void plot_2body(void)
{
// Input root file created with kinematics_2body and plot variables.
//    Original: Dec 09, 2009
//
//

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

gROOT->Reset();
TFile *tfile = new TFile("kinematics_2body.root");
TTree *twobody = (TTree *) gROOT->FindObject("twobody");
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];
   char filename[132];
   Int_t j,jj;
   
   #define npts 8;
   #define pi 3.14159265;

   Double_t xmin=2;
   Double_t xmax=4;
   Double_t ymin=0.5;
   Double_t ymax=2.5;

   twobody->Print();
   
   //
   TCanvas *c1 = new TCanvas("c1","Plot_2body Canvas",200,10,700,700);
   c1->SetBorderMode(0);
   c1->SetFillColor(0);

   c1->SetGridx();
   c1->SetGridy();
   c1->SetBorderMode(0);
   c1->SetFillColor(0);
   c1->Divide(2,2);

   c1->cd(1);

   twobody->SetMarkerStyle(20);
   twobody->SetMarkerSize(0.3);
   twobody->SetMarkerColor(2);
   twobody->SetTitle("");
   twobody->Draw("theta_recoil:theta_scat");

   c1->cd(2);
   twobody->Draw("Precoil:theta_recoil");
   c1->cd(3);
   // twobody->Draw("Precoil:theta_scat","theta_scat<0.5");
   twobody->Draw("Precoil:theta_scat");
   c1->cd(4);
   twobody->Draw("Erecoil-mrecoil:Precoil");

   /*TH2F *thr_vs_ths = new TH2F("thr_vs_ths","Theta recoil vs theta scat"
   TGraph *thresh = new TGraph (npts,combins,threshold);
   TLegend *leg = new TLegend(0.15,0.70,0.35,0.9);
   leg->AddEntry(thresh,"Combinations","p");

   sprintf (string,"Hello=%s\n","hello");
   printf ("%s",string);

   contour->SetTitle("");
   contour->GetXaxis()->SetRangeUser(xmin,xmax);
   contour->GetYaxis()->SetRangeUser(ymin,ymax);
   contour->GetXaxis()->SetTitleSize(0.05);
   contour->GetYaxis()->SetTitleSize(0.05);
   contour->GetYaxis()->SetTitleOffset(1.5);
   contour->GetXaxis()->SetTitle("m_{Kp}^{2}");
   contour->GetYaxis()->SetTitle("m_{KK}^{2}");
   contour->GetXaxis()->SetNdivisions(5);
   contour->SetMarkerColor(1);
   contour->SetMarkerStyle(21);
   contour->Draw("AL");

   sprintf(string,"m1=%f\n",m1);
   t1 = new TLatex(0.4,0.85,string);
   t1->SetTextColor(1);
   t1->SetNDC();
   t1->Draw();*/

   c1->SaveAs("plot_2body.eps");
   c1->SaveAs("plot_2body.pdf");

}