function dzt=zak(sig,N,M)%ZAK 	Zak transform.%	DZT=ZAK(SIG,N,M) computes the Zak transform of signal SIG.%%	SIG : Signal to be analysed (length(X)=N1).%	N   : number of Zak coefficients in time (N1 must be a multiple%	      of N)          (default : closest integer towards sqrt(N1)). %	M   : number of Zak coefficients in frequency (N1 must be a%	      multiple of M) (default : M=N1/N).%	DZT : Output matrix (N,M) containing the discrete Zak transform.%%	Example : %	 sig=fmlin(256); DZT=zak(sig);%	 imagesc(DZT);%%	See also IZAK, TFRGABOR.%	O. Lemoine - February 1996.%	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 N1=length(sig);if N1<=2,  error('SIG must have at least 3 elements');elseif nargin<1,  error('The number of parameters must be at least one');elseif nargin==1,  [N,M]=divider(N1);elseif nargin==2,  N=N1/M;elseif M<=1|N<=1|M>=N1|N>=N1,  error('M and N must be between 2 and N1-1');elseif rem(N1,M)~=0|rem(N1,N)~=0,  error('M and N must be such that N1 is a multiple of M and N');endMsig=zeros(M,N);dzt=zeros(N,M);Msig=reshape(sig,M,N);dzt=fft(Msig.')/sqrt(N);