test_rld.m

% benchmark code for RLD solutions posted at http://stackoverflow.com/q/1975772/2778484
% Results posted in CW: http://stackoverflow.com/a/29084077/2778484

%% bench
datasizes = [reshape(linspace(10,70,4).'*10.^(0:4),1,[]) 10^6 2*10^6]; %//'
fcns = {'repelem','rld_cumsum','rld_cumsum_diff'}; %// approaches to be benchmarked
tsec = zeros(numel(fcns),numel(datasizes));

for k1 = 1:numel(datasizes),
    n = datasizes(k1); %// Create random inputs
    fprintf('Data size: %d\n',n);
    vals = randi(200,1,n);
    runs = [5000 randi(200,1,n-1)]; %// 5000 acts as an aberration
    for k2 = 1:numel(fcns), %// Time approaches  
        tsec(k2,k1) = timeit(@() feval(fcns{k2}, vals,runs), 1);
        fprintf('\tFunction: %s (%3.2f sec)\n',fcns{k2},tsec(k2,k1));
    end
end

%% plot
figure,      %// Plot runtimes
loglog(datasizes,tsec(1,:),'-rx'), hold on
loglog(datasizes,tsec(2,:),'-bo')
loglog(datasizes,tsec(3,:),'-k+')
set(gca,'xgrid','on'),set(gca,'ygrid','on'),
xlabel('Datasize (# elements)'), ylabel('Runtime (s)')
legend(upper(strrep(fcns,'_',' '))),title('Runtime')

%% rate plot
elementsPerSec = bsxfun(@rdivide,datasizes,tsec);
figure;
semilogx(datasizes,elementsPerSec(1,:),'-rx'), hold on
semilogx(datasizes,elementsPerSec(2,:),'-bo')
semilogx(datasizes,elementsPerSec(3,:),'-k+')
set(gca,'xgrid','on'),set(gca,'ygrid','on'),
xlabel('Datasize (# elements)'), ylabel('Processing rate (elements/sec)')
legend(upper(strrep(fcns,'_',' '))),title('Rate')

%% plot speedup
figure,      %// Plot speedups
semilogx(datasizes,tsec(1,:)./tsec(2,:),'-rx')        
set(gca,'ygrid','on'), xlabel('Datasize ->')
legend('Speedup(x) with cumsum+diff over cumsum-only'),title('Speedup Plot')