重新审视一下矩阵H Theorem 8.7 Let H E Mmxn(Z2)be a canonical parity-check matrix.Then Null(H)consists of all x EZ3 whose first n-m bits are arbitrary but whose last m bits are determined by Hx=0.Each of the last m bits serves as an even parity check bit for some of the first n-m bits.Hence,H gives rise to an (n,n-m)-block code. 这意味着什么？ 记住：H=(A|Im) 间题11： 现在你“悟”到了什么吗？重新审视一下矩阵H 这意味着什么？ 记住：