# File lib/rufus/scheduler/cronline.rb, line 278
    def brute_frequency

      key = "brute_frequency:#{@original}"

      delta = self.class.cache[key]
      return delta if delta

      delta = 366 * DAY_S

      t0 = previous_time(Time.local(2000, 1, 1))

      loop do

        break if delta <= 1
        break if delta <= 60 && @seconds && @seconds.size == 1

#st = Time.now
        t1 = next_time(t0)
#p Time.now - st
        d = t1 - t0
        delta = d if d < delta
        break if @months.nil? && t1.month == 2
        break if @months.nil? && @days.nil? && t1.day == 2
        break if @months.nil? && @days.nil? && @hours.nil? && t1.hour == 1
        break if @months.nil? && @days.nil? && @hours.nil? && @minutes.nil? && t1.min == 1
        break if t1.year >= 2001

        t0 = t1
      end

      self.class.cache[key] = delta
    end