I should mention that there are some interesting new features in Python
2.2, and you can read about them at http://www.python.org. Of particular
interest to those of us doing scientific computations is the following
example:
from __future__ import division # two underscores before and after
"future"
print 3/2
The result is 1.5, whereas without the "from" statement the result is 1.
The intent is that with Python 3.0, some time in the future, this behavior
of division will be standard, but you can import this behavior "from the
future" right now. Also as of Python 2.2 if you want the old "integer
division" behavior you can us two slashes: 3//2 gives 1. People are
encouraged slowly to change to the new syntax. There will be a warning
mechanism you can invoke that will tell you of any existing integer
division cases, so you can decide whether to replace "/" with "//".
This change to Python was prompted in part by observations that novice
programmers often make the mistake of writing 3/2 when they thought they
would get the behavior of 3.0/2.0. This was one of the few significant
problems our own physics students have had with Python syntax, and it's
often hard to track down the source of the problem when a program
malfunctions due to this. Frankly, it's a mistake that experienced
programmers also make sometimes when doing scientific computations.
Bruce Sherwood
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