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David Coutinho received the B.S. degree in electronics and telecommunications engineering from ISEL (Polytechnic Institute of Lisbon) in 1990, the Electrical Engineer degree from ISEL in 1993, and the M.S. degree in electrical and computer engineering from IST (Technical University of Lisbon) in 1997. He worked as a research engineer for SIBS (Sociedade Interbancária de Serviços SA) from 1990 to 1996, where he was involved in the design and engineering development of electronic funds transfer systems. In 1995 joined the Department of Electronics and Communications Engineering at the ISEL as a lecturer and also as a researcher. His research interests include signal processing, data compression and cryptography.
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Test results of Bzip2, Gzip and Pkzip with the Calgary corpus: respectively 2,48981 bits/char, 2,80894 bits/char e 2,83500 bits/char (average values).
Related articles:
- M. Burrows and D.J. Wheeler, "A Block-sorting Lossless Data Compression Algorithm", Digital Systems Research Center Research Report 124, May 1994.
- M. Nelson, "Data Compression with the Burrows-Wheeler Transform", Dr. Dobb's Journal, September 1996.
Example: the BW transform of the file bertrand.txt is in the file bertrand.bwt; assuming independence of the symbols, the estimated entropy of the files is H(X)=4,000767 bits/char and H(X)=4,002213 bits/char respectively; assuming that each symbol depends only from the previous, the estimated entropy is H(X)=3,622171 bits/char and H(X)=3,218471 bits/char respectively.
Copyright (C) 1998 David Pereira Coutinho
Última actualização: 04-09-2002