Home > chronux_code > exploratory > correlations > continuous > mtspectrumsegc.m

mtspectrumsegc

PURPOSE ^

Multi-taper segmented spectrum for a single time series - continuous process

SYNOPSIS ^

function [S,f,varS,Serr]=mtspectrumsegc(data,win,tapers,pad,Fs,fpass,segave)

DESCRIPTION ^

 Multi-taper segmented spectrum for a single time series - continuous process

 Usage:

 [S,f,varS]=mtspectrumsegc(data,win,tapers,pad,Fs,fpass,segave)
 Input: 
 Note units have to be consistent. See chronux.m for more information.
       data (column vector) -- required
       win  (duration of the segments) - required. 
       tapers (precalculated tapers from dpss, or in the form [NW K] e.g [3 5]) -- optional. If not 
                                                 specified, use [NW K]=[3 5]
        pad            (padding factor for the FFT) - optional. Defaults to 0.  
                       e.g. For N = 500, if PAD = 0, we pad the FFT 
                       to 512 points; if PAD = 2, we pad the FFT
                       to 2048 points, etc.
       Fs   (sampling frequency) - optional. Default 1.
       fpass    (frequency band to be used in the calculation in the form
                                   [fmin fmax])- optional. 
                                   Default all frequencies between 0 and Fs/2
       segave (1 for averaging across segments, 0 otherwise; default 1)
 Output:
       S       (spectrum in form frequency x channels/trials)
       f       (frequencies)
       varS    (variance of the log spectrum)

CROSS-REFERENCE INFORMATION ^

This function calls: This function is called by:

SOURCE CODE ^

0001 function [S,f,varS,Serr]=mtspectrumsegc(data,win,tapers,pad,Fs,fpass,segave)
0002 % Multi-taper segmented spectrum for a single time series - continuous process
0003 %
0004 % Usage:
0005 %
0006 % [S,f,varS]=mtspectrumsegc(data,win,tapers,pad,Fs,fpass,segave)
0007 % Input:
0008 % Note units have to be consistent. See chronux.m for more information.
0009 %       data (column vector) -- required
0010 %       win  (duration of the segments) - required.
0011 %       tapers (precalculated tapers from dpss, or in the form [NW K] e.g [3 5]) -- optional. If not
0012 %                                                 specified, use [NW K]=[3 5]
0013 %        pad            (padding factor for the FFT) - optional. Defaults to 0.
0014 %                       e.g. For N = 500, if PAD = 0, we pad the FFT
0015 %                       to 512 points; if PAD = 2, we pad the FFT
0016 %                       to 2048 points, etc.
0017 %       Fs   (sampling frequency) - optional. Default 1.
0018 %       fpass    (frequency band to be used in the calculation in the form
0019 %                                   [fmin fmax])- optional.
0020 %                                   Default all frequencies between 0 and Fs/2
0021 %       segave (1 for averaging across segments, 0 otherwise; default 1)
0022 % Output:
0023 %       S       (spectrum in form frequency x channels/trials)
0024 %       f       (frequencies)
0025 %       varS    (variance of the log spectrum)
0026 
0027 if nargin < 2; error('Need data and segment information'); end;
0028 if nargin < 3; tapers=[3 5]; end;
0029 if nargin < 4;pad=0;end;
0030 if nargin < 5; Fs=1; end;
0031 if nargin < 6; fpass=[0 Fs/2]; end;
0032 if nargin < 7; segave=1; end;
0033 if isempty(tapers); tapers=[3 5]; end;
0034 if isempty(pad);pad=0;end;
0035 if isempty(Fs); Fs=1; end;
0036 if isempty(fpass); fpass=[0 Fs/2]; end;
0037 if isempty(segave); segave=1; end;
0038 
0039 N=size(data,1); % total length of data
0040 dt=1/Fs; % sampling interval
0041 T=N*dt; % length of data in seconds
0042 E=[dt:win:T]; % fictitious event triggers
0043 win=[0 win]; % use window length to define left and right limits of windows around triggers
0044 data=createdatamatc(data,E,Fs,win); % segmented data
0045 [S,f]=mtspectrumc(data,tapers,pad,Fs,fpass); % spectra of segmented data
0046 lS=log(S); % log spectrum
0047 varS=var(lS')'; % variance of the log spectrum as a function of frequency
0048 if segave; S=squeeze(mean(S,2)); end;% mean of the spectrum averaged across segments

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