an>&#160;  <span class="comment">// over { modulus/2, ..., modulus/2 }, except that the two endpoints</span></div>
<div class="line"><a name="l00148"></a><span class="lineno">  148</span>&#160;  <span class="comment">// (which represent the same residue class) occur with half the</span></div>
<div class="line"><a name="l00149"></a><span class="lineno">  149</span>&#160;  <span class="comment">// probability of the others.</span></div>
<div class="line"><a name="l00150"></a><span class="lineno">  150</span>&