在LDPC码的校验矩阵中，环4的存在对码的性能影响是非常大的，本程序就是校验校验矩阵中是否存在环4，MATLAB编写的-In the LDPC code parity matrix, the ring 4, the existence of the performance impact of code is very large, this procedure is checking whether there is parity matrix ring 4, MATLAB prepared