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.

• 摘要给出了直流激励下的一阶电路的四要素公式，将经典分析的起点延伸到0_，使经典电路分析与现代电路分析的起点一致，统一了动态分析理论。