der"></a></h3>
<p>The absolute derivative of the inverse of the upper bound transform is</p>
<p><span class="math display">\[
\left| \,
\frac{d}{dy} \left( b - \exp(y) \right)
\, \right|
= \exp(y).
\]</span></p>
<p>Therefore, the density of the unconstrained variable <span class="math inline">\(Y\)</span> is defined in
terms of the density of the variable <span class="math inline">\(X\)</span> with an upper bound of <span class="math inline">\(b\)</span> by</p>
<p><span class="math display">\[
p_Y(y)
=   p_