# File hbody.rb, line 87
  def hermite(dt)
    old_pos = @pos
    old_vel = @vel
    old_acc = acc
    old_jerk = jerk
    @pos += @vel*dt + old_acc*(dt*dt/2.0) + old_jerk*(dt*dt*dt/6.0)
    @vel += old_acc*dt + old_jerk*(dt*dt/2.0)
    @vel = old_vel + (old_acc + acc)*(dt/2.0) + (old_jerk - jerk)*(dt*dt/12.0)
    @pos = old_pos + (old_vel + vel)*(dt/2.0) + (old_acc - acc)*(dt*dt/12.0)
  end