Sheil--Small[1] discussed the Fourier series of a step function while thisthesis implements a detailed discussion and illustration on the properties of the step func-tions concerned in [1].

• Sheil-Small [1]讨论了阶梯函数的Fourier级数。 本文对[1]中所涉及到一些阶梯函数的性质进行了详细讨论,并给出了详细证明。