[FieldTrip] Problem running tutorial

Fri Aug 23 08:06:01 CEST 2019

Dear Dan,

Sorry for the trouble. It is surprising (somewhat) that you get this error. Although I agree with Stephen, that using a more recent Matlab version would certainly work, but there are some checks and balances in fieldtrip that are aimed to prevent this backward compatibility issue that you encounter. Long story short: for ’newer’ matlab functions we provide overloaded versions of the same functions, which are to be used when a matlab version is used that pre-dates the introduction of the newer mathworks based functions.
This should be automatically handled by a section in ft_defaults (starting from line 217 or so), where, based on the matlab version used, a set of ‘compat’ directories is added to the matlab path, which points to the relevant folders that contain the overloaded functionality. Somehow, in your setup this fails, and it fails silently, due to the ’try/catch/end’ statement that is around this block of code.
So in order to get a better handle on this, you probably need to uncomment the ’try’ and its corresponding ‘end’, which would allow matlab to output an error message when calling ft_defaults. If you make the changes to ft_defaults, and then do the following on the matlab command line

restoredefaultpath;
ft_defaults;

Then at least you will get an error message (probably) that indicates why the automatic addition of the relevant folders to the path does not work for you.

Another possibility would be to just add manually to the matlab path the folders that are needed, i.e. all fieldtrip/compat/matlabltX folders, where X is anything more recent than the version of matlab that you are using.

Hope this helps and with best wishes,

Jan-Mathijs

PS: just as a side note I recommend not to put the fieldtrip-folder in the MATLAB application’s toolbox directory, just to keep a clear distinction between the stuff that comes from Mathworks, and the code that comes from external parties (such as the fieldtrip team).

On 23 Aug 2019, at 00:36, Stephen Whitmarsh <stephen.whitmarsh at gmail.com<mailto:stephen.whitmarsh at gmail.com>> wrote:

Dear Dan,

Yes, its your old matlab version; isfolder is a later MATLAB function. Can you get yourself an upgrade? Usually, your license will permit that, or your university would be able to do so. Matlab has improved a lot since, and in and case it will be increasingly difficult to keep things backwards compatible.

Cheers,
Stephen

On Thu, 22 Aug 2019, 22:59 Dillon, Daniel G., <ddillon at mclean.harvard.edu<mailto:ddillon at mclean.harvard.edu>> wrote:
Hi everyone. I’m new to FieldTrip and am excited to try it but I can’t get the tutorials started. I’ve downloaded fieldtrip-20190819 and I’m running MATLAB_R2015b. I’m trying to run the “Trigger-based trial selection tutorial” (http://www.fieldtriptoolbox.org/tutorial/preprocessing/), but when I type “ft_definetrial(cfg)” in MATLAB it returns the long error pasted at the end of this email. It looks like there is a problem with the “isfolder” function, and since the warning message points me to the documentation about setting paths (http://bit.ly/2SPPjUS), I also tried re-setting everything by typing this . . .

>> restoredefaultpath
>> addpath /Applications/MATLAB_R2015b.app/toolbox/fieldtrip-20190819/
>> ft_defaults

. . . but I get the same error message. I think this may be a backwards compatibility issue but I’m not sure how to troubleshoot it. Can anyone point me in the right direction?

Thanks!

Dan Dillon
McLean Hospital

          Here’s the error message:

          Warning: removing
"/Applications/MATLAB_R2015b.app/toolbox/fieldtrip-20190819/compat/matlablt2017b" from your path,
see http://bit.ly/2SPPjUS
> In isfolder (line 21)
  In ft_version (line 64)
  In ft_preamble_init (line 50)
  In ft_preamble (line 83)
  In ft_definetrial (line 128)
Error using feval
Undefined function 'isfolder' for input arguments of type 'char'.

Error in isfolder (line 27)
    [varargout{1:nargout}] = feval(mfilename, varargin{:});

Error in ft_version (line 64)
  issvn = isfolder(fullfile(ftpath, '.svn'));

Error in ft_preamble_init (line 50)
[FjmoT6aA_ft_ver, FjmoT6aA_ft_path] = ft_version;

Error in ft_preamble (line 83)
evalin('caller', full_cmd);

Error in ft_definetrial (line 128)
ft_preamble init

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