STFTDifference

代码说明：

  短时傅里叶变换可以用差分模式来实现，对书上的运算式做了稍许的改变。改变-计算差分序列的第一列数据时用的是第一列的元素减去当前行的最后一列元素。原算法中采用的是第一列元素减去下一行第二列元素。原算法加窗之后结果比较好，不加窗时结果误差很大，而改变之后的算法不加窗效果依然很好。(Short time Fourier transform can be used to achieve the differential mode of expression on the book made a slight change. Change- calculating the difference sequence of the data with the first column is the first column of the matrix by subtracting the current element in the last column of row. Is used in the original algorithm subtracts the elements of the first column of the next row and the second column elements. After the results of the original algorithm windowed better, when the results window without great error, and after changing algorithms no window effect is still very good.)