_matrix (file_search (&quot;biomed.data&quot;))$
(%i4) subsample (s3, '(%c[1] = B and %c[2] &gt; 38), 3, 4, 5, 6);
                   [ 28.0  102.3  17.1  146 ]
                   [                        ]
                   [ 21.0  92.4   10.3  197 ]
                   [                        ]
                   [ 23.0  111.5  10.0  133 ]
                   [                        ]
                   [ 26.0  92.6   12.3  196 ]
(%o4)              [                        ]
                   [ 25.0  98