y not be assigned to a column vector.</p>
<pre class="stan"><code>matrix[4, 1] a;
vector[4] b;
// ...
a = b;  // illegal assignment of column vector to matrix
b = a;  // illegal assignment of matrix to column vector</code></pre>
</div>
</div>
<div id="size-declaration-restrictions-1" class="section level3 unnumbered">
<h3>Size declaration restrictions</h3>
<p>An integer expression is used to pick out the sizes of arrays. The
same restrictions as for vector and matrix sizes apply, namely that
the size is dec