Overview of all Frequently Asked Questions

On this page you can find (and add) answers to a variety of Fieldtrip-related questions.

We invite you to add your own example scripts or frequently asked questions on the wiki. Also tutorials can be added. Every time you explain somebody something about Fieldtrip, please consider whether you could use the wiki for this so others can learn from it as well.

See also the tutorials and example scripts.

• What kind of dataformats can I read in?
• How can I import my own dataformat?
• How can I convert one dataformat into an other?
• How can I preprocess a dataset that is too large to fit into memory?
• Reading is slow, can I write my raw data to a more efficient file format?
• Why are the fileio functions stateless, does the fseek not make them very slow?
• How does the filter padding in preprocessing work?
• How can I process continuous data without triggers?
• What kind of filters can I apply to my data?
• How can I consistently represent artifacts in my data?
• How can I read corrupted (unsaved) CTF data?
• I have problems reading in neuroscan *.cnt files. How can I fix this?

• Is it possible to keep track of trial-specific information in my FieldTrip analysis pipeline?
• I used to work with trl-matrices that have more than 3 columns. Why is this not supported anymore?
• What is the format of the layout file, which is used for plotting?
• What is the difference between coherence and coherency?
• What is the idea behind statistical inference at the second-level?
• I am getting strange artifacts in figures that use opacity
• I am having problems reading the CTF *.hc headcoordinates file
• Why does my TFR contain NaNs?
• Why does my TFR look strange?
• Why does my ICA output contain complex numbers?
• Can I get an offline version of the wiki documentation?
• How can I determine the anatomical label of a source?
• Can I use the FieldTrip logo on my poster?

• Why are so many of the interesting functions in the private directories?
• What other Matlab and non-Matlab toolboxes do I need for FieldTrip?
• Matlab does not see the functions in the "private" directory
• Matlab version 7.3 (2006b) crashes when I try to do ...
• Matlab complains about a missing or invalid MEX file, what should I do?
• How can I compile the mex files on 64 bit Windows?
• How many lines of code does Fieldtrip consist of?
• Should I add FieldTrip with all subdirectories to my Matlab path?
• What is the relation between "events" (such as triggers) and "trials"?
• I am having problems printing figures that use opacity
• How to select the correct SPM toolbox?

• How many people are subscribed to the email discussion list?
• How should I send example data to the developers?
• How should I refer to FieldTrip in my publication?
• I am having problems downloading from the ftp server
• Which version of FieldTrip should I download from the ftp server?
• I am working at the F.C. Donders, should I also download FieldTrip?
• Why is FieldTrip developed separately from EEGLAB?

• How fast is the FieldTrip buffer for realtime data streaming?

• Where can I find the dipoli command-line executable?
• Can I restrict the source reconstruction to the grey matter?
• Can I do combined EEG and MEG source reconstruction?
• Is it important to have accurate measurements of electrode locations for EEG source reconstruction?
• What kind of volume conduction models are implemented?
• How is anatomical, functional or statistical "volume data" described?
• Why is there a rim around the brain for which the source reconstruction is not computed?
• How are the different head and MRI coordinate systems defined?
• How are electrodes, magnetometers or gradiometers described?
• What is the conductivity of the brain, CSF, skull and skin tissue?
• How can I use OpenMEEG for forward modelling?

• How can I reposition the subject for a second MEG session?
• How can I test the serial port connection between two computers?
• How can I use my MacBook Pro for stimulus presentation in the MEG lab?

• Why are the peers using multicast to announce themselves?
• What happens if a job fails to execute properly?
• What happens with a job that has an error on the slave?
• How should I call peercellfun when a function requires many inputs (e.g. key-value pairs)?
• How can I stop the different threads created by peermaster and peerslave?
• Does a firewall affect the communication between peers?

• I would like an automatic daily updated version of the code, can I get access to the CVS or SNV server?
• How can I keep track of the changes to the code?
• How are the various data structures defined?
• What does a typical call to a FieldTrip function look like?
• How can I resolve a svnsync lock?