# File lib/powerbar.rb, line 197
  def update(opts={})
    state.merge!(opts)
    state.time_start ||= Time.now
    state.time_now = Time.now

    @rate ||= PowerBar::Rate.new(state.time_now, 
                                 state.settings.rate_sample_window,
                                 state.settings.rate_sample_max_interval)
    @rate.append(state.time_now, state.done)
  end