see the small singular values as in <a href="http://www.netlib.org/lapack/lawnspdf/lawn03.pdf">http://www.netlib.org/lapack/lawnspdf/lawn03.pdf</a>:</p><p>Generate a matrix A:</p><pre class="codeinput">eta = eps(1)/2;
x = eta; <span class="comment">% the smallest sigma ~ eta^3</span>
<span class="comment">%x = 0; % the smallest sigma ~ eta^2/sqrt(2) % good test for deflation</span>
A = [eta^2 1 0 0; 0 1 x 0; 0 0 1 1; 0 0 0 eta^2];
</pre><p>Change format:</p><pre class="codeinput">format <span class="string"