"g1" style="width:600px; height:200px;"></div>

    <p>Mixed (x-axis in middle):</p>
    <div id="g2" style="width:600px; height:200px;"></div>

    <p>All positives (x-axis on bottom):</p>
    <div id="g3" style="width:600px; height:200px;"></div>

    <script type="text/javascript">
      var negs = [];
      var mixed = [];
      var pos = [];
      for (var i = 0; i < 100; i++) {
        negs.push([i, -210 + i, -110 - i]);
        mixed.push([i, -50 + i, 50 - i]);
        pos.push([i, 1000 + 2 * i, 1100