Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / nan-2.5.5 / nanfilter.m

diff --git a/octave_packages/nan-2.5.5/nanfilter.m b/octave_packages/nan-2.5.5/nanfilter.m
new file mode 100644 (file)
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+++ b/octave_packages/nan-2.5.5/nanfilter.m
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+function [Y,Z] = nanfilter(B,A,X,z);
+% NANFILTER is able to filter data with missing values encoded as NaN. 
+%       
+%      [Y,Z] = nanfilter(B,A,X [, Z]);  
+%
+% If X contains no missing data, NANFILTER should behave like FILTER. 
+% NaN-values are handled gracefully. 
+%
+% WARNING: missing values can introduce aliasing - causing unintended results.
+%    Moreover, the behavior of bandpass and highpass filters in case of missing values 
+%    is not fully understood, and might contain some pitfalls.  
+%
+% see also: FILTER, SUMSKIPNAN, NANFFT, NANCONV, NANFILTER1UC
+
+%      $Id$
+%      Copyright (C) 2005,2011 by Alois Schloegl <alois.schloegl@gmail.com>            
+%       This function is part of the NaN-toolbox available at 
+%       http://pub.ist.ac.at/~schloegl/matlab/NaN/ and 
+%      http://octave.svn.sourceforge.net/viewvc/octave/trunk/octave-forge/extra/NaN/inst/
+
+%    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, write to the Free Software
+%    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA
+
+
+warning('NANFILTER is experimental. For more details see HELP NANFILTER');
+
+na = length(A);
+nb = length(B);
+if any(size(X)==1)
+       nc = 1; 
+else   
+       nc = size(X,2);
+end; 
+
+if nargin<4,
+        [t,Z.S] = filter(B,A,zeros(na+nb,nc));
+        [t,Z.N] = filter(B,A,zeros(na+nb,nc));
+elseif isnumeric(z),
+        Z.S = z; 
+        [t, Z.N] = filter(B, A, zeros(na+nb,nc));
+elseif isstruct(z),
+        Z = z; 
+end;
+
+NX        = isnan(X);
+X(NX)     = 0;
+
+[Y , Z.S] = filter(B, A,   X, Z.S);
+[NY, Z.N] = filter(B, A, ~NX, Z.N);
+Y = (sum(B)/sum(A)) * Y./NY;
+