


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)

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);