Dear Diane,
The error might have something to do with the fact that the montage
matrix you used is wrong. To do what you intended you'd need the
transpose of what you specified, but as I mentioned to be on the safe
side it'd be better to convert the data to average reference. In your
case of a 64 channel system you'd need something like:
tra = eye(64) - ones(64)/64;
for the EEG channels (or if you have 65, the same with 65).
Best,
Vladimir
On Tue, Jun 16, 2009 at 12:37 PM, Diane Whitmer<[log in to unmask]> wrote:
> Dear SPMers,
>
> I am using SPM8 with EEG data. When I try to compute the Inverse solution, I
> get the following error message:
>
> Warning: Matrix is singular, close to singular or badly
> scaled.
> Results may be inaccurate. RCOND = NaN.
>
>
> Does anyone have suggestions for how to debug this?
>
> A subset of these data previously worked for computing an Inverse Solution.
> One difference with my current dataset is that I have re-referenced to one
> of the EEG channels (because it's not clear that SPM selects a reference
> channel when importing from Biosemi). This may or may not be related to the
> problem I'm having.
>
>
> Thank you,
> --
> Diane Whitmer, Ph.D.
> Researcher in Applied Neuroscience
>
> C. de l' Observatori Fabra s/n
> 08035 - Barcelona - Spain
> tel. +34 93 254 03 68
> fax. +34 93 212 64 45
> skype. dwhitmer
> email. [log in to unmask]
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