void trig_efficiency(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 5;
   #define nptsm 2;
   #define npts5 1;

   // input data set first point (actually -1) to -10 so that it is not plotted.

   // use offset on x-axis to make data visible and give negative y-values for reference (not plotted)

   Double_t current[npts]={0,10,30,36,40};
   Double_t xerr[npts]={0.1,0.1,0.1,0.1,0.1};

   // first rates are for 4tracks and 3 sectors

   Double_t Lrate[npts]={-1,0.115,0.090,0.075,-1};
   Double_t Lrate_err[npts]={1,0.005,0.005,0.005,1};
   Double_t Merr[nptsm]={0.1,0.1};
   Double_t Mrate_err[nptsm]={0.005,0.005};
   Double_t Mcurrent[nptsm]={5,30};
   Double_t Mrate[nptsm]={0.125,0.115};
   Double_t B5err[npts5]={0.1};
   Double_t B5rate_err[npts5]={0.01};
   Double_t B5current[npts5]={0};
   Double_t B5rate[npts5]={0.125};

   // rates are for 4tracks and 4 sectors

   Double_t L4rate[npts]={-1,0.055,0.050,0.045,-1};
   Double_t L4rate_err[npts]={1,0.005,0.005,0.005,1};
   Double_t M4rate_err[nptsm]={0.005,0.005};
   Double_t M4rate[nptsm]={0.065,0.060};
   Double_t B54rate_err[nptsm]={0.01,0.01};
   Double_t B54rate[nptsm]={0.065,0.060};

   // rates are for 3tracks and 3 sectors

   Double_t L3rate[npts]={-1,0.17,0.13,0.12,-1};
   Double_t L3rate_err[npts]={1,0.005,0.005,0.005,1};
   Double_t M3rate_err[nptsm]={0.005,0.005};
   Double_t M3rate[nptsm]={0.20,0.18};
   Double_t B53rate_err[nptsm]={0.01,0.01};
   Double_t B53rate[nptsm]={0.20,0.18};

   Double_t xmin=0;
   Double_t xmax=40;
   Double_t ymin=0;
   Double_t ymax=0.4;

   //
   TCanvas *c1 = new TCanvas("c1","Rate of Lambda Production vs Beam Current",200,10,700,700);
   c1->SetBorderMode(0);
   c1->SetFillColor(0);

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


   TGraphErrors *l4t_3s = new TGraphErrors (npts,current,Lrate,xerr,Lrate_err);
   TGraphErrors *m4t_3s = new TGraphErrors (nptsm,Mcurrent,Mrate,Merr,Mrate_err);
   TGraphErrors *B54t_3s = new TGraphErrors (npts5,B5current,B5rate,B5err,B5rate_err);

   TLegend *leg = new TLegend(0.15,0.60,0.7,0.9);
   leg->AddEntry(l4t_3s,"4 Tracks, 3 Sectors Asynch=ST*MOR","p");
   leg->AddEntry(m4t_3s,"4 Tracks, 3 Sectors Asynch=MOR","p");
   leg->AddEntry(B54t_3s,"4 Tracks, 3 Sectors Asynch=ST*MOR Bit 5","p");

   TGraphErrors *l4t_4s = new TGraphErrors (npts,current,L4rate,xerr,L4rate_err);
   TGraphErrors *m4t_4s = new TGraphErrors (nptsm,Mcurrent,M4rate,Merr,M4rate_err);
   TGraphErrors *B54t_4s = new TGraphErrors (npts5,B5current,B54rate,B5err,B54rate_err);
   leg->AddEntry(l4t_4s,"4 Tracks, 4 Sectors Asynch=ST*MOR","p");
   leg->AddEntry(m4t_4s,"4 Tracks, 4 Sectors Asynch=MOR","p");
   leg->AddEntry(B54t_4s,"4 Tracks, 4 Sectors Asynch=ST*MOR Bit 5","p");

