研究自傅里叶函数的构造法则，给出了和Ｃａｏｌａ的法则互为补充的法则：ｆ（ｘ）＝ｇ（ｘ）ｇ（－ｘ）＋ｇＦ（ｘ）＊ｇＦ（－ｘ）。分析了它的优缺点。最后，导出了构造自傅里叶函数法则的最简表达式 Studying the construction rule of Fourier function, we give the rule of complementing Caola’s law: f (x) = g (x) g (-x) + gF (x) * gF (-x). Analyze its advantages and disadvantages. Finally, the simplest expression constructed from Fourier’s law is derived