th inline">\(3 \times 3\)</span> matrix is known to be zero at indexes <span class="math inline">\([1,2]\)</span> and <span class="math inline">\([1,3]\)</span>. The indexes for parameters are included in a “melted” data-frame or database format.</p>
<pre><code>transformed data {
  array[7, 2] int&lt;lower=1, upper=3&gt; idxs
    = { {1, 1},
        {2, 1}, {2, 2}, {2, 3},
        {3, 1}, {3, 2}, {3, 3} };
  // ...</code></pre>
<p>The seven remaining parameters are declared as a vector.</p>
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