function [y,iflaw]=fmlin(N,fnormi,fnormf,t0);%FMLIN	Signal with linear frequency modulation.%	[Y,IFLAW]=FMLIN(N,FNORMI,FNORMF,T0) generates a linear frequency  %	modulation.%	The phase of this modulation is such that Y(T0)=1.%%	N       : number of points%	FNORMI  : initial normalized frequency (default: 0.0)%	FNORMF  : final   normalized frequency (default: 0.5)%	T0      : time reference for the phase (default: N/2).%	Y       : signal%	IFLAW   : instantaneous frequency law  (optional).%%	Example : %	 z=amgauss(128,50,40).*fmlin(128,0.05,0.3,50); %	 plot(real(z));%%	see also FMCONST, FMSIN, FMODANY, FMHYP, FMPAR, FMPOWER.%	F. Auger, 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 if (nargin == 0), error ( 'The number of parameters must be at least 1.' );elseif (nargin == 1), fnormi=0.0; fnormf=0.5; t0= N/2;elseif (nargin == 2), fnormf=0.5; t0 = N/2;elseif (nargin == 3), t0 = N/2;end;if (N <= 0), error ('The signal length N must be strictly positive' );elseif (abs(fnormi) > 0.5) | (abs(fnormf) > 0.5), error ( 'fnormi and fnormf must be between -0.5 and 0.5' ) ;else y = (1:N)'; y = fnormi*(y-t0) + ((fnormf-fnormi)/(2.0*(N-1))) * ((y-1).^2 - (t0-1).^2); y = exp(j*2.0*pi*y) ; y=y/y(t0); if (nargout==2), iflaw=linspace(fnormi,fnormf,N).'; end;end ;