eangle_slope.cxx

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void eangle_slope()
{
    TFile *f=new TFile("../../Eangle1DSec/eangle.root");
    ostringstream strout;
    strout<<"ddgcalib";
    TTree *tree = f->Get(strout.str().c_str()); 
    double dedx[100],eangle[100];
    tree->SetBranchAddress("truncgain",dedx);
    tree->SetBranchAddress("eangle",eangle);
    tree->GetEntry(0);
 
    TFile *f_new=new TFile("eangle.root");
    TTree *tree_new = f_new->Get(strout.str().c_str()); 
    double dedx_new[100],eangle_new[100];
    tree_new->SetBranchAddress("truncgain",dedx_new);
    tree_new->SetBranchAddress("eangle",eangle_new);
    tree_new->GetEntry(0);
 
    double step = 0.5/100;
    double x[100];
    for(int i=0; i<100; i++) x[i] = -0.25 + i*step;
    TGraph *g_old = new TGraph(100, x, dedx);
    g_old->SetMarkerColor(2);
    g_old->SetLineColor(2);
    g_old->SetMarkerSize(1.0);
    g_old->SetMarkerStyle(20);
    TGraph *g_new = new TGraph(100, x, dedx_new);
    g_new->SetMarkerColor(4);
    g_new->SetLineColor(4);
    g_new->SetMarkerSize(1.0);
    g_new->SetMarkerStyle(20);
    TCanvas *c1 = new TCanvas("c1","dE/dx vs entra-angle", 10,10,800,642);
    g_old->Draw("ap");
    g_new->Draw("p,same");
    TLegend *l_old = new TLegend(.65, .35, .89, .50);
    l_old->AddEntry(g_old, "old", "pl");
    TLegend *l_new = new TLegend(.65, .20, .89, .35);
    l_new->AddEntry(g_new, "new", "pl");
    l_old->Draw();
    l_new->Draw();
    c1->SaveAs("figs/eangle_slope.eps");   
}