[Eeglablist] Singular matrix error for Laplacian plugin
josep.marco at starlab.es
Tue Mar 2 11:43:16 PST 2004
I also agree (I'd made the plugin). The plugin was tested with a 30 electrodes configuration and Dr Delorme made some modifications and sent me, but I've had no time to upload the version (I'll make it in the future to the web page). The plugin worked with our configuration but we didn't tested more (we focused our atention in the Spherical Harmonics Expansion, SHE). So I'll made corrections and when it would be operative I'll inform to Eeglablist.
----- Original Message -----
From: Arnaud Delorme
To: Scott Laurence Fairhall
Cc: eeglablist at sccn.ucsd.edu
Sent: Tuesday, March 02, 2004 6:10 PM
Subject: Re: [Eeglablist] Singular matrix error for Laplacian plugin
I agree. This plugin is not stable (you are talking about the plugin available on this web page I guess http://220.127.116.11/fbos/projects/kolmogorov.html). I tried to use it and after intense debugging, I still had some conceptual problem (even when I used a high degree of spherical harmonic expansion, I obtained topographic plots that did not totally resemble the classical topoplots (they had some strong similarities and strong dissimilarities)), so there might still be a problem? I can send the edited version of the plugin to whoever is interested (I sent it to the author so he could update his web site with a functional version but he probably did not have time to do it).
Scott Laurence Fairhall wrote:
when I attempt to use the lap_perrin function contained within the EEGLAB laplacian
plugin I receive an error. When matlab attempts to inv(mat) where mat is (i think!) some
form of spline I get a message saying my matrix is badly scaled or singular (and
therefore has no inverse).
Does anyone have any suggestions about what it is in my electrode coordinates that
may cause this to arise?
Research Centre for Cognitive Neuroscience
Department of Psychology
University of Auckland
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Arnaud Delorme, Ph.D.
Computational Neurobiology Lab, Salk Institute
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