span><span class="keyword">void</span><span class="special">)</span><span class="special">;</span>
  <span class="keyword">const</span> <span class="identifier">state_type</span> <span class="special">&amp;</span> <a class="link" href="dense_output_r_idp20189216.html#idp20212512-bb"><span class="identifier">get_old_state</span></a><span class="special">(</span><span class="keyword">void</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  <span class="ident