title: How to get the difference value of two column from .dat-file?
body: <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th style="text-align: left;">Dy</th>
  <th style="text-align: left;">MxT</th>
  <th style="text-align: right;">MnT</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td style="text-align: left;">1</td>
  <td style="text-align: left;">88</td>
  <td style="text-align: right;">59</td>
  </tr>
  <tr>
  <td style="text-align: left;">2</td>
  <td style="text-align: left;">79</td>
  <td style="text-align: right;">63</td>
  </tr>
  <tr>
  <td style="text-align: left;">3</td>
  <td style="text-align: left;">77</td>
  <td style="text-align: right;">55</td>
  </tr>
  </tbody>
  </table>
  </div>
  <p>I have <code>weather.dat</code> file having weather data. First column is day number and 2nd column is max temp &amp; 3rd column is min temp. I need to compare row by row that in which day the the difference in max temp &amp; min temp is minimum. How to do that?</p>