>deriv_type</span>                            <a name="boost.numeric.odeint.runge_kutta4_classic.deriv_type"></a><span class="identifier">deriv_type</span><span class="special">;</span>       
  <span class="keyword">typedef</span> <span class="identifier">stepper_base_type</span><span class="special">::</span><span class="identifier">time_type</span>                             <a name="boost.numeric.odeint.runge_kutta4_classic.time_type"></a><span class="identifier">time_type</span><span class="special">;