// Example of graph with setpoints
{
 
 // Define Data
 g = new TGraph();

 double x,y;
 
 for(i=0; i<10; i++) {
 x = 0.5 * i;
 y = 4*x + 2 + gRandom->Gaus(0,1);
 g->SetPoint(i, x, y);
 }
 
 // Define Fit Function
 f = new TF1("f", "[0]*x + [1]", 0, 5);
 g->Fit(f);


 g->SetMarkerStyle(22);
 g->Draw("AP");

}