X-Git-Url: https://git.creatis.insa-lyon.fr/pubgit/?p=CreaPhase.git;a=blobdiff_plain;f=octave_packages%2Ftsa-4.2.4%2Fbispec.m;fp=octave_packages%2Ftsa-4.2.4%2Fbispec.m;h=d50804cad2cff63866c3eeccb33c92087396672c;hp=0000000000000000000000000000000000000000;hb=f5f7a74bd8a4900f0b797da6783be80e11a68d86;hpb=1705066eceaaea976f010f669ce8e972f3734b05

diff --git a/octave_packages/tsa-4.2.4/bispec.m b/octave_packages/tsa-4.2.4/bispec.m
new file mode 100644
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+++ b/octave_packages/tsa-4.2.4/bispec.m
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+function [BISPEC,BIACF,ACF] = bispec(Z,N);
+% Calculates Bispectrum 
+% [BISPEC] = bispec(Z,N);
+%
+% Input:	Z    Signal
+%		N  # of coefficients
+% Output:	BiACF  bi-autocorrelation function = 3rd order cumulant
+%		BISPEC Bi-spectrum 
+%
+% Reference(s):
+% C.L. Nikias and A.P. Petropulu "Higher-Order Spectra Analysis" Prentice Hall, 1993.
+% M.B. Priestley, "Non-linear and Non-stationary Time series Analysis", Academic Press, London, 1988.
+
+%	$Id: bispec.m 5090 2008-06-05 08:12:04Z schloegl $
+%	Copyright (C) 1997-2003,2008 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/>.
+
+
+P=N+1;
+ACF=zeros(1,N+1);
+BIACF=zeros(2*N+1,2*N+1);
+
+Z=Z(:);
+M=size(Z,1);
+M1=sum(Z)/M;
+Z=Z-M1*ones(size(Z));
+
+for K=0:N, 
+	jc2=Z(1:M-K).*Z(1+K:M);
+	ACF(K+1)=sum(jc2)/M;
+	for L = K:N,
+		jc3 = sum(jc2(1:M-L).*Z(1+L:M))/M;
+		BIACF(K+P,  L+P)  =jc3;
+		BIACF(L+P,  K+P)  =jc3;
+		BIACF(L-K+P, -K+P)=jc3;
+		BIACF(-K+P, L-K+P)=jc3;
+		BIACF(K-L+P, -L+P)=jc3;
+		BIACF(-L+P, K-L+P)=jc3;
+	end;
+end;
+
+BISPEC=fft2(BIACF,128,128);