www.gusucode.com > 时间序列分析工具箱 - tsa源码程序 > tsa/flix.m
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 % 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA % $Id: flix.m,v 1.10 2005/05/25 13:02:03 schloegl Exp $ % Copyright (C) by 2001-2005 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/ 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);