NHP-pRF/Toolboxes/chronux/spectral_analysis/continuous/spsvd.m

function [sv,sp,fm] = spsvd(data,params,mdkp)
% Space frequency SVD of input data - continuous processes
% Usage: [sv,sp,fm] = spsvd(data,params,mdkp)
% Inputs:
% data       (data matrix in timexchannels form)-required
%       params      structure containing parameters - params has the
%       following fields: tapers, Fs, fpass, pad
%           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
%
%	        Fs 	        (sampling frequency) -- optional. Defaults to 1.
%           fpass       (frequency band to be used in the calculation in the form
%                                   [fmin fmax])- optional. 
%                                   Default all frequencies between 0 and Fs/2
%	        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.
% mdkp       (number of dimensions to be kept)-optional. Default is the
%               maximum possible modes determined by taper parameters
%
% Outputs:
% sv sp fm  : singular values, space modes, frequency modes


if nargin < 1; error('Need data'); end;
if nargin < 2 || isempty(params); params=[]; end;
[tapers,pad,Fs,fpass,err,trialave,params]=getparams(params);
clear err trialave params
[N,NCHAN]=size(data);
tapers=dpsschk(tapers,N,Fs);
nfft=max(2^(nextpow2(N)+pad),N);% number of points in fft
[N,K]=size(tapers);
if nargin<3 || isempty(mdkp); mdkp=min(K,NCHAN);
elseif mdkp > min(K,NCHAN); error('mdkp has to be less than both K and NCHAN');end;

tvec=1/Fs *(1:N)';
tvec=repmat(tvec,[1 K]);
tvec=tvec*2*pi*i;
f=getfgrid(Fs,nfft,fpass);
nf=length(f);
sp=zeros(NCHAN,nf,mdkp);
sp=sp+i*sp;
fm=zeros(K,nf,mdkp);
fm=fm+i*fm;
sv=zeros(nf,min([K,NCHAN]));
for j=1:nf 
%     for k=1:K
%       proj(:,k)=tapers(:,k).*exp(-f0*tvec');
%     end
    proj=tapers.*exp(-f(j)*tvec);
    tmp=data'*proj; % projected data
    [u,s,v]= svd(tmp,0); % svd 
    for mk=1:mdkp, 
      sp(:,j,mk)=u(:,mk)';
      fm(:,j,mk)=v(:,mk)';
    end  
    sv(j,:)=diag(s);
end;