实现stft变换，输出时域图，频域图，能量谱等信号分析图。-Stft achieve transformation, the output time domain diagram, frequency domain, the energy spectrum and other signal analysis chart.

短时傅里叶变换是一种基于窗函数的变换，短窗能够提供较好的时域解析度，长窗能够提供较好的频域解析度。-Short-time Fourier transform is a transform window function based on the short window in the time domain can provide better resolution, the long window can provide better resolution in the frequency d

很好一个学习傅里叶变化的程序说明，以及实例说明，对初学者有很大的帮助-Fourier transform a good learning program descr iption and examples illustrate, there is a great help for beginners