egral</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">value_type</span> <span class="identifier">a</span><span class="special">,</span>
                           <span class="keyword">const</span> <span class="identifier">value_type</span> <span class="identifier">b</span><span class="special">,</span>
                           <span class="keyword">const</span> <span class="identifier">value_type</span> <span class="identifier">tol</span><span class="specia