说明：   huffman编码生成器 函数说明： [W,L,q]=huffman(P) 为huffman编码函数 P为信源的概率矢量，W为编码返回的码字 L为编码返回的平均码字长度，q为编码效率
(Huffman encoding generated Function Description: [W, L, q] = huffman (P) P for the Huffman encoding function for the probability of the source vector, W is encoded back into the code word L coding for return The average code word length, q is the coding efficiency )