> i am now using optimized VBM script in spm2b. i have passed the first
> segmentation step. but something happened during the second segmentation
> step. the error shows "Matrix is singular to working precision" (In
> d:\spm2b\spm_segment.m (update_bp) at line 446, In D:\spm2b\spm_segment.m
> (run_segment) at line 346). i would like to know how i can solve this
> problem.
I think this one should be fixed by downloading the updates from:
http://www.fil.ion.ucl.ac.uk/spm/spm2b.html#Bugs2b
There have been a couple of fixes since the original release:
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spm_segment.m 2.18 02/12/11
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The mask defining which voxels are included in the computations now
checks for finite values.
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spm_segment.m 2.19 02/12/13
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There were problems with floating point images that were scaled to very
low intensities. Covariance estimates has a small amount added to them
to account for the precision of 8 bit or 16 bit data. This was derived
from the scalefactor. This was causing problems when low intensity
floating point images were segmented.
Best regards,
-John
--
Dr John Ashburner.
Functional Imaging Lab., 12 Queen Square, London WC1N 3BG, UK.
tel: +44 (0)20 78337491 or +44 (0)20 78373611 x4381
fax: +44 (0)20 78131420 http://www.fil.ion.ucl.ac.uk/~john
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