pan class="identifier">i</span><span class="special">);</span>  <span class="comment">// Single tangent number (default policy).</span>

<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Policy</span><span class="special">&gt;</span>
<span class="identifier">T</span> <span class="identifier">tangent_t2n</span><span class="special"