fwt,fwt2分别是一维、二维快速沃尔什变换函数,采用蝶形快速算法编写，要比利用矩阵相乘得到变换结果的离散沃尔什变换快很多-fwt, fwt2 are one-dimensional, two-dimensional fast Walsh transform function, the use of butterfly Fast Algorithm for the preparation of, than the use of transformation matrices to be the