amgauss.m

function y = amgauss(N,t0,T);
%AMGAUSS Generate gaussian amplitude modulation.
%	Y=AMGAUSS(N,T0,T) generates a gaussian amplitude modulation 
%	centered on a time T0, and with a spread proportional to T.
%	This modulation is scaled such that Y(T0)=1 
%	and Y(T0+T/2) and Y(T0-T/2) are approximately equal to 0.5 .
% 
%	N  : number of points.
%	T0 : time center		(default : N/2).
%	T  : time spreading		(default : 2*sqrt(N)). 
%	Y  : signal.
%
%	Examples:
%	 z=amgauss(160); plot(z);
%	 z=amgauss(160,90,40); plot(z);
%	 z=amgauss(160,180,50); plot(z);
%
%	See also AMEXPO1S, AMEXPO2S, AMRECT, AMTRIANG.

%	F. Auger, July 1995.
%	Copyright (c) 1996 by CNRS (France).
%
%  This program is free software; you can redistribute it and/or modify
%  it under the terms of the GNU General Public License as published by
%  the Free Software Foundation; either version 2 of the License, or
%  (at your option) any later version.
%
%  This program is distributed in the hope that it will be useful,
%  but WITHOUT ANY WARRANTY; without even the implied warranty of
%  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
%  GNU General Public License for more details.
%
%  You should have received a copy of the GNU General Public License
%  along with this program; if not, write to the Free Software
%  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

if (nargin == 0),
 error ( 'The number of parameters must be at least 1.' );
elseif (nargin == 1),
 t0=N/2; T=2*sqrt(N);
elseif (nargin ==2),
 T=2*sqrt(N);
end;

if (N<=0),
 error('N must be greater or equal to 1.');
else
 tmt0=(1:N)'-t0;
 y = exp(-(tmt0/T).^2 * pi);
end;