[Mne_analysis] issue with inverse operator (repost)

[Hari Bharadwaj]

Hi Ricky,
   One possibly useful test to see if the issue is related to machine
precision/round-off related bugs is to apply the inverse operator in
MATLAB at double precision using mne_ex_compute_inverse().

If that works fine, then it probably confirms a bug with mne_make_movie.
If that also looks weird, then it could potentially point to something
more upstream such as  the SSP (that's used on the data) not being applied
to the lead field/noise covariance correctly etc..

Regards,
Hari



On Mon, June 6, 2011 3:57 pm, Eric Larson wrote:
> Assuming you are running linux (are you?), were you able to test it on
> both x86_64 and i686 versions?
>
> Eric
>
>
> On Mon, Jun 6, 2011 at 12:52 PM,  <rsachdev at nmr.mgh.harvard.edu> wrote:
>> Hello Eric,
>>
>> We tried the stable release and the nightly build.  The stable release
>> inverse operator seems to work fine but than the issue with the
>> projection
>> vectors exists.  With the nightly build, it's the opposite, the inverse
>> operator gives me the issue and there seems to be no problem with the
>> EEG
>> and MEG projection vectors.
>>
>>
>>
>>
>>
>>> I had a problem with the EEG projection vectors affecting MEG channels
>>> as well. However, it only happened on my linux x86_64 install, not on
>>> a linux i686 install or osx installs. As you note, this channel
>>> corruption on x86_64 was fixed in a recent nightly. I assume, then,
>>> that you're running the linux x86_64 nightly?
>>>
>>> If so, one thing you could try is generating your inverses using all
>>> four combinations of 1) the last stable release and 2) the latest
>>> nightly combined with 1) the x86_64 linux version and 2) the i686
>>> linux version. (The i686 linux version should run just fine on 64-bit
>>> linux installs.) If you can identify which of the four combinations
>>> suffers from this problem, then it could help narrow down the cause of
>>> the problem.
>>>
>>> Eric
>>>
>>>
>>> On Fri, Jun 3, 2011 at 9:39 AM,  <rsachdev at nmr.mgh.harvard.edu> wrote:
>>>> Hi all,
>>>>
>>>> It's been a few weeks, and I am still having trouble with this.
>>>>
>>>> There seems to be an issue with the inverse operator from the nightly
>>>> build version of MNE.  The activation shown on the brain looks unusal.
>>>>  I
>>>> am using the nightly build because in the previous versions working
>>>> with
>>>> SSP for EEG affected the MEG channels and it was fixed in the nightly
>>>> build.  Now, I seem to be running into some trouble when using an
>>>> inverse
>>>> operator created from both MEG and EEG data, the MEG based inverse
>>>> operator works/looks fine.  Anyone have any work-arounds or solutions?
>>>>
>>>> Thank you
>>>> -Ricky
>>>>
>>>>
>>>>
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>>
>>
>
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-- 
Hari Bharadwaj