ro.</span>
   <span class="identifier">T</span> <span class="identifier">max</span> <span class="special">=</span> <span class="identifier">arc</span><span class="special">;</span> <span class="comment">// Maximum possible value is the arc length.</span>

   <span class="comment">// Accuracy doubles at each step, so stop when just over half of the digits are</span>
   <span class="comment">// correct, and rely on that step to polish off the remainder:</span>
   <span class="keyword">int</span> <span class="