eno">   42</span>  }</div>
<div class="line"><a id="l00043" name="l00043"></a><span class="lineno">   43</span> </div>
<div class="line"><a id="l00044" name="l00044"></a><span class="lineno">   44</span>  <span class="comment">// given a n-th root of unity omega_n, return a r-th root of unity</span></div>
<div class="line"><a id="l00045" name="l00045"></a><span class="lineno">   45</span>  <span class="comment">// for r &lt;= n</span></div>
<div class="line"><a id="l00046" name="l00046"></a><span class="lin