Draw("surf1");
        graph2d->SetLineWidth(2);
        graph2d->Draw(" triw p0 same");
     }
     </pre>
</li>
<li> The X and Y vectors are normalized in order to compute the triangles.
     The scale factor used was the same for the X and Y axis.
     This generated problems (very long triangles instead of the obvious ones)
     in some cases when the X and Y axis had very different ranges. Having two
     scale factors, one for the X axis and one for the Y axis, cures the problem.</li>
</ul>

<h4>TGrap