gns <code>b</code> to be a vector equivalent to the first <code>N</code> elements of the vector <code>a</code>. The function <code>tail</code> works the same way for suffixes, with</p>
<pre><code>array[M] a = ...;
array[N] b = tail(a, N);</code></pre>
<p>Finally, there is a segment function, which specifies a first element and number of elements. For example,</p>
<pre><code>array[15] a = ...;
array[3] b = segment(a, 5, 3);</code></pre>
<p>will set <code>b</code> to be equal to <code>{ a[5], a[6], a[7] }</co