At 13:31 31/03/2005, you wrote:
>Currently a DCM parameter estimation is running on my computer.
>It runs for 24 hours now, and there is no output visible on the matlab screen.
>The Matlab task continously uses variable CPU resources between 40-60% (P
>IV, 2500MHz).
>Working memory is sufficent to not activate swapping.
>It runs on Windows XP Pro, Matlab 6.5.1 with the -nojvm option.
>
>I installed the newest DCM Patches from SPM Updates. Even fount the
>spm_logdet definition
>in the Mailing list archives. Besides ... it would be nice to add the
>spm_logdet.m to the ftp
>directory.
>
>Model Size:
>1560 Scans, 2mm Voxel Size, 5 ROI's with a radius of 6mm.
>4 Regressors modulating 10 connections.
>
>There were no problems at all with simpler models, even not with a 5 ROI
>Model, but only
>4 modulated connections, 6 at all. Also 4 Regressors, a pair of modulating
>two connections.
>
>Has it crashed?
>
>------------------------------------------------------------
>Ferenc Acs
>Lehrstuhl Prof. Dr. M. W. Greenlee
>Institut für Psychologie
>Universität Regensburg
>93040 Regensburg
>Tel. +49 (0)941 943 3582
>Fax +49 (0)941 943 3233
>http://www.psychologie.uni-regensburg.de/Greenlee/team/Acs/acs.html
Dear Ferenc,
your model is probably at the limits of MATLAB memory handling. Note that
within DCM the time series from the various VOIs are combined into a single
data vector so that for N regions with S scans each you have a SxN data
vector. The resulting covariance matrices thus become huge for many scans
and/or regions.
With MATLAB6 I remember seeing problems for approx. SxN>6000 (in your case:
SxN>7500). As I have not worked with version 7 yet, I don't know whether
this has changed with MATLAB7.
Thanks for reminding me that spm_logdet was missing in the updates
directory. I will put it there asap.
Very best wishes,
Klaas
_____________________________________
Dr Klaas Enno Stephan
Wellcome Dept. of Imaging Neuroscience
12 Queen Square, WC1N 3BG, London, UK
phone: +44-207-8337485
fax: +44-207-8131420
web: http://www.fil.ion.ucl.ac.uk/~kstephan/
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