 class="page-wrapper" tabindex="-1" role="main">
          <div class="page-inner">

            <section class="normal" id="section-">

<div>
This is an old version, <a href="https://mc-stan.org/docs/stan-users-guide/user-functions.html#user-defined-probability-functions">view current version</a>.
</div>
<div id="user-defined-probability-functions" class="section level2">
<h2><span class="header-section-number">18.5</span> User-Defined Probability Functions</h2>
<p>Probability functions are distinguished i