e class="codeinput">A = rand (200,1000) ;
b = rand (200,1) ;

tic ; x = A\b            ; toc, norm (x)
tic ; x = pinv(A)*b      ; toc, norm (x)
tic ; x = inverse(A)*b   ; toc, norm (x)
tic ; x = factorize(A)\b ; toc, norm (x)
</pre><pre class="codeoutput">Elapsed time is 0.078900 seconds.
ans =
    3.2259
Elapsed time is 0.356762 seconds.
ans =
    0.4610
Elapsed time is 0.082058 seconds.
ans =
    0.4610
Elapsed time is 0.082241 seconds.
ans =
    0.4610
</pre><h2>Computing selected entries in the inverse 