ss="comment">// Define a termination condition, stop when nearly all digits are correct, but allow for</span>
   <span class="comment">// the fact that we are returning a range, and must have some inaccuracy in the elliptic integral:</span>
   <span class="identifier">eps_tolerance</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="identifier">tol</span><span class="special">(</span><span class="identifier">std</span><span class="special">: