Home > chronux_1_1 > continuous > mtspecgramc.m

mtspecgramc

PURPOSE ^

Multi-taper time-frequency spectrum - continuous process

SYNOPSIS ^

function [S,t,f,Serr]=mtspecgramc(data,movingwin,params)

DESCRIPTION ^

 Multi-taper time-frequency spectrum - continuous process

 Usage:
 [S,t,f,Serr]=mtspecgramc(data,movingwin,params)
 Input: 
 Note units have to be consistent. Thus, if movingwin is in seconds, Fs
 has to be in Hz. see chronux.m for more information.
       data        (in form samples x channels/trials) -- required
       movingwin         (in the form [window winstep] i.e length of moving
                                                 window and step size)
                                                 Note that units here have
                                                 to be consistent with
                                                 units of Fs - required
       params: structure with fields tapers, pad, Fs, fpass, err, trialave
       - optional
           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
           err  (error calculation [1 p] - Theoretical error bars; [2 p] - Jackknife error bars
                                   [0 p] or 0 - no error bars) - optional. Default 0.
           trialave (average over trials/channels when 1, don't average when 0) - optional. Default 0
 Output:
       S       (spectrum in form time x frequency x channels/trials if trialave=0; in the form time x frequency if trialave=1)
       t       (times)
       f       (frequencies)
       Serr    (error bars) only for err(1)>=1

CROSS-REFERENCE INFORMATION ^

This function calls: This function is called by:

SOURCE CODE ^

0001 function [S,t,f,Serr]=mtspecgramc(data,movingwin,params)
0002 % Multi-taper time-frequency spectrum - continuous process
0003 %
0004 % Usage:
0005 % [S,t,f,Serr]=mtspecgramc(data,movingwin,params)
0006 % Input:
0007 % Note units have to be consistent. Thus, if movingwin is in seconds, Fs
0008 % has to be in Hz. see chronux.m for more information.
0009 %       data        (in form samples x channels/trials) -- required
0010 %       movingwin         (in the form [window winstep] i.e length of moving
0011 %                                                 window and step size)
0012 %                                                 Note that units here have
0013 %                                                 to be consistent with
0014 %                                                 units of Fs - required
0015 %       params: structure with fields tapers, pad, Fs, fpass, err, trialave
0016 %       - optional
0017 %           tapers (precalculated tapers from dpss, or in the form [NW K] e.g [3 5]) -- optional. If not
0018 %                                                 specified, use [NW K]=[3 5]
0019 %            pad            (padding factor for the FFT) - optional. Defaults to 0.
0020 %                       e.g. For N = 500, if PAD = 0, we pad the FFT
0021 %                       to 512 points; if PAD = 2, we pad the FFT
0022 %                       to 2048 points, etc.
0023 %           Fs   (sampling frequency) - optional. Default 1.
0024 %           fpass    (frequency band to be used in the calculation in the form
0025 %                                   [fmin fmax])- optional.
0026 %                                   Default all frequencies between 0 and Fs/2
0027 %           err  (error calculation [1 p] - Theoretical error bars; [2 p] - Jackknife error bars
0028 %                                   [0 p] or 0 - no error bars) - optional. Default 0.
0029 %           trialave (average over trials/channels when 1, don't average when 0) - optional. Default 0
0030 % Output:
0031 %       S       (spectrum in form time x frequency x channels/trials if trialave=0; in the form time x frequency if trialave=1)
0032 %       t       (times)
0033 %       f       (frequencies)
0034 %       Serr    (error bars) only for err(1)>=1
0035 
0036 if nargin < 2; error('Need data and window parameters'); end;
0037 if nargin < 3; params=[]; end;
0038 [tapers,pad,Fs,fpass,err,trialave,params]=getparams(params);
0039 if nargout > 3 && err(1)==0; 
0040 %   Cannot compute error bars with err(1)=0. change params and run again.
0041     error('When Serr is desired, err(1) has to be non-zero.');
0042 end;
0043 data=change_row_to_column(data);
0044 [N,Ch]=size(data);
0045 Nwin=round(Fs*movingwin(1)); % number of samples in window
0046 Nstep=round(movingwin(2)*Fs); % number of samples to step through
0047 nfft=2^(nextpow2(Nwin)+pad);
0048 f=getfgrid(Fs,nfft,fpass); Nf=length(f);
0049 params.tapers=dpsschk(tapers,Nwin,Fs); % check tapers
0050 
0051 winstart=1:Nstep:N-Nwin+1;
0052 nw=length(winstart); 
0053 
0054 if trialave
0055     S = zeros(nw,Nf);
0056     if nargout==4; Serr=zeros(2,nw,Nf); end;
0057 else
0058     S = zeros(nw,Nf,Ch);
0059     if nargout==4; Serr=zeros(2,nw,Nf,Ch); end;
0060 end
0061 
0062 for n=1:nw;
0063    indx=winstart(n):winstart(n)+Nwin-1;
0064    datawin=data(indx,:);
0065    if nargout==4
0066      [s,f,serr]=mtspectrumc(datawin,params);
0067      Serr(1,n,:,:)=squeeze(serr(1,:,:));
0068      Serr(2,n,:,:)=squeeze(serr(2,:,:));
0069    else
0070      [s,f]=mtspectrumc(datawin,params);
0071    end
0072    S(n,:,:)=s;
0073 end;
0074 S=squeeze(S); 
0075 if nargout==4;Serr=squeeze(Serr);end;
0076 winmid=winstart+round(Nwin/2);
0077 t=winmid/Fs;

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