d">return</span> <span class="number">0</span><span class="special">;</span>
<span class="special">}</span>
</pre>
<p>
          </p>
<p>
            Output:
          </p>
<pre class="programlisting">envelope:((2, 0.7), (5.4, 3))

<img src="../../../../img/algorithms/envelope.png" alt="envelope">
</pre>
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