function [tfr,t,f] = tfrppage(x,t,N,h,trace);%TFRPPAGE Pseudo Page time-frequency distribution.%	[TFR,T,F]=TFRPPAGE(X,T,N,H,TRACE) computes the Pseudo Page %	distribution of a discrete-time signal X, or the%	cross Pseudo Page representation between two signals. % %	X     : signal if auto-PPage, or [X1,X2] if cross-PPage.%	T     : time instant(s)          (default : 1:length(X)).%	N     : number of frequency bins (default : length(X)).%	H     : frequency smoothing window, H(0) being forced to 1.%	                                 (default : Hamming(N/4)). %	TRACE : if nonzero, the progression of the algorithm is shown%	                                 (default : 0).%	TFR   : time-frequency representation. When called without %	        output arguments, TFRPPAGE runs TFRQVIEW.%	F     : vector of normalized frequencies.%%	Example :%	 sig=fmlin(128,0.1,0.4); tfrppage(sig);% %	See also all the time-frequency representations listed in%	 the file CONTENTS (TFR*)%	F. Auger, May-August 1994, July 1995.%	Copyright (c) 1996 by CNRS (France).%%	------------------- CONFIDENTIAL PROGRAM -------------------- %	This program can not be used without the authorization of its%	author(s). For any comment or bug report, please send e-mail to %	f.auger@ieee.org[xrow,xcol] = size(x);if (nargin < 1), error('At least 1 parameter is required');elseif nargin<=2, N=xrow;end;hlength=floor(N/4);if (rem(hlength,2)==0), hlength=hlength+1;end;if (nargin == 1), t=1:xrow; h = window(hlength); trace=0;elseif (nargin == 2 | nargin == 3), h = window(hlength); trace = 0;elseif (nargin == 4), trace = 0;end;if (N<0), error('N must be greater than zero');end;[trow,tcol] = size(t);if (xcol==0)|(xcol>2), error('X must have one or two columns');elseif (trow~=1), error('T must only have one row'); elseif (2^nextpow2(N)~=N), fprintf('For a faster computation, N should be a power of two\n');end; [hrow,hcol]=size(h); Lh=(hrow-1)/2; h=h/h(Lh+1);if (hcol~=1)|(rem(hrow,2)==0), error('H must be a smoothing window with odd length');end;tfr= zeros (N,tcol) ;  if trace, disp('Pseudo Page distribution'); end;for icol=1:tcol, ti= t(icol); tau=0:min([N-1,Lh,ti-1]); indices= rem(N+tau,N)+1; if trace, disprog(icol,tcol,10); end; tfr(indices,icol)=h(Lh+1+tau).*x(ti,1).*conj(x(ti-tau,xcol));end; if trace, fprintf('\n'); end;tfr= real(fft(tfr)); if (nargout==0), tfrqview(tfr,x,t,'tfrppage',h);elseif (nargout==3), if rem(N,2)==0, 
  f=[0:N/2-1 -N/2:-1]'/N;
 else
  f=[0:(N-1)/2 -(N-1)/2:-1]'/N;  
 end;
end;