function [dS,t,f]=mtdspecgrampt(data,movingwin,phi,params)
% Multi-taper derivative time-frequency spectrum - point process times
%
% Usage:
%
% [dS,t,f]=mtdspecgrampt(data,movingwin,phi,params)
% Input: 
%   Note that all times can be in arbitrary units. But the units have to be
%   consistent. So, if E is in secs, win, t have to be in secs, and Fs has to
%   be Hz. If E is in samples, so are win and t, and Fs=1. In case of spike
%   times, the units have to be consistent with the units of data as well.
%       data        (structure array of spike times with dimension channels/trials; 
%                   also accepts 1d array of spike times) -- required
%       movingwin         (in the form [window winstep] i.e length of moving
%                                                 window and step size.
%                                                 Note that units here have
%                                                 to be consistent with
%                                                 units of Fs
%       phi         (angle for evaluation of derivative) -- required.
%                       e.g. phi=[0,pi/2] giving the time and frequency
%                       derivatives
%       params: structure with fields tapers, pad, Fs, fpass, 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
%                   Note that T has to be equal to movingwin(1).
%
%	        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
%           trialave (average over trials when 1, don't average when 0) -
%           optional. Default 0
% Output:
%       dS      (spectral derivative in form phi x time x frequency x channels/trials if trialave=0; 
%               in form phi x time x frequency if trialave=1)
%       t       (times)
%       f       (frequencies)

if nargin < 3; error('Need data, window parameters and angle'); end;
if nargin < 4; params=[]; end;

if length(params.tapers)==3 & movingwin(1)~=params.tapers(2);
    error('Duration of data in params.tapers is inconsistent with movingwin(1), modify params.tapers(2) to proceed')
end

[tapers,pad,Fs,fpass,err,trialave,params]=getparams(params);
clear err 
[mintime,maxtime]=minmaxsptimes(data);
tn=(mintime+movingwin(1)/2:movingwin(2):maxtime-movingwin(1)/2);
Nwin=round(Fs*movingwin(1)); % number of samples in window
% Nstep=round(movingwin(2)*Fs); % number of samples to step through
nfft=max(2^(nextpow2(Nwin)+pad),Nwin);
f=getfgrid(Fs,nfft,fpass); Nf=length(f);
params.tapers=dpsschk(tapers,Nwin,Fs); % check tapers
%K=size(params.tapers,2);
nw=length(tn);
if trialave==0; dS=zeros(length(phi),nw,Nf,C); else dS=zeros(length(phi),nw,Nf); end;
for n=1:nw;
   t=linspace(tn(n)-movingwin(1)/2,tn(n)+movingwin(1)/2,Nwin);
   datawin=extractdatapt(data,[t(1) t(end)]);
   [ds,f]=mtdspectrumpt(datawin,phi,params,t);
   dS(:,n,:,:)=ds;
end;
sz=size(ds);
dS=squeeze(dS);
% if length(sz)==3;
%    dS=permute(dS,[2 1 3 4]);
% elseif length(phi)>1
%    dS=permute(dS,[2 1 3]);
% end;
t=tn;