ferencia como <code>v[i]</code>.
</p><pre class="example">(%i1) load (descriptive)$
(%i2) s2 : read_matrix (file_search (&quot;wind.data&quot;))$
(%i3) subsample (s2, lambda([v], v[1] &gt; 18));
              [ 19.38  15.37  15.12  23.09  25.25 ]
              [                                   ]
              [ 18.29  18.66  19.08  26.08  27.63 ]
(%o3)         [                                   ]
              [ 20.25  21.46  19.95  27.71  23.38 ]
              [                                   ]
     