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: SY_StatAv.m
    path of file: ./repos/hctsa/Operations
    
    the code of the file until where you have to start completion: function out = SY_StatAv(y,whatType,n)
% SY_StatAv     Simple mean-stationarity metric, StatAv.
%
% The StatAv measure divides the time series into non-overlapping subsegments,
% calculates the mean in each of these segments and returns the standard deviation
% of this set of means.
%
% Empirically mean-stationary data would display StatAv approaching to zero.
%
% cf. "Heart rate control in normal and aborted-SIDS infants", S. M. Pincus et al.
% Am J. Physiol. Regul. Integr. Comp. Physiol. 264(3) R638 (1993)
%
%---INPUTS:
%
% y, the input time series
%
% whatType, the type of StatAv to perform:
%           (i) 'seg': divide the time series into n segments
%           (ii) 'len': divide the time series into segments of length n
%

    
function out = SY_StatAv(y,whatType,n)
% SY_StatAv     Simple mean-stationarity metric, StatAv.
%
% The StatAv measure divides the time series into non-overlapping subsegments,
% calculates the mean in each of these segments and returns the standard deviation
% of this set of means.
%
% Empirically mean-stationary data would display StatAv approaching to zero.
%
% cf. "Heart rate control in normal and aborted-SIDS infants", S. M. Pincus et al.
% Am J. Physiol. Regul. Integr. Comp. Physiol. 264(3) R638 (1993)
%
%---INPUTS:
%
% y, the input time series
%
% whatType, the type of StatAv to perform:
%           (i) 'seg': divide the time series into n segments
%           (ii) 'len': divide the time series into segments of length n
%
% n, either the number of subsegments ('seg') or their length ('len')

% Might be nicer to use the 'buffer' function for this...?
% ------------------------------------------------------------------------------
% Copyright (C) 2020, 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/>.
% ------------------------------------------------------------------------------

% ------------------------------------------------------------------------------
% Check Inputs
% ------------------------------------------------------------------------------
if nargin < 2 || isempty(whatType)
    whatType = 'seg'; % divide into n segments by default
end