void CSvsE(){
TCanvas *c1 = new TCanvas("c1","A Simple Graph Example",800,500);
c1->SetGrid();
c1->SetTickx();
c1->SetTicky();
TMultiGraph *multigraph = new TMultiGraph();
multigraph->SetTitle("Cross-section vs CM Energy");
multigraph->GetXaxis()->SetTitle("#sqrt{s}(GeV)");
multigraph->GetYaxis()->SetTitle("#sigma(pb)");
TLegend *legend = new TLegend(0.72,0.15,0.88,0.35,NULL,"brNDC");
legend->SetTextSize(0.03);
float max = 35;
// larger area
Double_t x1[5] = { 500, 1200, 1200, 500, 500};
Double_t y1[5] = { 0, 0, max, max, 0};
auto excl1 = new TGraph(5,x1,y1);
excl1->SetLineColor(41);
excl1->SetFillColor(41);
excl1->SetFillStyle(1001);
// smaller area
Double_t x2[5] = { 0, 500, 500, 0, 0};
Double_t y2[5] = { 0, 0, max, max, 0};
auto excl2 = new TGraph(5,x2,y2);
excl2->SetLineColor(46);
excl2->SetFillColor(46);
excl2->SetFillStyle(1001);
TGraph *g1 = new TGraph("CSvsE.txt", "%lg %lg");
g1->SetLineColor(217);
g1->SetLineWidth(3);
g1->SetLineStyle(1);
TGraph *g2 = new TGraph("CSvsE.txt", "%lg %*lg %lg");
g2->SetLineColor(217);
g2->SetLineWidth(3);
g2->SetLineStyle(2);
TGraph *g3 = new TGraph("CSvsE.txt", "%lg %*lg %*lg %lg");
g3->SetLineColor(217);
g3->SetLineWidth(3);
g3->SetLineStyle(3);
multigraph->Add(excl1,"F");
multigraph->Add(excl2,"F");
multigraph->Add(g1,"L");
multigraph->Add(g2,"L");
multigraph->Add(g3,"L");
multigraph->Draw("A*");
gPad->RedrawAxis();
gPad->RedrawAxis("G");
TPaveText *pt = new TPaveText(1500,25.,2100,27.5);
pt->AddText("M=100 GeV");
pt->SetTextColor(1);
pt->SetTextSize(0.04);
pt->SetShadowColor(0);
pt->Draw();
legend->AddEntry(g1,"Sample-1","l");
legend->AddEntry(g2,"Sample-2","l");
legend->AddEntry(g3,"Sample-3","l");
legend->Draw();
multigraph->GetXaxis()->SetLimits(200., 3250.);
multigraph->SetMinimum(0.);
multigraph->SetMaximum(max);
c1->Print("CSvsE.png");
}
