&lt;</span> <span class="identifier">endl</span><span class="special">;</span>
</pre>
<p>
        </p>
<p>
          The second iterator type is also a iterator with const step size. But the
          value type of this iterator consists here of a pair of the time and the
          state of the solution of the ODE. An example is
        </p>
<p>
</p>
<pre class="programlisting"><span class="identifier">runge_kutta4</span><span class="special">&lt;</span> <span class="identifier">state_type</span> <span clas