e> which is equal to <code>delta - x - delta</code>, as <code>delta</code> is the lower endpoint in that case. The <code>delta</code> terms cancel out, and we are left with a high-precision version of <code>x</code>. We don’t encounter the same problem at the upper limit <span class="math inline">\(b\)</span> so we don’t adjust the code for that case.</p>
<p>Note, <code>xc</code> is only used for definite integrals. If either the left endpoint is at negative infinity or the right endpoint is at positive