fftAna

代码说明：

说明：  FFT（Fast Fourier Transformation）是离散傅氏变换（DFT）的快速算法 [1] 。即为快速傅氏变换。它是根据离散傅氏变换的奇、偶、虚、实等特性，对离散傅立叶变换的算法进行改进获得的。(FFT (Fast Fourier Transform) is a fast algorithm of discrete Fourier Transform (DFT). That is fast Fourier transform. According to the odd, even, imaginary and real characteristics of discrete Fourier transform, the algorithm of discrete Fourier transform is improved.)