/* * 题目：如果把明文字母按一定顺序排列成矩阵形式，用另一种顺序选择相应的列输出得到密文，如用“china”为秘钥，对”this is * a book mark“排成矩阵如下： * t h i s i * s a b o o * k m a r k */ -/** Topic: If the plaintext letters arranged in a matrix form according to a certain order, in an

LDPC encoder and the decoder of sum-product algorithm.(input H matrix form is Mackay s website form)