Check lazy copy behavior of struct in MATLAB

MATLAB_struct_innerval_looptest.m

%   ref: https://kr.mathworks.com/matlabcentral/answers/719-declaring-many-variables-from-work-space-into-function-workspace
%% Init
close all; clear; clc; disp(mfilename);
N=5;

%% Main
S = struct;
S.increment = 1;
S.x = 0;
S = allocatelargevariable(S);

%% increase var inside S without re-assigning
for k = 1:N
    disp(k);
    S = increasevar(S);
end
%% increase var inside S with label change
for k = 1:N
    disp(k);
    S = increasevarwithlabelchange(S);
end
%% increase var inside S with re-assigning
for k = 1:N
    disp(k);
    S = increasevarwithreassign(S);
end
%% increase var inside S with explicit assigning
for k = 1:N
    disp(k);
    S = increasevarwithexplicitassign(S);
end

%% function definitions
function [S] = allocatelargevariable(S)
%allocateLargevariable Allocate large variable in struct S
S.largevariable = rand(20000);
end

function [S] = increasevar(S)
S.x = S.x + S.increment;
end

function [output] = increasevarwithlabelchange(S)
S.x = S.x + S.increment;
output=S;
end

function [S2] = increasevarwithreassign(S)
S2 = S;
S2.x = S.x + S.increment;
end

function [S2] = increasevarwithexplicitassign(S)
S2 = S;
S2 = allocatelargevariable(S2);
S2.x = S.x + S.increment;
end