errors raised by calls to functions inside user functions or return type mismatches are simply passed on; this typically results in a warning message and rejection of a proposal during sampling or optimization.</p>
</section>
<section id="data-only-qualifiers" class="level3 unnumbered">
<h3 class="unnumbered anchored" data-anchor-id="data-only-qualifiers">Data-only qualifiers</h3>
<p>Some of Stan’s built-in functions, like the differential equation solvers, have arguments that must be data. Such data-only