xt</a>, the indices of nodes that make the elements.
        </li>
        <li>
          <a href = "pool_values.txt">
          pool_values.txt</a>, the value associated with each element.
        </li>
        <li>
          <a href = "pool_mesh.png">
          pool_mesh.png</a>, 
          an "overhead" view of the quadrilateral mesh.
        </li>
        <li>
          <a href = "pool_function.png">
          pool_function.png</a>, 
          a 3D view of the function over the quadrilateral mesh.
     