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From: "Roger Stafford" <ellieandrogerxyzzy@mindspring.com.invalid>
Newsgroups: comp.soft-sys.matlab
Subject: Re: Plot trajectories on a sphere?
Date: Wed, 9 Jan 2008 18:27:01 +0000 (UTC)
Organization: The MathWorks, Inc.
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roberson@ibd.nrc-cnrc.gc.ca (Walter Roberson) wrote in message <fm32q1
$rak$1@canopus.cc.umanitoba.ca>...
> In article <fm2ofj$evq$1@fred.mathworks.com>,
> Roger Stafford <ellieandrogerxyzzy@mindspring.com.invalid> wrote:
> >If you anticipate that x or y 
> >will have numbers outside the range you describe, you would first 
perform:
> 
> > x = mod(x+200,400)-200;
> > y = mod(y+200,400)-200;
> 
> >to do your "toroidal" thing.
> 
> If you have a vector that crosses the boundary, then would not
> taking the mod like that would result in a large jump back rather
> than in smooth crossing of the boundary?
-------
Yes, that worried me too, Walter.  It is to be hoped that in any given 
"trajectory" all the points would be shifted by mod in the same way.  I think 
we need a lot more clarification from Anil.

Roger Stafford