 = b[3];      //   same result as above
x = a[1, 3, 5];  // result is scalar
x = b[3, 5];    //   same result as above
x = c[5];      //   same result as above</code></pre>
<p>Row vectors and other derived vector types (simplex and ordered)
behave the same way in terms of indexing.</p>
<p>Consider the following matrix, vector and scalar declarations.</p>
<pre class="stan"><code>matrix[6, 5] d[3, 4];
matrix[6, 5] e[4];
matrix[6, 5] f;
row_vector[5] g;
real x;</code></pre>
<p>With these declarations, the foll