function h=tftb_window(N,name,param,param2);%tftb_window	Window generation.%	H=tftb_window(N,NAME,PARAM,PARAM2)%	yields a window of length N with a given shape.%%	N      : length of the window%	NAME   : name of the window shape (default : Hamming)%	PARAM  : optional parameter%	PARAM2 : second optional parameters%%	Possible names are :%	'Hamming', 'Hanning', 'Nuttall',  'Papoulis', 'Harris',%	'Rect',    'Triang',  'Bartlett', 'BartHann', 'Blackman'%	'Gauss',   'Parzen',  'Kaiser',   'Dolph',    'Hanna'.%	'Nutbess', 'spline',  'Flattop'%%	For the gaussian window, an optionnal parameter K%	sets the value at both extremities. The default value is 0.005%%	For the Kaiser-Bessel window, an optionnal parameter%	sets the scale. The default value is 3*pi.%%	For the Spline windows, h=tftb_window(N,'spline',nfreq,p)%	yields a spline weighting function of order p and frequency%	bandwidth proportional to nfreq.%%       Example: %        h=tftb_window(256,'Gauss',0.005); %        plot(0:255, h); axis([0,255,-0.1,1.1]); grid%%	See also DWINDOW.%	F. Auger, June 1994 - November 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%%	References : %	- F.J. Harris, "On the use of windows for harmonic%	analysis with the discrete Fourier transform",%	Proceedings of the IEEE, Vol 66, No 1, pp 51-83, 1978.%	- A.H. Nuttal, "A two-parameter class of Bessel weighting %	functions for spectral analysis or array processing", %	IEEE Trans on ASSP, Vol 31, pp 1309-1311, Oct 1983.%	- Y. Ho Ha, J.A. Pearce, "A New window and comparison to%	standard windows", Trans IEEE ASSP, Vol 37, No 2, %	pp 298-300, February 1989.%	- C.S. Burrus, Multiband Least Squares FIR Filter Design,%	Trans IEEE SP, Vol 43, No 2, pp 412-421, February 1995.if (nargin==0), error ( 'at least 1 parameter is required' ); end;if (N<=0), error('N should be strictly positive.'); end;if (nargin==1), name= 'Hamming'; end ;name=upper(name);if strcmp(name,'RECTANG') | strcmp(name,'RECT'),  h=ones(N,1);elseif strcmp(name,'HAMMING'), h=0.54 - 0.46*cos(2.0*pi*(1:N)'/(N+1));elseif strcmp(name,'HANNING') | strcmp(name,'HANN'), h=0.50 - 0.50*cos(2.0*pi*(1:N)'/(N+1));elseif strcmp(name,'KAISER'), if (nargin==3), beta=param; else beta=3.0*pi; end; ind=(-(N-1)/2:(N-1)/2)' *2/N; beta=3.0*pi; h=besselj(0,j*beta*sqrt(1.0-ind.^2))/real(besselj(0,j*beta));elseif strcmp(name,'NUTTALL'), ind=(-(N-1)/2:(N-1)/2)' *2.0*pi/N; h=+0.3635819 ...   +0.4891775*cos(    ind) ...   +0.1363995*cos(2.0*ind) ...   +0.0106411*cos(3.0*ind) ;elseif strcmp(name,'BLACKMAN'), ind=(-(N-1)/2:(N-1)/2)' *2.0*pi/N; h= +0.42 + 0.50*cos(ind) + 0.08*cos(2.0*ind) ;elseif strcmp(name,'HARRIS'), ind=(1:N)' *2.0*pi/(N+1); h=+0.35875 ...   -0.48829 *cos(    ind) ...   +0.14128 *cos(2.0*ind) ...   -0.01168 *cos(3.0*ind);elseif strcmp(name,'BARTLETT') | strcmp(name,'TRIANG'), h=2.0*min((1:N),(N:-1:1))'/(N+1);elseif strcmp(name,'BARTHANN'), h=  0.38 * (1.0-cos(2.0*pi*(1:N)/(N+1))') ...   + 0.48 * min((1:N),(N:-1:1))'/(N+1);elseif strcmp(name,'PAPOULIS'), ind=(1:N)'*pi/(N+1); h=sin(ind);elseif strcmp(name,'GAUSS'), if (nargin==3), K=param; else K=0.005; end; h= exp(log(K) * linspace(-1,1,N)'.^2 );elseif strcmp(name,'PARZEN'), ind=abs(-(N-1)/2:(N-1)/2)'*2/N; temp=2*(1.0-ind).^3; h= min(temp-(1-2.0*ind).^3,temp);elseif strcmp(name,'HANNA'), if (nargin==3), L=param; else L=1; end; ind=(0:N-1)';h=sin((2*ind+1)*pi/(2*N)).^(2*L);elseif strcmp(name,'DOLPH') | strcmp(name,'DOLF'), if (rem(N,2)==0), oddN=1; N=2*N+1; else oddN=0; end; if (nargin==3), A=10^(param/20); else A=1e-3; end; K=N-1; Z0=cosh(acosh(1.0/A)/K); x0=acos(1/Z0)/pi; x=(0:K)/N;  indices1=find((x<x0)|(x>1-x0)); indices2=find((x>=x0)&(x<=1-x0)); h(indices1)= cosh(K*acosh(Z0*cos(pi*x(indices1)))); h(indices2)= cos(K*acos(Z0*cos(pi*x(indices2)))); h=fftshift(real(ifft(A*real(h))));h=h'/h(K/2+1); if oddN, h=h(2:2:K); end;elseif strcmp(name,'NUTBESS'), if (nargin==3), beta=param; nu=0.5;  elseif (nargin==4), beta=param; nu=param2; else beta=3*pi; nu=0.5; end; ind=(-(N-1)/2:(N-1)/2)' *2/N;  h=sqrt(1-ind.^2).^nu .* ...   real(besselj(nu,j*beta*sqrt(1.0-ind.^2)))/real(besselj(nu,j*beta));elseif strcmp(name,'SPLINE'), if (nargin < 3),  error('Three or four parameters required for spline windows'); elseif (nargin==3),  nfreq=param; p=pi*N*nfreq/10.0; else nfreq=param; p=param2; end;  ind=(-(N-1)/2:(N-1)/2)';   h=sinc((0.5*nfreq/p)*ind) .^ p;elseif strcmp(name,'FLATTOP'), ind=(-(N-1)/2:(N-1)/2)' *2.0*pi/(N-1); h=+0.2810639 ...   +0.5208972*cos(    ind) ...   +0.1980399*cos(2.0*ind) ;else error('unknown window name');end;