function [tfr,t,f] = tfrri(x,t,N,trace);%TFRRI	Rihaczek time-frequency distribution.%	[TFR,T,F]=TFRRI(X,T,N,TRACE) computes the Rihaczek distribution%	of a discrete-time signal X, %	or the cross Rihaczek representation between two signals. % %	X     : signal if auto-Ri, or [X1,X2] if cross-Ri.%	T     : time instant(s)           (default : 1:length(X)).%	N     : number of frequency bins  (default : length(X)).%	TRACE : if nonzero, the progression of the algorithm is shown%	                                  (default : 0).%	TFR   : time-frequency representation. When called without %	       output arguments, TFRRI applies TFRQVIEW on the real%	       part of the distribution, which is equal to the%	       Margenau-Hill distribution.%	F     : vector of normalized frequencies.%%	Example :%	 sig=fmlin(128,0.1,0.4); tfrri(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.orgif (nargin == 0), error('At least 1 parameter required');end;[xrow,xcol] = size(x);if (nargin == 1), t=1:xrow; N=xrow; trace=0;elseif (nargin == 2), N=xrow; trace=0;elseif (nargin == 3), 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 & nargin==4), fprintf('For a faster computation, N should be a power of two\n');end; tfr= zeros (N,tcol) ;  if trace, disp('Rihaczek distribution'); end;for icol=1:tcol, ti= t(icol); tau=-min([N-ti,xrow-ti]):(ti-1); indices= rem(N+tau,N)+1;  if trace, disprog(icol,tcol,10); end; tfr(indices,icol)=x(ti,1)*conj(x(ti-tau,xcol));end; if trace, fprintf('\n'); end;tfr= fft(tfr); if (nargout==0), fprintf('if your goal is a graphical output, you should rather use tfrmh.\n'); tfrqview(real(tfr),x,t,'tfrmh');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;