傅立叶级数展开式直流项的计算问题

The Calculation of Direct Current Item in Fourier Series Expression

在连续周期信号的傅立叶级数展开式中,很多文献普遍采用a0=an|n=0和c0=cn|n=0来计算a0和c0,间接得到其直流项。本文用一些具体例题分析说明了上述做法的矛盾,得出结论:用傅立叶级数法计算直流项在一些情况应该使用a0和c0各自独立的计算公式,而不应该用an和cn代入零来进行计算。

In Fourier series expression of continuous signals, ao and co are generally calculated by me tormulas of no=an ｜n=0 and c0 =cn ｜ n=0in many books. Direct current item is enumerated through a0 and co indirectly. Some kinds of contradictions in upper method are analyzed by some examples. The conclusion is that the direct current item of Fourier series should be calculated by the formulas of a0 and co of their own in some instances.