void testrange() {

  Double_t x[10] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
  Double_t y[10] = { 1.1, 2.1, 3.1, 4.1, 5.1, 6.1, 7.1, 8.1, 9.1, 10.1 };

  TGraph *gr = new TGraph( 10, x, y ) ;
  
  gr->SetMarkerStyle(20 );gr->SetMarkerColor(2);gr->SetMarkerSize(1.0);

  gr->GetXaxis()->SetLimits( 3, 8 );
  gr->GetYaxis()->SetLimits( 3, 8 );

  gr->GetXaxis()->SetRangeUser( 3, 8 );
  gr->GetYaxis()->SetRangeUser( 3, 8 );

  gr->Draw("APL");

}