Hi Shan and SnPMers,
At 07:35 PM 2/23/2005 +0000, Shan Shen wrote:
>I got a problem when "Compute" in SnPM2b.
>My data is 2 group, grey matter structural images. Only 5 subjects in each
>group. However, it always gives me an error message "Out of Memory".I
>already set the virtual memory to 4GB and there are only 600M variables in
>the workspace of MATLAB. I don't know if it is really the memory problem
>as most VBM analysis invovles much more data than that. Any suggestion
>would be helpful!
My guess is that SnPM2b simply ran out of memory because it tried to do the
calculation in the volumetric mode, as oppose to the slice-by-slice mode
which is more memory-efficient. Unfortunately SnPM2b only gives you the
choice between the volumetric or slice-by-slice mode if you have more than
16 images in the data set. If you have a small number of images (n <= 16
images), then it tries to run the analysis in the volumetric mode by
default. I see this is a problem in a VBM data analysis, where each image
is large and you want to conserve memory.
A quick and easy solution I can suggest is that you change line 247 in
snpm_ui.m to
nMax4DefVol=9;
By changing this line, you will be given a choice between the volumetric or
slice-by-slice mode if you have more than 9 images (instead of default 16).
Run the "Setup" again before you run the "Compute". During the Setup,
answer "No" to "Work volumetrically".
I hope this works, but if it doesn't, there is a possibility that you
really don't have enough memory.
-Satoru
Satoru Hayasaka ==============================================
Post-Doctoral Fellow, MR Unit, UCSF / VA Medical Center
Email: shayasak_at_itsa_dot_ucsf_dot_edu Phone:(415) 221-4810 x4237
Homepage: http://www.sph.umich.edu/~hayasaka
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