LDPC codes BER simulation under AWGN channel. MacKay-Neal based LDPC matrix. Message encoding uses sparse LU decomposition. There are 4 choices of decoder: hard-decision/bit-flip decoder, probability-domain SPA decoder, log-domain SPA decoder, and simplified log-domain SPA decoder. Documentation and update can be found at:http://sites.google.com/site/bsnugroho/ldpc