回顾：连续周期信号的傅立叶级数 https://en.wikipedia.org/wiki/Fourier series Function s(x)(in red)is a sum of six sine functions of different amplitudes and harmonically related frequencies.Their summation is called a Fourier series The Fourier transform,S(f) (in blue),which depicts amplitude vs frequency, reveals the 6 frequencies (at odd harmonics)and their amplitudes(1/odd number). ·推荐：[知乎]傅里叶分析之掐死教程（完整版）https:zhuanlan.zhihu.comp/19763358回顾：连续周期信号的傅立叶级数 https://en.wikipedia.org/wiki/Fourier_series Function s(x) (in red) is a sum of six sine functions of different amplitudes and harmonically related frequencies. Their summation is called a Fourier series. The Fourier transform, S(f) (in blue), which depicts amplitude vs frequency, reveals the 6 frequencies (at odd harmonics) and their amplitudes (1/odd number). 8 • 推荐：[知乎] 傅里叶分析之掐死教程（完整版） https://zhuanlan.zhihu.com/p/19763358