pan><span class="identifier">declval</span><span class="special">&lt;</span><span class="identifier">Real</span><span class="special">&gt;()))</span>
</pre>
<p>
      Integrates <span class="emphasis"><em>f</em></span> over (a,b), and optionally sets <code class="computeroutput"><span class="special">*</span><span class="identifier">pL1</span></code> to the
      L1 norm of the returned value: if this is substantially larger than the return
      value, then the sum was ill-conditioned. Note however, that n