From the reviews of the second edition: "This book addresses primarily a CSE (computational science and engineering) audience. … gives a clear and detailed account on the ways in which the surprisingly powerful Python language may aid the CSE community." (H. Muthsam, Monatshefte für Mathematik, Vol. 151 (4), 2007)

The major change between the second and third editions, however, is
caused by the new implementation of Numerical Python, now called numpy. The new numpy package encourages a slightly different syntax compared to the old Numeric implementation, which was used in the previous editions. Since Numerical Python functionality appears in a lot of places in the book, there are hence a huge number of updates to the new suggested numpy syntax, especially in Chapters 4, 9, and 10.
The second edition was based on Pvthon version 2.3, while the third edition contains updates for version 2.5...