Dear Antanas,
I assume you are talking about DCM for ERP. Since the graphics window
has limited area, the graphic display indeed breaks down at some point
if you have too many sources. This is not, however, a limitation of
the actual DCM. From the point of view of the code, it is only limited
by your computer's number crunching abilities, but from the point of
view of common sense there is a limit to how many sources you can put
in a reasonable ERP model, especially with small number of channels.
If your models are more complicated than your data can support, you
will usually not get significant differences in model comparison or
you will get that the simplest model is the best because all the
others have been penalized due to their complexity.
In your case, although the connectivity matrices cannot be displayed
properly, they are all in the DCM structure which you can find in the
.mat file which is saved by DCM and also in the workspace once DCM
finishes running. A good way to decipher the meaning of the different
fields of the structure is by putting a breakpoint in
spm_dcm_erp_results and getting to the part of the code which
generates the figure with the thing you are interested in. By
examining this code you can figure out how that thing is computed from
what is stored in the DCM struct and do the same in your code.
The free energy (which approximates the log evidence), for instance,
is stored in DCM.F
Best,
Vladimir
On Fri, Jun 12, 2009 at 10:45 AM, Spokas
Antanas<[log in to unmask]> wrote:
> Hey all,
>
> I have tried to model 5 pairs of sources in my DCM, but in GUI it looks like
> its not possible, as for instance matrix C desapears (no room it seems), its
> fine with 4 pairs (8 all together). Is there a max number in DCM and if it
> is what is literature reference, please?
> I have also failed to find a model log evidence number for specific model,
> as when using BMS batch, it only gives a relative comparison, where can I
> get the actual figure?
> Thank you so much!!!!!!
>
> Regards,
> Antanas
>
>
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