h3 align = "center">
      Usage:
    </h3>

    <p>
      <blockquote>
        [ <i>c</i>, <i>index</i> ] = <b>subset_sum</b> ( <i>w</i>, <i>t</i>, <i>r</i> )
      </blockquote>
      where
      <ul>
        <li>
          <i>w</i>, a set of N weights.  N must be no more than 31.
        </li>
        <li>
          <i>t</i>, the target value.
        </li>
        <li>
          <i>r</i>, a vector of length 2, containing the lower and upper
          limits to be searched.  To search the entire range, u