shuffling(int8(1:20))

x = 1:200000;
numel(unique(shuffling(x)))

% REMARK: shuffling code is interpreted whereas randperm is compiled;
% therefore, the comparison has to be done using tic-toc statements, 
% as in the example below (the MATLAB profiler would over-estimate the 
% shuffling time). 
RefTime = 1;
for n = [10, 10^2, 10^3, 10^4, 10^5, 10^6, 10^7]
X = 1:n;
% Estimate the number of profiling loops:
iniTime = cputime;
countLoop = 0;
while cputime - iniTime < RefTime
Xp = X(randperm(n));  
clear('Xp');   % Necessary to suppress JIT acceleration
countLoop = countLoop + 1;
end
nDigit = max(1, floor(log10(max(1, countLoop))) - 1);
nLoop  = max(4, round(countLoop / 10 ^ nDigit) * 10 ^ nDigit);
% monitor randperm
tic;
for i = 1:nLoop
Xp = X(randperm(n));
clear('Xp');
end
RandPermTime = toc;
% monitor shuffling
tic;
for i = 1:nLoop
Xp = shuffling(X);
clear('Xp');
end
ShufflingTime = toc;
% results
fprintf('\n%d elements shuffled %d times: \n', n, nLoop);
disp(['    - shuffling etime (seconds): ' num2str(ShufflingTime)]);
disp(['    - randperm  etime (seconds): ' num2str(RandPermTime)]);
fprintf('SHUFFLING TIME IS %.1f%% of RANDPERM TIME\n', 100.0 * ShufflingTime / RandPermTime);
end

% Note that results can differ between MATLAB releases. See below.
stoc = 0; rtoc = 0; loops = 100; n = zeros(100,1);
for i=1:loops
n(i) = randi(1000000 , 1);
%n(i) = floor(1000000*abs(randn));
x = randi(1000000 , n(i) , 1);
nn=numel(x);
st = tic;
xperm1 = shuffling(x);
stoc = stoc+toc(st);
rt = tic;
ix = randperm(nn);
xperm2 = x(ix);
rtoc = rtoc+toc(rt);
clear('xperm1','ix','xperm2'); % Necessary to suppress JIT acceleration, for realistic times
end
disp(['shuffling etime (seconds): ' num2str(stoc)]);
disp(['randperm  etime (seconds): ' num2str(rtoc)]);
fprintf('==> SHUFFLING TIME IS %.1f%% of RANDPERM TIME\n', 100.0 * stoc / rtoc);
% Results on R2016b
%     shuffling etime (seconds): 4.5303
%     randperm  etime (seconds): 5.3804
%     ==> SHUFFLING TIME IS 84.2% of RANDPERM TIME
% Results on R2012a
% shuffling etime (seconds): 7.9629
% randperm  etime (seconds): 4.9526
% ==> SHUFFLING TIME IS 160.8% of RANDPERM TIME
% Results on R2009a
% shuffling etime (seconds): 8.4239
% randperm  etime (seconds): 9.5947
% ==> SHUFFLING TIME IS 87.8% of RANDPERM TIME