This collection of programs and modules, written in C, is intended to
support research and education concerning Low Density Parity Check
(LDPC) codes.  (Note, however, that the copyright notice no longer
restricts use to these purposes).  These codes were invented by Robert
Gallager in the early 1960's, and re-invented and shown to have very
good performance by David MacKay and myself in the mid-1990's.  The
decoding algorithm for LDPC codes is related to that used for Turbo
codes, and to probabilistic inference methods used in other fields.
Variations on LDPC and Turbo codes are currently the best practical
codes known, in terms of their ability to transmit data at rates
approaching channel capacity with very low error probability.