[Visualpython-users] VPython for Python 2.1 on Windows

[Bruce S. <ba...@an...>]

At http://cil.andrew.cmu.edu/projects/visual you can now download VPython 
for Python 2.1 on Windows.

Paul Dubois and Dave Scherer diagnosed the problem we were having with 
Python 2.1, and David Andersen recompiled. Thanks, guys.

The new package no longer overwrites the standard IDLE but creates another 
folder Tools/idle_VPython and shortcuts on the desktop and the start menu 
that point to it. Users also have access to the standard IDLE from the 
start menu.

There is a new demo program, doublependulum.py, which shows chaotic motion 
in a simple system.

The minor source changes to Visual have not yet been checked in to 
sourceforge. They consist essentially of replacing tests such as "a == 
None" with "a is None". Python 2.1 introduced "rich comparisons" to satisfy 
users of Numeric who wanted to do more than test whether one array was 
equal to another. They wanted instead to be able to get an array of true 
and false results for element-by-element comparisons. They also wanted to 
be able to do other comparisons (<, >, etc.). This had a side effect which 
made "a == None" illegal if a is a Numeric array

Bruce Sherwood