 class="keyword">typename</span> StateIn<span class="special">,</span> <span class="keyword">typename</span> DerivIn<span class="special">,</span> 
           <span class="keyword">typename</span> StateOut<span class="special">&gt;</span> 
    <span class="keyword">void</span> <a class="link" href="modified_midpoint.html#idm28709-bb"><span class="identifier">do_step_impl</span></a><span class="special">(</span><span class="identifier">System</span><span class="special">,</span> <span class="keyword">const</