e model will halt with a
diagnostic error message.</p>
<p>The final step in the log probability function calculation is to
execute the statements defined in the model block.</p>
<p>As the log probability function executes, it accumulates an in-memory
representation of the expression tree used to calculate the log
probability. This includes all of the transformed parameter
operations and all of the Jacobian adjustments. This tree is then
used to evaluate the gradients by propagating partial derivatives
backw