o error estimate
      is available. This function supports both finite and infinite <span class="emphasis"><em>a</em></span>
      and <span class="emphasis"><em>b</em></span>, as long as <code class="computeroutput"><span class="identifier">a</span>
      <span class="special">&lt;</span> <span class="identifier">b</span></code>.
    </p>
<p>
      The Gaussian quadrature routine support both real and complex-valued quadrature.
      For example, the Lambert-W function admits the integral representation
 