本代码可用来提取计算心率变异性非线性域特征值（SampEnVal, AlphaDFA, AlphaDFA1, AlphaDFA2 ）(Extract Nonlinear features of HRV.

%Inputs:　　RRI = inter-beat interval (s) and time locations (s)
%　　　　　 opt = analysis options from gui
%　　　　　
%Outputs:　 output is a structure containg all HRV.
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% Copyright (C) 2010, John T. Ramshur, jramshur@gmail.com
%
% This file is part of HRVAS
%
% HRVAS 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.
%
% HRVAS 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.)