neuromag data analysis

[Virginie van Wassenhove]

Hello Fieldtrip-ers and happy new year!

I am trying to get some Neuromag (MEG) data analysis done with Fieldtrip - so
far I had used fieldtrip for EEG. I can read the data fine (segmentation via
meg-pd) but there are a couple of issues now.

1. when I try to filter or downsample I am receiving the following errors: 

%FILTER (lpf specified in cfg)
blah = timelockanalysis(cfg,data_std_bc);
the input is timelock data with 306 channels and 801 timebins
applying preprocessing options
??? Undefined function or method 'butter' for input arguments of type 'double'.

Error in ==> preproc_lowpassfilter at 80
    [B, A] = butter(N, max(Flp)/Fn);

Error in ==> preproc at 360
if strcmp(cfg.lpfilter, 'yes'),     dat = preproc_lowpassfilter(dat,
fsample, cfg.lpfreq, cfg.lpfiltord,
cfg.lpfilttype, cfg.lpfiltdir); end

Error in ==> timelockanalysis at 318
  [data.trial{i}, data.label, data.time{i}, cfg.preproc] =
preproc(data.trial{i}, data.label,
  data.fsample, cfg.preproc, data.offset(i));
=================================
%RESAMPLE
??? Error: File: isequal.m Line: 1 Column: 1
The input character is not valid in MATLAB statements or expressions.

Error in ==> checkdata at 145
if ~isequal(feedback, 'no')

Error in ==> resampledata at 60
data = checkdata(data, 'datatype', 'raw', 'feedback', 'yes');

=================================
The data structure looks fine to me:

data_dev1 = 
        hdr: [1x1 struct]
      label: {306x1 cell}
      trial: {1x101 cell}
       time: {1x101 cell}
    fsample: 1000
       grad: [1x1 struct]
        cfg: [1x1 struct]

data_dev1.grad =
      pnt: [510x3 double]
      ori: [510x3 double]
      tra: [306x510 double]
     unit: 'cm'
    label: {1x306 cell}


Any idea on these error messages?

2. The second issue is that doing a timelockanalysis on these data returns
no neg or pos clusters. There is no error message and the computations seem
to run fine.

Am I missing some steps in the preliminary stages of data analysis for MEG
in fieldtrip?

Thanks for any help you may provide,

Virginie

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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.