/ngen;
       closepack_eff[j] = closepack_eff[j]/ngen;
       closepack_eff3[j] = closepack_eff3[j]/ngen;
   }


   //
   TCanvas *c1 = new TCanvas("c1","Number of good segements per event",200,10,700,700);
   c1->SetBorderMode(0);
   c1->SetFillColor(0);

   c1->SetGridx();
   c1->SetGridy();
   c1->SetBorderMode(0);
   c1->SetFillColor(0);


   TGraph *stand = new TGraph (npts,layers1a,standard);
   TGraph *shift = new TGraph (npts,layers0,shifted);
   TGraph *shift_eff = new TGraph (npts,layers1,shifted_eff);
   TGraph *shift_false = new TGraph (npts,layers1,shifted_false);
   TGraph *packed = new TGraph (npts,layers2,closepack);
   TGraph *packed_eff = new TGraph (npts,layers2,closepack_eff);
   TGraph *packed_eff3 = new TGraph (npts,layers3,closepack_eff3);
   TGraph *packed_false = new TGraph (npts,layers2,closepack_false);
   TGraph *packed_false3 = new TGraph (npts,layers3,closepack_false3);
   TLegend *leg = new TLegend(0.35,0.60,0.85,0.9);
   leg->AddEntry(stand,"Standard","p");
   leg->AddEntry(shift,"Shifted","p");
   leg->AddEntry(shift_eff,"Shifted/thresh","p");
   leg->AddEntry(shift_false,"FALSE Shifted/thresh","p");
   leg->AddEntry(packed,"Close-pack/none","p");
   leg->AddEntry(packed_eff,"Close-pack/geom","p");
   leg->AddEntry(packed_eff3,"Close-pack/geom+thresh","p");
   leg->AddEntry(packed_false,"FALSE Close-pack/geom","p");
   leg->AddEntry(packed_false3,"FALSE Close-pack/geom+thresh","p");

   stand->SetTitle("");
   stand->GetXaxis()->SetRangeUser(xmin,xmax);
   stand->GetYaxis()->SetRangeUser(ymin,ymax);
   stand->GetXaxis()->SetTitleSize(0.04);
   stand->GetYaxis()->SetTitleSize(0.04);
   stand->GetYaxis()->SetTitleOffset(1.5);
   stand->GetXaxis()->SetTitle("Number of Layers");
   stand->GetYaxis()->SetTitle("Number of segments per event (p>0.01)");
   stand->SetMarkerColor(1);
   stand->SetMarkerStyle(21);
   stand->Draw("AP");
   shift->SetMarkerColor(4);
   shift->SetMarkerStyle(21);
   shift->Draw("sameP");
   shift_eff->SetMarkerColor(2);
   shift_eff->SetMarkerStyle(21);
   shift_eff->Draw("sameP");
   shift_false->SetMarkerColor(2);
   shift_false->SetMarkerStyle(25);
   shift_false->Draw("sameP");
   packed->SetMarkerColor(4);
   packed->SetMarkerStyle(22);
   packed->Draw("sameP");
   packed_eff->SetMarkerColor(2);
   packed_eff->SetMarkerStyle(22);
   packed_eff->Draw("sameP");
   packed_eff3->SetMarkerColor(2);
   packed_eff3->SetMarkerStyle(20);
   packed_eff3->Draw("sameP");
   packed_false->SetMarkerColor(2);
   packed_false->SetMarkerStyle(26);
   packed_false->Draw("sameP");
   packed_false3->SetMarkerColor(2);
   packed_false3->SetMarkerStyle(24);
   packed_false3->Draw("sameP");
   leg->Draw();

   // fit data to function

   /*TF1 *expon1 = new TF1("expon","expo",1,10);

   stand->Fit(expon1,"R");
   Double_t A1=expon1->GetParameter(0);
   Double_t B1=expon1->GetParameter(1);
   expon1->SetLineColor(1);
   sprintf(string,"stand: Parameters A=%f,B=%f\n",exp(A1),B1);
   printf("string=%s\n",string);*/


   /*sprintf(string,"Standard\n");
   t1 = new TLatex(0.2,0.8,string);
   t1->SetTextColor(1);
   t1->SetNDC();
   t1->SetTextSize(0.035);
   t1->Draw();*/

   //

   c1->SaveAs("plot_goodfits.eps");
   c1->SaveAs("plot_goodfits.gif");

}