ode>matrix</code> <strong><code>append_row</code></strong><code>(row_vector x, matrix y)</code><br>
Combine row vector x and matrix y by rows. The row vector and the
matrix must have the same number of columns.</p>
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<p></p>
<p><code>matrix</code> <strong><code>append_row</code></strong><code>(row_vector x, row_vector y)</code><br>
Combine row vectors x and y by row. The row vectors must have the same
number of columns.</p>
<!-- vector; append_row; (v