


Multi-taper spectral derivative - point process times
Usage:
[dS,f]=mtdspectrumpt(data,phi,params,t)
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 (structure array of spike times with dimension channels/trials; also accepts 1d array of spike times) -- required
phi (angle for evaluation of derivative) -- required.
e.g. phi=[0,pi/2] giving 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 when 1, don't average when 0) -
optional. Default 0
t (time grid over which the tapers are to be calculated:
this argument is useful when calling the spectrum
calculation routine from a moving window spectrogram
calculation routine). If left empty, the spike times
are used to define the grid.
Output:
dS (spectral derivative in form phi x frequency x channels/trials if trialave=0; function of phi x frequency if trialave=1)
f (frequencies)

0001 function [dS,f]=mtdspectrumpt(data,phi,params,t) 0002 % Multi-taper spectral derivative - point process times 0003 % 0004 % Usage: 0005 % 0006 % [dS,f]=mtdspectrumpt(data,phi,params,t) 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 (structure array of spike times with dimension channels/trials; also accepts 1d array of spike times) -- required 0013 % phi (angle for evaluation of derivative) -- required. 0014 % e.g. phi=[0,pi/2] giving 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 when 1, don't average when 0) - 0028 % optional. Default 0 0029 % t (time grid over which the tapers are to be calculated: 0030 % this argument is useful when calling the spectrum 0031 % calculation routine from a moving window spectrogram 0032 % calculation routine). If left empty, the spike times 0033 % are used to define the grid. 0034 % Output: 0035 % dS (spectral derivative in form phi x frequency x channels/trials if trialave=0; function of phi x frequency if trialave=1) 0036 % f (frequencies) 0037 if nargin < 2; error('Need data and angle'); end; 0038 if nargin < 3; params=[]; end; 0039 [tapers,pad,Fs,fpass,err,trialave,params]=getparams(params); 0040 clear err params 0041 data=change_row_to_column(data); 0042 dt=1/Fs; % sampling time 0043 if nargin < 4; 0044 [mintime,maxtime]=minmaxsptimes(data); 0045 t=mintime:dt:maxtime+dt; % time grid for prolates 0046 end; 0047 N=length(t); % number of points in grid for dpss 0048 nfft=2^(nextpow2(N)+pad); % number of points in fft of prolates 0049 [f,findx]=getfgrid(Fs,nfft,fpass); % get frequency grid for evaluation 0050 tapers=dpsschk(tapers,N,Fs); % check tapers 0051 K=size(tapers,2); 0052 J=mtfftpt(data,tapers,nfft,Fs,t,f,findx); % mt fft for point process times 0053 A=sqrt(1:K-1); 0054 A=repmat(A,[size(J,1) 1]); 0055 A=repmat(A,[1 1 size(J,3)]); 0056 S=squeeze(mean(J(:,1:K-1,:).*A.*conj(J(:,2:K,:)),2)); 0057 if trialave; S=squeeze(mean(S,2));end; 0058 nphi=length(phi); 0059 for p=1:nphi; 0060 dS(p,:,:)=real(exp(i*phi(p))*S); 0061 end; 0062 dS=squeeze(dS); 0063 dS=change_row_to_column(dS);