X-Git-Url: https://git.creatis.insa-lyon.fr/pubgit/?p=CreaPhase.git;a=blobdiff_plain;f=octave_packages%2Fm%2Fsignal%2Fhurst.m;fp=octave_packages%2Fm%2Fsignal%2Fhurst.m;h=3d51821eaf6b62382fdc4388c57a5439ecc58cc9;hp=0000000000000000000000000000000000000000;hb=1c0469ada9531828709108a4882a751d2816994a;hpb=63de9f36673d49121015e3695f2c336ea92bc278
diff --git a/octave_packages/m/signal/hurst.m b/octave_packages/m/signal/hurst.m
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+## Copyright (C) 1995-2012 Friedrich Leisch
+##
+## This file is part of Octave.
+##
+## Octave 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.
+##
+## Octave 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 Octave; see the file COPYING. If not, see
+## .
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {} hurst (@var{x})
+## Estimate the Hurst parameter of sample @var{x} via the rescaled range
+## statistic. If @var{x} is a matrix, the parameter is estimated for
+## every single column.
+## @end deftypefn
+
+## Author: FL
+## Description: Estimate the Hurst parameter
+
+function H = hurst (x)
+
+ if (nargin != 1)
+ print_usage ();
+ endif
+
+ if (isscalar (x))
+ error ("hurst: X must not be a scalar");
+ elseif (isvector (x))
+ x = reshape (x, length (x), 1);
+ endif
+
+ [xr, xc] = size (x);
+
+ s = std (x);
+ w = cumsum (x - mean (x));
+ RS = (max(w) - min(w)) ./ s;
+ H = log (RS) / log (xr);
+
+endfunction