void exemplo_TGraph_2()
{
 float x[]  = {1,2,3,4,5,6};
 float y[]  = {0.1,0.3,0.5,0.7,0.9,1.1};
 float ex[] = {0.1,0.1,0.1,0.1,0.1,0.1};
 float ey[] = {0.02,0.03,0.02,0.04,0.03,0.05};
 TGraphErrors *g = new TGraphErrors(6,x,y,ex,ey);
 g->Draw("AP"); // A desenha os eixos, P desenha pontos
 g->SetMarkerStyle(20); // estilo do ponto 20 = circulo
 g->SetMarkerColor(2);
 g->SetLineColor(4);
 g->SetTitle("Um exemplo de grafico");
 g->GetXaxis()->SetTitle("eixo-X");
 g->GetYaxis()->SetTitle("eixo-Y");
 return;
}