中文说明：常用的特征提取方法hog，sift等matlab写的，可以作为新手参考。用于模式识别常用的一些信号特征提取的方法。写模式识别的人可以参考下。
English Description：
Commonly used feature extraction methods, such as hog, sift, are written in MATLAB, which can be used as a reference for novices. Some signal feature extraction methods commonly used in pattern recognition. Write pattern recognition can refer to the next.