You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: MD_rawHRVmeas.m
    path of file: ./repos/hctsa/Operations
    
    the code of the file until where you have to start completion: function out = MD_rawHRVmeas(x)
% MD_rawHRVmeas     Poincare plot measures used in HRV analysis.
%                   HRV: heart rate variability.
%
% Computes the triangular histogram index and Poincare plot measures to a time
% series assumed to measure sequences of consecutive RR intervals measured in
% milliseconds. Doesn't make much sense for other time series
%
% cf. "Do existing measures of Poincare plot geometry reflect nonlinear
%      features of heart rate variability?"
%      M. Brennan, et al., IEEE T. Bio.-Med. Eng. 48(11) 1342 (2001)
%
% Note that pNNx is not done here, but in MD_pNN.m
%
% This code is heavily derived from Max Little's hrv_classic.m code
% Max Little: http://www.maxlittle.net/

% ------------------------------------------------------------------------------
% Copyright (C) 2016, Max A. Little, <max.a.little@gmail.com>,
% <http://www.maxlittle.net/> and Ben D. Fulcher <ben.d.fulcher@gmail.com>,
% <http://www.benfulcher.com>
%
% If you use this code for your research, please cite the following two papers:
%
% (1) B.D. Fulcher and N.S. Jones, "hctsa: A Computational Framework for Automated
% Time-Series Phenotyping Using Massive Feature Extraction, Cell Systems 5: 527 (2017).
% DOI: 10.1016/j.cels.2017.10.001
%
% (2) B.D. Fulcher, M.A. Little, N.S. Jones, "Highly comparative time-series
% analysis: the empirical structure of time series and their methods",
% J. Roy. Soc. Interface 10(83) 20130048 (2013).
% DOI: 10.1098/rsif.2013.0048
%
% This function 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.

    
function out = MD_rawHRVmeas(x)
% MD_rawHRVmeas     Poincare plot measures used in HRV analysis.
%                   HRV: heart rate variability.
%
% Computes the triangular histogram index and Poincare plot measures to a time
% series assumed to measure sequences of consecutive RR intervals measured in
% milliseconds. Doesn't make much sense for other time series
%
% cf. "Do existing measures of Poincare plot geometry reflect nonlinear
%      features of heart rate variability?"
%      M. Brennan, et al., IEEE T. Bio.-Med. Eng. 48(11) 1342 (2001)
%
% Note that pNNx is not done here, but in MD_pNN.m
%
% This code is heavily derived from Max Little's hrv_classic.m code
% Max Little: http://www.maxlittle.net/

% ------------------------------------------------------------------------------
% Copyright (C) 2016, Max A. Little, <max.a.little@gmail.com>,
% <http://www.maxlittle.net/> and Ben D. Fulcher <ben.d.fulcher@gmail.com>,
% <http://www.benfulcher.com>
%
% If you use this code for your research, please cite the following two papers:
%
% (1) B.D. Fulcher and N.S. Jones, "hctsa: A Computational Framework for Automated
% Time-Series Phenotyping Using Massive Feature Extraction, Cell Systems 5: 527 (2017).
% DOI: 10.1016/j.cels.2017.10.001
%
% (2) B.D. Fulcher, M.A. Little, N.S. Jones, "Highly comparative time-series
% analysis: the empirical structure of time series and their methods",
% J. Roy. Soc. Interface 10(83) 20130048 (2013).
% DOI: 10.1098/rsif.2013.0048
%
% This function 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/>.
% ------------------------------------------------------------------------------

N = length(x); % time-series length

% Triangular histogram index
out.tri10 = N/max(histcounts(x,10));
out.tri20 = N/max(histcounts(x,20));
out.trisqrt = N/max(histcounts(x,'BinMethod','sqrt'));

% 'Poincare plot measures': see
% "Do Existing Measures ... ", Brennan et. al. (2001), IEEE Trans Biomed Eng 48(11)
diffx = diff(x);
out.SD1 = 1/sqrt(2) * std(diffx) * 1000;
out.SD2 = sqrt(2 * var(x) - (1/2) * std(diffx)^2) * 1000;

% NOTE: the SD1 measure is the same (up to a linear transformation)
%       as the implementation in DN_Spread(diff(x),'std');

end