ute inv(A) and
            use it twice.  Easy to write, but slower and less accurate ...
         </p><pre class="codeinput">S = inv (A) ;
x = S*b ; norm (b-A*x)
y = S*c ; norm (c-A*y)
</pre><pre class="codeoutput">ans =
   3.5716e-11
ans =
   7.7556e-12
</pre><p>Sometimes using the inverse seems inevitable.  For example, your textbook might show the Schur complement formula as S = A-B*inv(D)*C.
             This can be done without inv(D) in one of two ways: SLASH or BACKSLASH (MRDIVIDE or MLDIVIDE to be 