 have to be within those of the original operator. In fact, we can specify indices that don't overlap at all with the original operator, and we will simply end up with a larger operator. Zero out part of A:</p><pre class="codeinput">A(1:2,:) = 0;
double(A)
</pre><pre class="codeoutput">
ans =

     0     0     0     0     0
     0     0     0     0     0
     0     0     3     0     0
     0     0     0     4     0
     0     0     0     0     5

</pre><p>Assign a new operator, C, to a subset of B:</p><pre 