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diff --git a/octave_packages/tsa-4.2.4/pacf.m b/octave_packages/tsa-4.2.4/pacf.m
new file mode 100644
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+function [PARCOR,sig,cil,ciu]= pacf(Z,KMAX);
+% Partial Autocorrelation function
+% [parcor,sig,cil,ciu] = pacf(Z,N);
+%
+% Input:
+%	Z    Signal, each row is analysed
+%	N    # of coefficients
+
+% Output:	
+%	parcor autocorrelation function
+%	sig	p-value for significance test
+%	cil	lower confidence interval 
+%	ciu	upper confidence interval 
+% 
+% see also: DURLEV, LATTICE, AC2RC, AR2RC,
+% 	FLAG_IMPLICIT_SIGNIFICANCE
+
+%	$Id: pacf.m 5090 2008-06-05 08:12:04Z schloegl $
+%	Copyright (C) 1997-2002,2008 by Alois Schloegl <a.schloegl@ieee.org>	
+%
+%    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 3 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, see <http://www.gnu.org/licenses/>.
+
+[nr,nc] = size(Z);
+if nc<KMAX,
+        warning('too less elements.\nmake sure the data is row order\n')
+end;
+[s,n] = sumskipnan(Z,2);
+Z = Z - repmat(s./n,1,nc); 	% remove mean
+
+if (nargin == 1), KMAX = N-1; end;
+
+AutoCov = acovf(Z,KMAX);
+[AR,PARCOR,PE] = durlev(AutoCov); % PARCOR are the reflection coefficients
+%[AR,PARCOR,PE] = lattice(Z,KMAX); % PARCOR are the reflection coefficients
+PARCOR = -PARCOR;			% the partial correlation coefficients are the negative reflection coefficient.
+
+if nargout<2, return, end;
+
+
+% significance test
+s = 1./sqrt(repmat(n,1,KMAX)-1-ones(nr,1)*(1:KMAX));
+sig = normcdf(PARCOR,0,s);
+sig = min(sig,1-sig);
+
+
+if nargout<3, return, end;
+% calculate confidence interval
+if exist('flag_implicit_significance')==2;
+        alpha = flag_implicit_significance;
+else	
+        alpha = 0.05;
+end;        
+
+fprintf(1,'PACF: confidence interval for alpha=%f\n', alpha);
+ciu = norminv(alpha/2).*s;
+cil = -ciu;        
+
+