perform the Durbin test for balanced incomplete block design

利用均衡不完全区组设计(Balance Imcomplete Block Designs，BIBD)的半结构化低密度奇偶校验(Low Density Parity Check，LDPC)码设计方法。可以生成仿真结果曲线-The use of a balanced incomplete block design (Balance Imcomplete Block Designs, BIBD) semi-structured Low Density Parity Check Codes design