说明：  我编写的利用trous（多孔算法）实现小波变换，利用‘db4’小波函数分解两层，其中卷积运算采用频域的fft算法，给出了仿真信号的处理结果。
(prepared by the use of trous (porous algorithm) to achieve wavelet transform, use 'db4' wavelet decomposition layers, which used convolution operators fft the frequency domain algorithm, given the signal processing simulation results.)