The formula of four factors is given in analyzing first - order circuits , the initial value is extend as far as 0 _ value and it is unanimously agreed other theory of circuit analysis 摘要給出了直流激勵下的一階電路的四要素公式,將經典分析的起點延伸到0 _ ,使經典電路分析與現代電路分析的起點一致,統一了動態分析理論。