NHP-pRF/Toolboxes/chronux/spectral_analysis/pointtimes/CrossSpecMatpt.m

function [Sc,Cmat,Ctot,Cvec,Cent,f]=CrossSpecMatpt(data,win,T,params)
%
%
% Multi-taper cross-spectral matrix - another routine, this one allows for multiple trials and channels 
% but does not do confidence intervals. Also this routine always averages
% over trials - point process as times
%
% Usage:
%
% [Sc,Cmat,Ctot,Cvec,Cent,f]=CrossSpecMatpt(data,win,T,params)
% Input: 
% Note units have to be consistent. See chronux.m for more information.
%       data (as a struct array with dimensions channels x trials) - note
%       that times of measurement have to be consistent, we assume all
%       times are specified relative to the start time of the trials which
%       are taken to be zero.
%       win  (duration of non-overlapping window)
%       trialduration (since it is not possible to infer trial duration
%               from spike times, this is an optional argument. If not specified
%               the routine uses the minimum and maximum spike time (across all
%               channels and trials) as the window of calculation.) -
%               optional
%       params: structure with fields tapers, pad, Fs, fpass
%       - 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
% Output:
%       Sc (cross spectral matrix frequency x channels x channels)
%       Cmat Coherence matrix frequency x channels x channels
%       Ctot Total coherence: SV(1)^2/sum(SV^2) (frequency)
%       Cvec leading Eigenvector (frequency x channels)
%       Cent A different measure of total coherence: GM/AM of SV^2s
%       f (frequencies)  
d=ndims(data);
if size(d,1)==1; error('Need multiple channels; are you sure your format is channels x trials ?');end;
[C,Ntr]=size(data);
mintime=0;
if nargin < 3; [mintime,maxtime]=minmaxsptimes(data);clear mintime;
else maxtime=T; end;
if nargin < 4; params=[]; end;
[tapers,pad,Fs,fpass,err,trialave,params]=getparams(params);
clear err trialave params
Nwin=round(Fs*win); % number of samples in window
nfft=max(2^(nextpow2(Nwin)+pad),Nwin);
[f,findx]=getfgrid(Fs,nfft,fpass); 
tapers=dpsschk(tapers,Nwin,Fs); % check tapers
twin=linspace(0,win,Nwin); % times of occurrence of "samples" within window - times of evaluation of tapers

Sc=zeros(length(findx),C,C);
tn=mintime:win:maxtime-win;
Nwins=length(tn);
if d==3, % If there are multiple trials
for iwin=1:Nwins,
    t=[tn(iwin) tn(iwin)+T];
    for i=1:Ntr, 
        data1=data(:,i);
        data1=extractdatapt(data1,t,1); % extract spike times in window,reset times to be relative to beginning of window
        J1=mtfftpt(data1,tapers,nfft,twin,f,findx);
        for k=1:C,
            for l=1:C,
                spec=squeeze(mean(conj(J1(:,:,k)).*J1(:,:,l),2)); 
            Sc(:,k,l)=Sc(:,k,l)+spec;
            end
        end
    end
end
Sc=Sc/(Nwins*Ntr);
end

if d==2, % only one trial
for iwin=1:Nwins,
        data1=data(:,i);
        data1=extractdatapt(data1,t,1); % extract spike times in window,reset times to be relative to beginning of window
        J1=mtfftpt(data1,tapers,nfft,twin,f,findx);
        for k=1:C,
            for l=1:C,
            Sc(:,k,l)=Sc(:,k,l)+squeeze(mean(conj(J1(:,:,k)).*J1(:,:,l),2));
            end
        end
end
Sc=Sc/Nwins;
end

Cmat=Sc;
Sdiag=zeros(length(findx),C);
for k=1:C,
    Sdiag(:,k)=squeeze(Sc(:,k,k));
end

for k=1:C,
    for l=1:C,
        Cmat(:,k,l)=Sc(:,k,l)./sqrt(abs(Sdiag(:,k).*Sdiag(:,l)));
    end
end

Ctot=zeros(length(findx),1); Cent=Ctot;
Cvec=zeros(length(findx),C);
for i=1:length(findx),
    [u s]=svd(squeeze(Sc(i,:,:)));s=diag(s);
%     Ctot(i)=s(1)/sum(s); Cent(i)=exp(mean(log(s.^2)))/mean(s.^2);             
    Ctot(i)=s(1)/sum(s); Cent(i)=exp(mean(log(s)))/mean(s);             
    Cvec(i,:)=transpose(u(:,1));

end