26 June 2023

This site provides the current version of the first edition of the book Entropy and Information Theory by R.M. Gray in the Adobe portable document format (PDF). This format can be read from a Web browser by using the Acrobat Reader helper application, which is available for free downloading from Adobe.

The current version is a corrected version of previously posted corrected version of March 2013, which was a corrected and slightly revised version of the second printing (1991) of the Springer-Verlag book of the same name, which is now out of print. In 2023 further typos and other corrections were made, including correcting proofs of the entropy ergodic theory and the variational characterization of relative entropy. This corrected version is made available with the permission of Springer-Verlag. This will be the final version of the First Edition of the book, but I will continue to correct any typos or mathematical errors found by me or others. The Second Edition was published in 2011 by Springer. Errors of the First Edition which propagated to the Second Edition are corrected in the Errata for the Second Edition

Permission is hereby given to freely print and circulate copies of this book so long as it is left intact and not reproduced for commercial purposes. I welcome all typos and comments. Revised 3 June 2023.