// Reads the points from a file and produces a simple graph.
int macro2(){
    
    TCanvas* c=new TCanvas();
    c->SetGrid();
    
    TGraphErrors graph_expected("./macro2_input_expected.txt",
                                "%lg %lg %lg");
    graph_expected.SetTitle(
       "Measurement XYZ and Expectation;
        lenght [cm];
        Arb.Units");
    graph_expected.SetFillColor(kYellow);
    graph_expected.DrawClone("E3AL"); // E3 draws the band
    
    TGraphErrors graph("./macro2_input.txt","%lg %lg %lg");
    graph.SetMarkerStyle(kCircle);
    graph.SetFillColor(0);
    graph.DrawClone("PESame"); 
    
    // Draw the Legend
    TLegend leg(.1,.7,.3,.9,"Lab. Lesson 2");
    leg.SetFillColor(0);
    leg.AddEntry(&graph_expected,"Expected Points");
    leg.AddEntry(&graph,"Measured Points");
    leg.DrawClone("Same");
    
    graph.Print();
}
