function compare_qsvd(A, epsilon)
    if(nargin < 2) 
        epsilon = 0.01;
    end

    % fast matrix warmup for fair comparison - 
    % this way neither method has to wait for A to get into cpu cache
    [u,s,v] = qsvd(A,.9);
    
    tic;
    [u,s,v] = qsvd(A, epsilon);
    qsvdTime = toc;
    fprintf('\tqsvd: %.4f sec\n', qsvdTime);

    [m,n] = size(A);
    if(m > 1500 && n > 1500), fprintf('(patience...matlab svd may take a few minutes)\n'); end
    tic;
    [u,s,v] = svd(A,'econ');
    exactTime = toc;
    fprintf('\tmatlab: %.4f sec\n', exactTime);

    fprintf('\tqsvd speedup: %.4f\n',exactTime/qsvdTime);
end