Re: [Visualpython-users] Errors running Vpython on OSX

[Steve S. <st...@sp...>]

This sounds like the problem I saw when trying to run outside the Idle 
environment. Are you running inside Idle?

-steve

On Friday, October 4, 2002, at 04:19  PM, Chris Burns wrote:

> Hi all.
>
> Thanks for the quick reply!  To clarify, the script I ran was the 
> standard
> doublependulum.py that ships with the software.  It works fine on my 
> Linux
> computer (as well as other scripts I've written).  I've tried 
> installing
> VPython on two seperate Macs and get the same behaviour on both.  
> Details:
>
>   - Mac OSX 10.1.5
>   - python 2.2.1 installed using fink version 0.4.1
>   - Installed VPython (Visual-2002-07-22) using the install script
>
> Regarding the theta1 suggestion, the script sometimes bombs even before
> the pendulum completes an oscillation, so I don't think it's a problem 
> with
> theta becoming too large.  It does seem to have something to do with 
> the
> number of computations, though.  I wrote a double-pendulum of my own 
> with
> Runga-Kutta and it consistently dies more quickly.
>
> Unfortunately, I don't maintain the Mac's, I just installed fink to get
> python working, so I don't know if there might be some esoteric 
> software
> that might interfere.  But fink seems to make its own little world 
> below
> /sw, so I don't see how there could be a conflict.
>
> I also tried installing python from source (ie., not using fink) and I 
> get
> the same problem.
>
> Chris
>
>> doublependulum.py is part of the standard VPython demo suite. All the 
>> demos
>> work on other OSX machines.
>>
>> Bruce Sherwood
>>
>> ----- Original Message -----
>> From: "Andy Dougherty" <dou...@la...>
>> To: "Bruce Sherwood" <bas...@un...>
>> Cc: "Andy Dougherty" <dou...@ma...>;
>> <cb...@sw...>; <vis...@li...>
>> Sent: Friday, October 04, 2002 3:20 PM
>> Subject: Re: [Visualpython-users] Errors running Vpython on OSX
>>
>>
>>> On Fri, 4 Oct 2002, Bruce Sherwood wrote:
>>>
>>>> This vague possibility would seem to be ruled out by the fact that 
>>>> these
>>>> programs run on other people's Mac OSX machines, with presumably the
>> same
>>>> math libraries, no?
>>>
>>> Not quite, unless I've misunderstood the original poster's question.
>>> Yes, Vpython runs fine on other people's Mac OS X machines, but I'm
>>> unclear if this particular script runs fine on other people's Mac OS 
>>> X
>>> machines.
>>>
>>>>>> Traceback (most recent call last):
>>>>>>   File "doublependulum.py", line 71, in ?
>>>>>>     atheta2 = -(A*atheta1+C*sin(theta1))/B
>>>>>> ValueError: unexpected math error
>>>
>>> What I'm imagining is that the user is simulating a (possibly damped,
>>> driven) double pendulum that might have swung over many many times, 
>>> so
>>> that theta1 and/or theta2 might be very large compared to 2 pi.  
>>> That's
>>> the sort of thing I've seen eventually lead to odd problems 
>>> elsewhere.
>>>
>>> Perhaps if the original script were posted, others could test it.
>>>
>>> --
>>>     Andy Dougherty dou...@la...
>>>     Dept. of Physics
>>>     Lafayette College, Easton PA 18042
>>>
>>>
>>
>>
>
>
>
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