Home > chronux_1_50 > pointtimes > mtspectrumpt.m

mtspectrumpt

PURPOSE ^

Multi-taper spectrum - point process times

SYNOPSIS ^

function [S,f,R,Serr]=mtspectrumpt(data,params,fscorr,t)

DESCRIPTION ^

 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 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
           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)>=1

CROSS-REFERENCE INFORMATION ^

This function calls: This function is called by:

SOURCE CODE ^

0001 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; also accepts 1d array of spike times) -- required
0009 %       params: structure with fields tapers, pad, Fs, fpass, err, trialave
0010 %       - optional
0011 %           tapers (precalculated tapers from dpss, or in the form [NW K] e.g [3 5]) -- optional. If not
0012 %                                                 specified, use [NW K]=[3 5]
0013 %            pad            (padding factor for the FFT) - optional (can take values -1,0,1,2...).
0014 %                    -1 corresponds to no padding, 0 corresponds to padding
0015 %                    to the next highest power of 2 etc.
0016 %                       e.g. For N = 500, if PAD = -1, we do not pad; if PAD = 0, we pad the FFT
0017 %                       to 512 points, if pad=1, we pad to 1024 points etc.
0018 %                       Defaults to 0.
0019 %           Fs   (sampling frequency) - optional. Default 1.
0020 %           fpass    (frequency band to be used in the calculation in the form
0021 %                                   [fmin fmax])- optional.
0022 %                                   Default all frequencies between 0 and Fs/2
0023 %           err  (error calculation [1 p] - Theoretical error bars; [2 p] - Jackknife error bars
0024 %                                   [0 p] or 0 - no error bars) - optional. Default 0.
0025 %           trialave (average over channels/trials when 1, don't average when 0) - optional. Default 0
0026 %       fscorr   (finite size corrections, 0 (don't use finite size corrections) or 1 (use finite size corrections) - optional
0027 %                (available only for spikes). Defaults 0.
0028 %       t        (time grid over which the tapers are to be calculated:
0029 %                      this argument is useful when calling the spectrum
0030 %                      calculation routine from a moving window spectrogram
0031 %                      calculation routine). If left empty, the spike times
0032 %                      are used to define the grid.
0033 % Output:
0034 %       S       (spectrum with dimensions frequency x channels/trials if trialave=0; dimension frequency if trialave=1)
0035 %       f       (frequencies)
0036 %       R       (rate)
0037 %       Serr    (error bars) - only if err(1)>=1
0038 if nargin < 1; error('Need data'); end;
0039 if nargin < 2; params=[]; end;
0040 [tapers,pad,Fs,fpass,err,trialave,params]=getparams(params);
0041 clear params
0042 data=change_row_to_column(data);
0043 if nargout > 3 && err(1)==0; error('cannot compute error bars with err(1)=0; change params and run again'); end;
0044 if nargin < 3 || isempty(fscorr); fscorr=0;end;
0045 if nargin < 4 || isempty(t);
0046    [mintime,maxtime]=minmaxsptimes(data);
0047    dt=1/Fs; % sampling time
0048    t=mintime-dt:dt:maxtime+dt; % time grid for prolates
0049 end;
0050 N=length(t); % number of points in grid for dpss
0051 nfft=max(2^(nextpow2(N)+pad),N); % number of points in fft of prolates
0052 [f,findx]=getfgrid(Fs,nfft,fpass); % get frequency grid for evaluation
0053 tapers=dpsschk(tapers,N,Fs); % check tapers
0054 [J,Msp,Nsp]=mtfftpt(data,tapers,nfft,t,f,findx); % mt fft for point process times
0055 S=squeeze(mean(conj(J).*J,2));
0056 if trialave; S=squeeze(mean(S,2));Msp=mean(Msp);end;
0057 R=Msp*Fs;
0058 if nargout==4;
0059    if fscorr==1;
0060       Serr=specerr(S,J,err,trialave,Nsp);
0061    else
0062       Serr=specerr(S,J,err,trialave);
0063    end;
0064 end;

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