STFT相关函数，包含了源代码，说明和简单的例子。-STFT related functions, including the source code, descr iptions and simple examples.

stft的几个例子，包括对同一信号输出其等高线图、三维频谱图等，对于初学者很有帮助。-stft several examples, including the same right to export its signal contour maps, three-dimensional map of the spectrum. useful for beginners.