使用MATLAB函数中的FFT命令计算离散时间信号的频谱，以加深对离散信号的DFT的理解及其FFT算法的运用。-using MATLAB function FFT calculation order discrete-time signal spectrum, to increase the discrete signals in the DFT and FFT algorithm understanding of the application.

matlab读取数据文件，进行fft，再写入数据文件，最后比较变化。-matlab to read data files for fft, and then write the data file, and finally compare changes.