Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / tsa-4.2.4 / flix.m

diff --git a/octave_packages/tsa-4.2.4/flix.m b/octave_packages/tsa-4.2.4/flix.m
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+function Y=flix(D,x)
+% floating point index - interpolates data in case of non-integer indices
+%
+% Y=flix(D,x)
+%   FLIX returns Y=D(x) if x is an integer 
+%   otherwise D(x) is interpolated from the neighbors D(ceil(x)) and D(floor(x)) 
+% 
+% Applications: 
+% (1)  discrete Dataseries can be upsampled to higher sampling rate   
+% (2)  transformation of non-equidistant samples to equidistant samples
+% (3)  [Q]=flix(sort(D),q*(length(D)+1)) calculates the q-quantile of data series D   
+%
+% FLIX(D,x) is the same as INTERP1(D,X,'linear'); Therefore, FLIX might
+% become obsolete in future. 
+%
+% see also: HIST2RES, Y2RES, PLOTCDF, INTERP1
+
+%      $Id: flix.m 5090 2008-06-05 08:12:04Z schloegl $
+%      Copyright (C) by 2001-2005,2008 Alois Schloegl <a.schloegl@ieee.org>    
+%      This is part of the TSA-toolbox see also: 
+%         http://www.dpmi.tu-graz.ac.at/schloegl/matlab/tsa/
+%         http://octave.sf.net/
+%
+%    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/>.
+
+D  = D(:);
+Y  = x;
+
+k1 = ((x >= 1) & (x <= size(D,1)));    
+Y(~k1) = NaN;
+
+k  = x - floor(x);     % distance to next sample        
+
+ix = ~k & k1;          % find integer indices
+Y(ix) = D(x(ix));      % put integer indices
+
+ix = k & k1;           % find non-integer indices
+
+Y(ix) = D(floor(x(ix))).*(1-k(ix)) + D(ceil(x(ix))).*k(ix);  
+