[FieldTrip] specifying the variables for ft_specest_mtmfft

Eelke Spaak eelke.spaak at donders.ru.nl
Wed Feb 19 18:04:27 CET 2014

Dear Hweeling,

ft_specest_mtmfft is one of the lower-level FieldTrip functions, which
the end-user typically should not use. Instead, have a look at the
documentation for ft_freqanalysis (type 'edit ft_freqanalysis' or look
here: http://fieldtrip.fcdonders.nl/reference/ft_freqanalysis). There
is a section specifically relating to options for mtmfft. All the
options for ft_freqanalysis and other FieldTrip functions are
specified using a 'cfg'-structure, e.g. like so:

cfg = [];
cfg.method = 'mtmfft';
cfg.taper = 'hanning';
cfg.foi = 1:150;
freq = ft_freqanalysis(cfg, data);


On 19 February 2014 16:57, Hwee Ling Lee <hweeling.lee at gmail.com> wrote:
> Dear all,
> I'm new to fieldtrip, and I would like to estimate the spectrum using
> ft_specest_mtmfft. With the help function, I understand that there are
> certain variables that I need to input in order for the mtmfft to work.
> I have some questions regarding the input variables.
> I have 4 intracranial channels and I cut my trials into segments of 2048
> datapoints. My sampling resolution is 1000 Hz.
> Variables that I know what the inputs are:
> For dat, I know that this is the raw data for each segment.
> For time, I know that this is the time vector of each segment (in my case,
> it would be 0:0.001:2.048).
> For taper, I will be using 'hanning'.
> For freqoi, I'm interested in the frequency from 1:150.
> Variables that I don't know and not sure what to input:
> For ntaper, I would like to use multiple taper, however, I'm not sure how
> many number of tapers I should use.
> For spectrum, it states that it requires a matrix of taper*chan*freqoi of
> fourier coefficients. I'm not sure what this means at all.
> Could someone please help me with the variables that I'm not sure of?
> Thanks!
> Best regards,
> Hweeling
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