cannot convert gradiometer definition back to axial, please contact Robert (fwd)

[Sameer Walawalkar]

I think I was getting this message because I did not have
cfg.keeptrials = 'yes'

I am also trying without combineplanar as it seems that it might not be
required for NM306. (Also combineplanar  gives me same old error, "cant
convert gradiometer to axial. this is probably because, I did not go Axial
-> grad, so there is no point attempting grad->axial)


The current state of affairs is
cfg =

              channel: {306x1 cell}
               method: 'montecarlo'
            statistic: 'indepsamplesT'
         clusteralpha: 0.0500
     clusterstatistic: 'maxsum'
            minnbchan: 2
                 tail: 0
          clustertail: 0
                alpha: 0.0500
     numrandomization: 100
               design: [1 2]
                 ivar: 1
              latency: [0.2000 -0.1000]
            frequency: [8 14]
          avgoverchan: 'no'
          avgovertime: 'no'
          avgoverfreq: 'no'
           channelcmb: []
            precision: 'double'
              version: [1x1 struct]
             previous: {[1x1 struct]  [1x1 struct]}
               dimord: 'chan_freq_time'
                  dim: [306 7 1]

Using the gradiometer configuration from the dataset.
there are on average 17.4 neighbours per channel
using "statistics_montecarlo" for the statistical testing
??? Error using ==> fieldtrip/private/statistics_wrapper at 240
the size of the design matrix does not match the number of observations in
the data

Error in ==> freqstatistics at 106
[stat] = statistics_wrapper(cfg, varargin{:});

Error in ==> Auto_nonparametric_coh at 86
[stat_post] = freqstatistics(cfg, TFR_LL_200_400 , TFR_LL_neg1_neg2);



I shall be trying to troubleshoot this. Hope some of it makes sense.

thanks for your time.

best,
sameer




---------- Forwarded message ----------
Date: Thu, 14 Jun 2007 15:22:14 -0400 (EDT)
From: Sameer Walawalkar <sameer at andrew.cmu.edu>
To: FieldTrip discussion list <FIELDTRIP at NIC.SURFNET.NL>
Subject: Re: [FIELDTRIP] cannot convert gradiometer definition back to axial,
     please contact Robert


Hi,

As suggested I did freqanalysis and followd it up by trying combine planar and
got similar error.

cfgTFR = [];
cfgTFR.output       = 'pow';
cfgTFR.channel      = 'MEG';
cfgTFR.method       = 'mtmconvol';
cfgTFR.foi          = 5 : 5 : 90;
cfgTFR.t_ftimwin    = 5./cfgTFR.foi; cfgTFR.tapsmofrq    = 0.4 *cfgTFR.foi;
cfgTFR.toi          = .0 : 0.05 : .5;
cfgTFR.pad          =  'maxperlen';

and

cfg = [];
cfg.combinegrad = 'yes';

ERROR message:

the input is freq data with 306 channels, 18 frequencybins and 11 timebins
Warning: trying to convert planar to axial gradiometers, this is experimental
> In combineplanar at 280
   In Auto_nonparametric_coh at 47
??? Error using ==> combineplanar
cannot convert gradiometer definition back to axial, please contact Robert

Error in ==> Auto_nonparametric_coh at 47
TFR_LL_000_500_cmb = combineplanar(cfg, TFR_LL_000_500);


thanks,
sameer




On Mon, 11 Jun 2007, Robert Oostenveld wrote:

> Hi Sameer,
>
> On 7 Jun 2007, at 22:11, Sameer Walawalkar wrote:
>
>> Hello Robert,
>>
>> I have been playing around with
>> http://www2.ru.nl/fcdonders/fieldtrip/doku.php?id=fieldtrip:documentation:tutorial:statistics#3_permutation_tests_for_time-frequency_representations
>>
>> in an attempt implement non-paramteric statistical testing of coherence
>> diferences between trials. My screen currently reads:
>>
>> the input is freq data with 612 channels, 18 frequencybins and 11 timebins
>
> How did you manage to get 612 channels? Are you computing planar channels
> from your planar channels? Your neuromag system already has planar channels
> (by hardware design), hence you should not call megplanar on your data. The
> megplanar function is meant for computing planar gradients from a hardware
> magnetometer system (or a hardware axial gradiometer system, such as our
> CTF).
>
> After preprocessing and timelockanalysis or freqanalysis you should do
> combineplanar.
>
>> Warning: trying to convert planar to axial gradiometers, this is
>> experimental
>>> In combineplanar at 280
>>  In Auto_nonparametric_coh at 47
>> ??? Error using ==> combineplanar at 308
>> cannot convert gradiometer definition back to axial, please contact Robert
>>
>> Error in ==> Auto_nonparametric_coh at 47
>> TFR_LL_000_500_planar_cmb = combineplanar(cfg, TFR_LL_000_500_planar);
>>
>>
>> So, I am getting in touch with Robert Oostenveld.
>
> best regards,
> Robert
>
> ----------------------------------
> The aim of this list is to facilitate the discussion between users of the
> FieldTrip  toolbox, to share experiences and to discuss new ideas for MEG and
> EEG analysis. See also http://listserv.surfnet.nl/archives/fieldtrip.html and
> http://www.ru.nl/fcdonders/fieldtrip.
>

----------------------------------
The aim of this list is to facilitate the discussion between users of the FieldTrip  toolbox, to share experiences and to discuss new ideas for MEG and EEG analysis. See also http://listserv.surfnet.nl/archives/fieldtrip.html and http://www.ru.nl/fcdonders/fieldtrip.