   TGraphErrors *l3t_3s = new TGraphErrors (npts,current,L3rate,xerr,L3rate_err);
   TGraphErrors *m3t_3s = new TGraphErrors (nptsm,Mcurrent,M3rate,Merr,M3rate_err);
   TGraphErrors *B53t_3s = new TGraphErrors (npts5,B5current,B53rate,B5err,B53rate_err);
   leg->AddEntry(l3t_3s,"3 Tracks, 3 Sectors Asynch=ST*MOR","p");
   leg->AddEntry(m3t_3s,"3 Tracks, 3 Sectors Asynch=MOR","p");
   leg->AddEntry(B53t_3s,"3 Tracks, 3 Sectors Asynch=ST*MOR Bit 5","p");

   l4t_3s->SetTitle("");
   l4t_3s->GetXaxis()->SetRangeUser(xmin,xmax);
   l4t_3s->GetYaxis()->SetRangeUser(ymin,ymax);
   l4t_3s->GetXaxis()->SetTitleSize(0.04);
   l4t_3s->GetYaxis()->SetTitleSize(0.04);
   l4t_3s->GetYaxis()->SetTitleOffset(1.5);
   l4t_3s->GetXaxis()->SetTitle("Electron Beam Current (nA)");
   l4t_3s->GetYaxis()->SetTitle("Normalized #Lambda rate");
   l4t_3s->GetXaxis()->SetNdivisions(5);

   l4t_3s->SetMarkerColor(1);
   l4t_3s->SetMarkerStyle(20);
   l4t_3s->Draw("AP");
   m4t_3s->SetMarkerColor(1);
   m4t_3s->SetMarkerStyle(24);
   m4t_3s->Draw("P");
   B54t_3s->SetMarkerColor(1);
   B54t_3s->SetMarkerStyle(21);
   B54t_3s->Draw("P");
   

   l4t_4s->SetMarkerColor(2);
   l4t_4s->SetMarkerStyle(20);
   l4t_4s->Draw("P");
   m4t_4s->SetMarkerColor(2);
   m4t_4s->SetMarkerStyle(24);
   m4t_4s->Draw("P");
   B54t_4s->SetMarkerColor(2);
   B54t_4s->SetMarkerStyle(21);
   B54t_4s->Draw("P");

   l3t_3s->SetMarkerColor(4);
   l3t_3s->SetMarkerStyle(20);
   l3t_3s->Draw("P");
   m3t_3s->SetMarkerColor(4);
   m3t_3s->SetMarkerStyle(24);
   m3t_3s->Draw("P");
   B53t_3s->SetMarkerColor(4);
   B53t_3s->SetMarkerStyle(21);
   B53t_3s->Draw("P");


   leg->Draw();

   l4t_3s->Fit("pol1","","",0,40);
   TF1 *p1 = l4t_3s->GetFunction("pol1");
   p1->SetLineColor(1);
   p1->Draw("same");

   m4t_3s->Fit("pol1","","",0,40);
   TF1 *p2 = m4t_3s->GetFunction("pol1");
   p2->SetLineColor(1);
   p2->Draw("same");

   l4t_4s->Fit("pol1","","",0,40);
   TF1 *p3 = l4t_4s->GetFunction("pol1");
   p3->SetLineColor(2);
   p3->Draw("same");

   m4t_4s->Fit("pol1","","",0,40);
   TF1 *p4 = m4t_4s->GetFunction("pol1");
   p4->SetLineColor(2);
   p4->Draw("same");

   l3t_3s->Fit("pol1","","",0,40);
   TF1 *p5 = l3t_3s->GetFunction("pol1");
   p5->SetLineColor(4);
   p5->Draw("same");

   m3t_3s->Fit("pol1","","",0,40);
   TF1 *p6 = m3t_3s->GetFunction("pol1");
   p6->SetLineColor(4);
   p6->Draw("same");

   sprintf(string,"#Lambda rate vs beam current\n");
   t1 = new TLatex(0.45,0.8,string);
   t1->SetTextColor(1);
   t1->SetNDC();
   t1->SetTextSize(0.035);
   // t1->Draw();

   //

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

}
Double_t tradeoff (Double_t *x, Double_t *par) {

   Double_t b=par[0];
   Double_t c=par[1];
   Double_t DeE=par[2];
   Double_t E=par[3];
   Double_t x1=x[0]/100;

   char string[256];


   Double_t P = b*b/(DeE*DeE*E);
   Double_t pde = P/2 + sqrt(P*P/4 + x1*c*c/(DeE*DeE*E*E));
   
   /*sprintf (string,"tradeoff=%f b=%f c=%f DeE=%f E=%f\n",pde,b,c,DeE,E);
   printf ("string=%s",string);*/

   return pde;
}