中文说明：
区别去传统的傅里叶变换，对于非平稳信号而言，分数傅里叶变换是一个较好的方法，本程序实现了分数傅里叶变化对LPF类信号的估计。具有较高的学习价值。
English Description：
Different from the traditional Fourier transform, fractional Fourier transform is a better method for non-stationary signals. This program realizes the estimation of LPF signals by fractional Fourier transform. It has high learning value