12px;">x = </span></div><div style="white-space: pre; font-style: normal; color: rgb(64, 64, 64); font-size: 12px;">  -3.0000e+00
   1.0000e+00
   4.0000e+00
  -2.0000e+00
</div></div></div></div></div></div></div></div>
<!-- 
##### SOURCE BEGIN #####
%% 
% Here is the system that ``broke" LU factorization for us.

A = [ 2 0 4 3; -2 0 2 -13 ; 1 15 2 -4.5 ; -4 5 -7 -10 ];
b = [ 4; 40; 29; 9 ];
%% 
% When we use the built-in |lu| function with three outputs, we get the 
% elements of the PLU factorization.
%%