Home > chronux > spectral_analysis > pointbinned > mtspectrumsegpb.m

# mtspectrumsegpb

## PURPOSE Multi-taper segmented spectrum for a univariate binned point process

## SYNOPSIS function [S,f,R,varS,zerosp,C,Serr]=mtspectrumsegpb(data,win,params,segave,fscorr)

## DESCRIPTION ``` Multi-taper segmented spectrum for a univariate binned point process

Usage:

[S,f,R,varS,zerosp,C,Serr]=mtspectrumsegpb(data,win,params,segave,fscorr)
Input:
data (single vector) -- required
win  (duration of the segments) - required.
params: structure with fields tapers, pad, Fs, fpass, err
- 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...).
to the next highest power of 2 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.
segave (1 for averaging across segments, 0 otherwise; default 1)
fscorr   (finite size corrections, 0 (don't use finite size corrections) or
1 (use finite size corrections) - optional
(available only for spikes). Defaults 0.
Output:
S       (spectrum in form frequency x segments if segave=0; as a function of frequency if segave=1)
f       (frequencies)
R       (spike rate)
varS    (variance of the log spectrum)
zerosp  (0 for segments in which spikes were found, 1 for segments
in which there are no spikes)
C       (covariance matrix of the log spectrum - frequency x
frequency matrix)
Serr    (error bars) - only for err(1)>=1```

## CROSS-REFERENCE INFORMATION This function calls:
This function is called by:

## SOURCE CODE ```0001 function [S,f,R,varS,zerosp,C,Serr]=mtspectrumsegpb(data,win,params,segave,fscorr)
0002 % Multi-taper segmented spectrum for a univariate binned point process
0003 %
0004 % Usage:
0005 %
0006 % [S,f,R,varS,zerosp,C,Serr]=mtspectrumsegpb(data,win,params,segave,fscorr)
0007 % Input:
0008 % Note units have to be consistent. See chronux.m for more information.
0009 %       data (single vector) -- required
0010 %       win  (duration of the segments) - required.
0011 %       params: structure with fields tapers, pad, Fs, fpass, err
0012 %       - optional
0013 %            tapers : precalculated tapers from dpss or in the one of the following
0014 %                     forms:
0015 %                    (1) A numeric vector [TW K] where TW is the
0016 %                        time-bandwidth product and K is the number of
0017 %                        tapers to be used (less than or equal to
0018 %                        2TW-1).
0019 %                    (2) A numeric vector [W T p] where W is the
0020 %                        bandwidth, T is the duration of the data and p
0021 %                        is an integer such that 2TW-p tapers are used. In
0022 %                        this form there is no default i.e. to specify
0023 %                        the bandwidth, you have to specify T and p as
0024 %                        well. Note that the units of W and T have to be
0025 %                        consistent: if W is in Hz, T must be in seconds
0026 %                        and vice versa. Note that these units must also
0027 %                        be consistent with the units of params.Fs: W can
0028 %                        be in Hz if and only if params.Fs is in Hz.
0029 %                        The default is to use form 1 with TW=3 and K=5
0030 %
0031 %            pad            (padding factor for the FFT) - optional (can take values -1,0,1,2...).
0033 %                    to the next highest power of 2 etc.
0034 %                       e.g. For N = 500, if PAD = -1, we do not pad; if PAD = 0, we pad the FFT
0035 %                       to 512 points, if pad=1, we pad to 1024 points etc.
0036 %                       Defaults to 0.
0037 %           Fs   (sampling frequency) - optional. Default 1.
0038 %           fpass    (frequency band to be used in the calculation in the form
0039 %                                   [fmin fmax])- optional.
0040 %                                   Default all frequencies between 0 and Fs/2
0041 %           err  (error calculation [1 p] - Theoretical error bars; [2 p] - Jackknife error bars
0042 %                                   [0 p] or 0 - no error bars) - optional. Default 0.
0043 %       segave (1 for averaging across segments, 0 otherwise; default 1)
0044 %       fscorr   (finite size corrections, 0 (don't use finite size corrections) or
0045 %                1 (use finite size corrections) - optional
0046 %                (available only for spikes). Defaults 0.
0047 % Output:
0048 %       S       (spectrum in form frequency x segments if segave=0; as a function of frequency if segave=1)
0049 %       f       (frequencies)
0050 %       R       (spike rate)
0051 %       varS    (variance of the log spectrum)
0052 %       zerosp  (0 for segments in which spikes were found, 1 for segments
0053 %       in which there are no spikes)
0054 %       C       (covariance matrix of the log spectrum - frequency x
0055 %       frequency matrix)
0056 %       Serr    (error bars) - only for err(1)>=1
0057
0058
0059 if nargin < 2; error('Need data and segment information'); end;
0060 if nargin < 3; params=[]; end;
0061 if nargin < 4 || isempty(segave); segave=1; end;
0063 clear params trialave
0064 if nargin < 3 || isempty(fscorr); fscorr=0;end;
0065
0066 if nargout > 4 && err(1)==0;
0067 %   Cannot compute error bars with err(1)=0. Need to change params and run again.
0068     error('When Serr is desired, err(1) has to be non-zero.');
0069 end;
0070 data=change_row_to_column(data);
0071 N=size(data,1); % total length of data
0072 dt=1/Fs; % sampling interval
0073 T=N*dt; % length of data in seconds
0074 E=0:win:T-win; % fictitious event triggers
0075 win=[0 win]; % use window length to define left and right limits of windows around triggers
0076 data=createdatamatpb(data,E,Fs,win);
0077 N=size(data,1); % length of segmented data
0079 [f,findx]=getfgrid(Fs,nfft,fpass);
0080 tapers=dpsschk(tapers,N,Fs); % check tapers
0081 [J,Msp,Nsp]=mtfftpb(data,tapers,nfft);
0082 J=J(findx,:,:);
0083 R=Msp*Fs;
0084 S=squeeze(mean(conj(J).*J,2)); % spectra of non-overlapping segments (averaged over tapers)
0085 if segave==1; SS=squeeze(mean(S,2));R=mean(R);else;SS=S;end;% mean of the spectrum averaged across segments
0086 if nargout > 3
0087     lS=log(SS); % log spectrum for nonoverlapping segments
0088 %     varS=var(lS,1,2); % variance of log spectrum
0089     varS=var(lS',1)';% variance of the log spectrum R13
0090     if nargout > 4
0091        zerosp=zeros(1,size(data,2));
0092        zerosp(Nsp==0)=1;
0093        if nargout > 5
0094           C=cov(lS'); % covariance matrix of the log spectrum
0095           if nargout==7;
0096              if fscorr==1;
0097                 Serr=specerr(SS,J,err,segave,Nsp);
0098              else
0099                 Serr=specerr(SS,J,err,segave);
0100              end;
0101           end;
0102        end;
0103     end;
0104 end;
0105 S=SS;```

Generated on Fri 28-Sep-2012 12:34:30 by m2html © 2005