


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. 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
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. 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 % trialave (average over trials/channels when 1, don't average when 0) - optional. Default 0 0028 % Output: 0029 % dS (spectral derivative in form phi x frequency x channels/trials if trialave=0 or in form phi x frequency if trialave=1) 0030 % f (frequencies) 0031 0032 if nargin < 2; error('Need data and angle'); end; 0033 if nargin < 3; params=[]; end; 0034 [tapers,pad,Fs,fpass,err,trialave,params]=getparams(params); 0035 clear err params 0036 data=change_row_to_column(data); 0037 N=size(data,1); 0038 nfft=2^(nextpow2(N)+pad); 0039 [f,findx]=getfgrid(Fs,nfft,fpass); 0040 tapers=dpsschk(tapers,N,Fs); % check tapers 0041 K=size(tapers,2); 0042 J=mtfftc(data,tapers,nfft,Fs); 0043 J=J(findx,:,:); 0044 A=sqrt(1:K-1); 0045 A=repmat(A,[size(J,1) 1]); 0046 A=repmat(A,[1 1 size(J,3)]); 0047 S=squeeze(mean(J(:,1:K-1,:).*A.*conj(J(:,2:K,:)),2)); 0048 if trialave; S=squeeze(mean(S,2));end; 0049 nphi=length(phi); 0050 for p=1:nphi; 0051 dS(p,:,:)=real(exp(i*phi(p))*S); 0052 end; 0053 dS=squeeze(dS); 0054 dS=change_row_to_column(dS);