Tadashi Wadayama Masayuki Yagita Yuuki Funahashi Shogo Usami Ichi Takumi Gradient Descent-Bit Flipping Algorithms for Decoding LDPC Codes http://arxiv.org/abs/0711.0261 2007 CoRR abs/0711.0261 db/journals/corr/corr0711.html#abs-0711-0261 informal publication