[FieldTrip] Sign flip in lcmv spatial filter with different versions of MATLAB

[Bushra Riaz Syeda]

Hello,

I am having a strange error. I calculated lcmv beamformer for my  Neuromag dataset couple of years ago. I ran some beamformer based analysis and now I thought I will redo some part of the analysis.
I noticed during the rerun of my scripts that the spatial filter calculated for 3 subjects ( out of 20) has a sign flip for 3-5 % of the vertices. After investigating for a week, I found that I get sign flip for these vertices when I run the same script with MATLAB 2013b and MATLAB 2017a ( fieldtrip version was same for both runs).

I have attached the figure for one of the vertex of spatial filter with both MATLAB versions.

Now my question is, as this sign flip is affecting my further analysis, I would like to know , how to figure out which one is correct and if anyone has any idea where the error could be coming from.
Thank you
Any help would be highly appreciated.

Kind regards
Bushra Riaz

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