o una lista de pares.
</p>
<pre class="example">(%i1) load (descriptive)$
(%i2) S: km([[2,1], [3,1], [5,0], [8,1]]);
                       charfun((3 &lt;= x) and (x &lt; 8))
(%o2) charfun(x &lt; 0) + -----------------------------
                                     2
                3 charfun((2 &lt;= x) and (x &lt; 3))
              + ------------------------------- 
                               4
              + charfun((0 &lt;= x) and (x &lt; 2))
(%i3) load (draw)$
(%i4) draw2d(
        line_width =