mbda) = \frac{\lambda}{2} \ \exp
\left(\frac{\lambda}{2} \left(2\mu + \lambda \sigma^2 -
2y\right)\right) \text{erfc}\left(\frac{\mu + \lambda\sigma^2 -
y}{\sqrt{2}\sigma}\right) . \]</span></p>
</div>
<div id="sampling-statement-24" class="section level3">
<h3><span class="header-section-number">15.3.2</span> Sampling Statement</h3>
<p><code>y ~</code> <strong><code>exp_mod_normal</code></strong><code>(mu, sigma, lambda)</code></p>
<p>Increment target log probability density with <code>exp_mod_normal_lpdf(