Multi-taper spectrum - point process times
Usage:
[S,f,R,Serr]=mtspectrumpt(data,params,fscorr,t)
Input:
data (structure array of spike times with dimension channels/trials;
also accepts 1d array of spike times) -- required
params: structure with fields tapers, pad, Fs, fpass, err, trialave
- optional
tapers : precalculated tapers from dpss or in the one of the following
forms:
(1) A numeric vector [TW K] where TW is the
time-bandwidth product and K is the number of
tapers to be used (less than or equal to
2TW-1).
(2) A numeric vector [W T p] where W is the
bandwidth, T is the duration of the data and p
is an integer such that 2TW-p tapers are used. In
this form there is no default i.e. to specify
the bandwidth, you have to specify T and p as
well. Note that the units of W and T have to be
consistent: if W is in Hz, T must be in seconds
and vice versa. Note that these units must also
be consistent with the units of params.Fs: W can
be in Hz if and only if params.Fs is in Hz.
The default is to use form 1 with TW=3 and K=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
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 channels/trials when 1, don't average when 0) - optional. Default 0
fscorr (finite size corrections, 0 (don't use finite size corrections) or
1 (use finite size corrections) - optional
(available only for spikes). Defaults 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:
S (spectrum with dimensions frequency x channels/trials if trialave=0;
dimension frequency if trialave=1)
f (frequencies)
R (rate)
Serr (error bars) - only if err(1)>=10001 function [S,f,R,Serr]=mtspectrumpt(data,params,fscorr,t) 0002 % Multi-taper spectrum - point process times 0003 % 0004 % Usage: 0005 % 0006 % [S,f,R,Serr]=mtspectrumpt(data,params,fscorr,t) 0007 % Input: 0008 % data (structure array of spike times with dimension channels/trials; 0009 % also accepts 1d array of spike times) -- required 0010 % params: structure with fields tapers, pad, Fs, fpass, err, trialave 0011 % - optional 0012 % tapers : precalculated tapers from dpss or in the one of the following 0013 % forms: 0014 % (1) A numeric vector [TW K] where TW is the 0015 % time-bandwidth product and K is the number of 0016 % tapers to be used (less than or equal to 0017 % 2TW-1). 0018 % (2) A numeric vector [W T p] where W is the 0019 % bandwidth, T is the duration of the data and p 0020 % is an integer such that 2TW-p tapers are used. In 0021 % this form there is no default i.e. to specify 0022 % the bandwidth, you have to specify T and p as 0023 % well. Note that the units of W and T have to be 0024 % consistent: if W is in Hz, T must be in seconds 0025 % and vice versa. Note that these units must also 0026 % be consistent with the units of params.Fs: W can 0027 % be in Hz if and only if params.Fs is in Hz. 0028 % The default is to use form 1 with TW=3 and K=5 0029 % 0030 % pad (padding factor for the FFT) - optional (can take values -1,0,1,2...). 0031 % -1 corresponds to no padding, 0 corresponds to padding 0032 % to the next highest power of 2 etc. 0033 % e.g. For N = 500, if PAD = -1, we do not pad; if PAD = 0, we pad the FFT 0034 % to 512 points, if pad=1, we pad to 1024 points etc. 0035 % Defaults to 0. 0036 % Fs (sampling frequency) - optional. Default 1. 0037 % fpass (frequency band to be used in the calculation in the form 0038 % [fmin fmax])- optional. 0039 % Default all frequencies between 0 and Fs/2 0040 % err (error calculation [1 p] - Theoretical error bars; [2 p] - Jackknife error bars 0041 % [0 p] or 0 - no error bars) - optional. Default 0. 0042 % trialave (average over channels/trials when 1, don't average when 0) - optional. Default 0 0043 % fscorr (finite size corrections, 0 (don't use finite size corrections) or 0044 % 1 (use finite size corrections) - optional 0045 % (available only for spikes). Defaults 0. 0046 % t (time grid over which the tapers are to be calculated: 0047 % this argument is useful when calling the spectrum 0048 % calculation routine from a moving window spectrogram 0049 % calculation routine). If left empty, the spike times 0050 % are used to define the grid. 0051 % Output: 0052 % S (spectrum with dimensions frequency x channels/trials if trialave=0; 0053 % dimension frequency if trialave=1) 0054 % f (frequencies) 0055 % R (rate) 0056 % Serr (error bars) - only if err(1)>=1 0057 if nargin < 1; error('Need data'); end; 0058 if nargin < 2; params=[]; end; 0059 [tapers,pad,Fs,fpass,err,trialave,params]=getparams(params); 0060 clear params 0061 data=change_row_to_column(data); 0062 if nargout > 3 && err(1)==0; error('cannot compute error bars with err(1)=0; change params and run again'); end; 0063 if nargin < 3 || isempty(fscorr); fscorr=0;end; 0064 if nargin < 4 || isempty(t); 0065 [mintime,maxtime]=minmaxsptimes(data); 0066 dt=1/Fs; % sampling time 0067 t=mintime-dt:dt:maxtime+dt; % time grid for prolates 0068 end; 0069 N=length(t); % number of points in grid for dpss 0070 nfft=max(2^(nextpow2(N)+pad),N); % number of points in fft of prolates 0071 [f,findx]=getfgrid(Fs,nfft,fpass); % get frequency grid for evaluation 0072 tapers=dpsschk(tapers,N,Fs); % check tapers 0073 [J,Msp,Nsp]=mtfftpt(data,tapers,nfft,t,f,findx); % mt fft for point process times 0074 S=squeeze(mean(conj(J).*J,2)); 0075 if trialave; S=squeeze(mean(S,2));Msp=mean(Msp);end; 0076 R=Msp*Fs; 0077 if nargout==4; 0078 if fscorr==1; 0079 Serr=specerr(S,J,err,trialave,Nsp); 0080 else 0081 Serr=specerr(S,J,err,trialave); 0082 end; 0083 end;