[FieldTrip] ft_connectivityanalysis time elapsed

[Schoffelen, J.M. (Jan Mathijs)]

Hi Raghavan,

I suggest to use the matlab profiler to try and find out where most time is spent in both function calls. This will give you an indication of the cause of your observation.

Best wishes,
Jan-Mathijs


On 12 Jun 2022, at 20:52, Raghavan Gopalakrishnan via fieldtrip <fieldtrip at science.ru.nl<mailto:fieldtrip at science.ru.nl>> wrote:


 Hi all,
I have a question regarding the ft_connectivityanalysis.
Computing coherence for 33 channels takes only 2.89 seconds(example-1), where computing coherence between 2 channels takes 20 seconds (example-2).
Any idea why this might be the case? Shouldn’t Computing coherence between 2 channels take way less time than all channels?


Example-1:

freq1 =

  struct with fields:

            label: {35×1 cell}
           dimord: 'rpttap_chan_freq_time'
             freq: [1.9989 2.9983 … ]
             time: [-0.5000 -0.4900 … ]
    fourierspctrm: [48×35×44×201 double]
        cumtapcnt: [48×44 double]
        trialinfo: [48×9 double]
              cfg: [1×1 struct]

cfg =

  struct with fields:

        method: 'coh'
    channelcmb: {'eeg'  'DBS234-567'}


tic;
ccc_coh = ft_connectivityanalysis(cfg, freq1);
toc;

Elapsed time is 2.890037 seconds.

ccc_coh =

  struct with fields:

       dimord: 'chan_chan_freq_time'
    cohspctrm: [33×33×44×201 double]
         time: [-0.5000 -0.4900 … ]
         freq: [1.9989 2.9983 3.9978 … ]
          cfg: [1×1 struct]
        label: {33×1 cell}

Example-2

freq1 =

  struct with fields:

            label: {2×1 cell}
           dimord: 'rpttap_chan_freq_time'
             freq: [1.9989 2.9983 … ]
             time: [-0.5000 -0.4900 … ]
    fourierspctrm: [48×2×44×201 double]
        cumtapcnt: [48×44 double]
        trialinfo: [48×9 double]
              cfg: [1×1 struct]

cfg =

  struct with fields:

        method: 'coh'
    channelcmb: {'C4'  'DBS234-567'}

tic;
ccc_coh = ft_connectivityanalysis(cfg, freq1);
toc;

Elapsed time is 20.119044 seconds.
ccc_coh =

  struct with fields:

        label: {2×1 cell}
       dimord: 'chan_chan_freq_time'
    cohspctrm: [2×2×44×201 double]
         time: [-0.5000 -0.4900 … ]
         freq: [1.9989 2.9983 3.9978 … ]
          dof: [48 48 48 48 48 48 48 … ]
          cfg: [1×1 struct]

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