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mtdspectrumc

PURPOSE ^

Multi-taper frequency derivative of the spectrum - continuous process

SYNOPSIS ^

function [dS,f]=mtdspectrumc(data,phi,params)

DESCRIPTION ^

 Multi-taper frequency derivative of the spectrum - continuous process

 Usage:

 [dS,f]=mtdspectrumc(data,phi,params)
 Input: 
   Note that all times can be in arbitrary units. But the units have to be
   consistent. So, if E is in secs, win, t have to be in secs, and Fs has to
   be Hz. If E is in samples, so are win and t, and Fs=1. In case of spike
   times, the units have to be consistent with the units of data as well.
       data        (in form samples x channels/trials or a single vector) -- required
       phi         (angle for evaluation of derivative) -- required.
                       e.g. phi=[0,pi/2] gives the time and frequency derivatives
       params: structure with fields tapers, pad, Fs, fpass, 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 (can take values -1,0,1,2...). 
                    -1 corresponds to no padding, 0 corresponds to padding
                    to the next highest power of 2 etc.
                       e.g. For N = 500, if PAD = -1, we do not pad; if PAD = 0, we pad the FFT
                       to 512 points, if pad=1, we pad to 1024 points etc.
                       Defaults to 0.
           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
           trialave (average over trials/channels when 1, don't average when 0) - optional. Default 0
 Output:
       dS       (spectral derivative in form phi x frequency x channels/trials if trialave=0 or in form phi x frequency if trialave=1)
       f        (frequencies)

CROSS-REFERENCE INFORMATION ^

This function calls: This function is called by:

SOURCE CODE ^

0001 function [dS,f]=mtdspectrumc(data,phi,params)
0002 % Multi-taper frequency derivative of the spectrum - continuous process
0003 %
0004 % Usage:
0005 %
0006 % [dS,f]=mtdspectrumc(data,phi,params)
0007 % Input:
0008 %   Note that all times can be in arbitrary units. But the units have to be
0009 %   consistent. So, if E is in secs, win, t have to be in secs, and Fs has to
0010 %   be Hz. If E is in samples, so are win and t, and Fs=1. In case of spike
0011 %   times, the units have to be consistent with the units of data as well.
0012 %       data        (in form samples x channels/trials or a single vector) -- required
0013 %       phi         (angle for evaluation of derivative) -- required.
0014 %                       e.g. phi=[0,pi/2] gives the time and frequency derivatives
0015 %       params: structure with fields tapers, pad, Fs, fpass, 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 (can take values -1,0,1,2...).
0020 %                    -1 corresponds to no padding, 0 corresponds to padding
0021 %                    to the next highest power of 2 etc.
0022 %                       e.g. For N = 500, if PAD = -1, we do not pad; if PAD = 0, we pad the FFT
0023 %                       to 512 points, if pad=1, we pad to 1024 points etc.
0024 %                       Defaults to 0.
0025 %           Fs   (sampling frequency) - optional. Default 1.
0026 %           fpass    (frequency band to be used in the calculation in the form
0027 %                                   [fmin fmax])- optional.
0028 %                                   Default all frequencies between 0 and Fs/2
0029 %           trialave (average over trials/channels when 1, don't average when 0) - optional. Default 0
0030 % Output:
0031 %       dS       (spectral derivative in form phi x frequency x channels/trials if trialave=0 or in form phi x frequency if trialave=1)
0032 %       f        (frequencies)
0033 
0034 if nargin < 2; error('Need data and angle'); end;
0035 if nargin < 3; params=[]; end;
0036 [tapers,pad,Fs,fpass,err,trialave,params]=getparams(params);
0037 clear err params
0038 data=change_row_to_column(data);
0039 N=size(data,1);
0040 nfft=max(2^(nextpow2(N)+pad),N);
0041 [f,findx]=getfgrid(Fs,nfft,fpass); 
0042 tapers=dpsschk(tapers,N,Fs); % check tapers
0043 K=size(tapers,2);
0044 J=mtfftc(data,tapers,nfft,Fs);
0045 J=J(findx,:,:);
0046 A=sqrt(1:K-1);
0047 A=repmat(A,[size(J,1) 1]);
0048 A=repmat(A,[1 1 size(J,3)]);
0049 S=squeeze(mean(J(:,1:K-1,:).*A.*conj(J(:,2:K,:)),2));
0050 if trialave; S=squeeze(mean(S,2));end;
0051 nphi=length(phi);
0052 for p=1:nphi;
0053     dS(p,:,:)=real(exp(i*phi(p))*S);
0054 end;
0055 dS=squeeze(dS);
0056 dS=change_row_to_column(dS);

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